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kingcreaky
03-10-2012, 11:13 PM
evening all.
first off, thanks to all that have posted on this forum. It really comes across as a friendly inviting community of like minded individuals.
As I mentioned yesterday in my 'hello' post. The time has come for me to commence (or at least thinking a bit more seriously about) my CNC machine. Well, in actual fact CNC router I guess.

Ive sold an my pride and joy '68 mini van' which has freed up my workshop area. The nights are drawing in, the caravan is packed away and its now workshop season.

The intention is, to manufacture a flat bed miller. In order to fundamentally cut / carve wood. However, while I am there I wish to make it well enough to cut aluminum which I think will be ultra handy for some other projects I have in mind.

Id like to make it about 3m by 3m however I dont think my bank balance will afford it. I dont want to compromise too much on size just because of the cost so if I can achieve a working area of around 1m x 1m I wont be too disappointed.
My original idea was to copy some of these angled ali / bearing linear ideas I see so frequently on youtube with a wooden frame etc. However after reading some of your thoughts and comments on here Ive decided to do it properly, so if at any point I seem to be cutting corners please feel free to point it out.
Today I have learnt alot. The differences for example between Trapezoidal Spindles and Ballscrews for example. Vibration, jitter etc

On request of fellow members of this forum, I think its prudent I make some drawings discuss all my ideas etc before I go balls deep and order the gear. So today has been a crash course in 'sketchup' which incidently ROCKS. Ive attached pictures of my gantry design

It is, to be fair a bit similar to motoxys. But as there was so much discussion around this subject I hope he doesnt mind me harnessing the wealth of ideas around this very subject.

So assuming the gantry is 1300mm does this look about ok?

(If there is anybody out there, not used sketchup before, or just want to copy this design, ive uploaded my sketchup file for the below for free download to anybody who is interested http://www.pensys.co.uk/cnc1.skp

kingcreaky
04-10-2012, 03:06 PM
spent most of last night laying awake. I get a bit like this when im 'on one' with something like this.

The more I read, the more ive established that the cutting ali is all about getting the strength in the right places. You dont want things flexing. I fear this may be copying another idea ive seen somewhere, but instead of having big lanky gantry support uprights with the linears at the bottom... how about having the linear rail at the top. this way, I dont have to decide now what the maximum height I want to work with is, plus I think its likely it will be very rare that im dealing with anything 'deep' as such. therefore I can cater for bigger objects by lowering the cutting deck and from an amount of movement I have available in my z axis?

I have an abundance of wood available to me, so Im thinking the uprights and cross members that support the Y linears etc (the table as it where) is going to be made of wood. then the gantry out of ali... does anybody think this is a really bad idea?

anyway, ive made some more pictures available...
7040704170427043

I think im going to have two ballscrews for the gantry (one at either side) with two steppers.

Jonathan
04-10-2012, 03:12 PM
The design you've just posted with the tool operating below the X-rails is far stronger, especially with an adjustable height bed. See mine here (http://www.mycncuk.com/forums/router-build-logs/2288-1-7%2A0-74%2A0-4m-mill-router-building.html#post24485) (or come and see it in real life if you want), don't pay much attention to the Y-axis though as that's weak.


I have an abundance of wood available to me, so Im thinking the uprights and cross members that support the Y linears etc (the table as it where) is going to be made of wood. then the gantry out of ali... does anybody think this is a really bad idea?

I do...it is far easier to make a machine to cut aluminium efficiently if you only use metals in the design. You'll need to use coolant if you're cutting aluminium regularly and clearly the wood wont last long or stay put if it's getting wet. You'll be much better off with making a steel frame. I get steel box section from a place called Adey Steel in Loughborough, which is not too far from you. 60mm box section is a good size for the frame and if you stick to 3mm wall thickness it's much easier to weld with a cheap welder.

Not sure what thickness it is in the drawing, but the Z-axis plate looks a bit thin. 20mm thick is a good size.

Put a few supports for the long rails on the frame to help stop them bending towards the middle.

(Edit, forget this bit - written before previous post.

With the one piece of box section the gantry torsional stiffness is quite poor - imagine what happens when you apply a force to the cutter when the Z-axis is at it's lowest point, the gantry will twist. If you just put a second piece of box section below the top one, aligned to the bottom face of the aluminium plate then the torsional stiffness will be much improved.

If you're after 1m travel then a 1300mm wide gantry is a bit generous since 200mm is plenty for a Z-axis.

Instead of putting the rails for the Z-axis on the Y-axis carriage, put them on the plate which holds the spindle and moves up/down and have the bearings attached to the Y-axis. This is generally a stronger configuration, especially with an adjustable height bed, since it minimises the vertical distance between the cutter and the support bearings (the overhang). This also can save some aluminium, depending on where you put the stepper motor.)

irving2008
04-10-2012, 04:12 PM
Another thought/idea: if you're going for that layout is to consider putting the x-axis motors/rotating ballnuts on the gantry rather than rotate the ballscrews. This way you could easily upgrade from 1m to 3m by changing out the ballscrews & x-rails and retain the same motors/etc. and you dont need to invest in expensive bearings for the ballscrews. The downside is marginally more weight on the gantry and constructing rotating ballnut mounts is more tricky.

kingcreaky
04-10-2012, 05:01 PM
Like that Idea, I noticed on Jonathons this idea was used, but disregarded its main advantage. This way I could buy, say 2m x 1m setup now. make the gantry 2m and the x axis x axis 1m. If its as successful as I hope I can then re-make the x axis longer. Need to think of a cunning way to make the rotating housings... I can worry about that at a later date. Going to start from scratch in sketchup again. this time with my newly quoted 60mm steel box from Adey Steel, and with the new design wide gantry and static screw.

blackburn mark
04-10-2012, 08:13 PM
spent most of last night laying awake. I get a bit like this when im 'on one' with something like this.

that's a good sign :)
its interesting and quite easy at the outset of any new design... in my experience though it gets harder the further you get into the nuts and bolts of the job... one small amendment can have a bitch of a knock on effect :(
its frustrating when you want to get building but try to design the knickers out of it before you commit because those amendments and knock on effects can be heart breaking if your half way through a build

having a Y axis that is longer than your X is pretty unconventional for obvious reasons... i can see your logic in expandability, if you will definitely expand if all works well i would keep the faith and go for glory at the outset on the proviso that the consensus was that your design would do what you required

iv not built a machine of that size but there are a few people on here that will give you a good idea if its doable 3m x 3m is quite a large machine... i'm not sure anyone has built one of that size on this forum ?

good luck getting to sleep lol

Jonathan
04-10-2012, 08:29 PM
3m x 3m is quite a large machine... i'm not sure anyone has built one of that size on this forum ?

I don't recall any that size here. You can get 3m long rails rails easily, but if you decide to use profile rails then it will be hard to align them over that distance. You're getting into mounting the rails on self levelling epoxy territory. The SBR series rails tolerate a lot more misalignment than the profile rails, so that option would be a lot easier and I'm confident you could make a strong enough machine that size to cut aluminium with them. The gantry clearly needs to be stronger than the current design if it is extended to 3m. You may want to consider placing the Z-axis between two beams with the rails on their inner faces.

With 3x3m you would also need rotating ballnuts on both X and Y. Just in case you've not already found it, there's some ideas about how to mount a rotating nut here (http://www.mycncuk.com/forums/linear-rotary-motion/3340-rotating-ballnut-design-ideas-4.html). It sounds like you might have a milling machine so as long as you've got a boring head or lathe you can make them.

WandrinAndy
04-10-2012, 08:41 PM
... in my experience though it gets harder the further you get into the nuts and bolts of the job... one small amendment can have a bitch of a knock on effect :( Its frustrating when you want to get building but try to design the knickers out of it before you commit because .....

Very true! That is precisely the design phase I have been wading through for the past many weeks, and it's very frustating but, with what I have discovered and had to correct in my little design, I'm very thankful to have found these problems before the build proper!

kingcreaky
04-10-2012, 11:49 PM
thanks for the comments gents.

however, although id love to build a machine 3x3. I cant afford too!. Im simply make the biggest I can whilst maintaining my marriage :D

anyway, done a bit more on the design. but those bearings look mighty small for such a large spanning gantry....

might have to have a re-think...

what do you guys think?7060

Jonathan
05-10-2012, 12:37 AM
I don't like the bed being unsupported over a 3m length. You can at the very least mount a piece of steel box section vertically at the back and the front, but the front one would have to be removed when you make the axis longer. A third piece of 3m long box section in the middle wouldn't go amiss either. Also I would make the bed bolt on to the 4 verticals on the other side, again to make it easier to extend the bed in the future. Currently the frame can 'skew' quite easily, since there are no triangles - so add some pieces to make triangles! You can do this in all 3 planes which is a good way of using up the left over box section since no doubt you'll be ordering in 7.5m lengths. Incidentally how much did Adey Steel quote you for the box section, presumably 60x60x3mm? Their pricing seems to be a bit random...

The way you have mounted the ballscrews is good since it allows adjustment of the height via moving the 4 pieces of box section, which is nice and strong. You can make the end mounts fasten to the box section via holes slotted horizontally to get adjustment in the other axis, which will help when aligning the ballscrews.

irving2008
05-10-2012, 01:02 AM
Some simple calculations can give you a better feel.

By way of example (and i'm not suggesting this is how to do it necessarily) lets say your gantry is a couple of 60 x 60mm x 3mm 2m long steel box sections joined by 3 bits of 10mm ali plate 200mm x 200mm at each end and the middle. The overall weight is 15.5kg and the deflection in the middle under its own weight, (ignoring the extra stiffness from the ali plates) would be ~0.1mm. A 10Kg spindle/z-package would cause a further 0.1mm sag, for a total of ~0.2mm. The max load on the bearings would be 255N which is nothing for a 25mm SBR. Increasing that to 100 x 60 box section with thicker walls would stiffen it further. Box section has its own issues with resonance but there are ways round that. The Y-rails would add further stiffness. All calcs are approximate and a more thorough analysis could be done.

So its doable... just need to get the detail right...

Jonathan
05-10-2012, 01:15 AM
I think if we included the torsional stiffness in the calculation then the results would be a lot worse. Once this 3m gantry is drawn I should be able to do a FE simulation to find how much it twists, rather like the one in this post (http://www.mycncuk.com/forums/faqs-problems-solutions/4356-why-not-use-unsupported-rails.html#post29195).

irving2008
05-10-2012, 07:25 AM
I think if we included the torsional stiffness in the calculation then the results would be a lot worse. Once this 3m gantry is drawn I should be able to do a FE simulation to find how much it twists, rather like the one in this post (http://www.mycncuk.com/forums/faqs-problems-solutions/4356-why-not-use-unsupported-rails.html#post29195).Don't disagree, my point was to illustrate that the bearing sizes were OK for a gantry of that scale. Of course it will need to be stiffer in torsion and I'd consider plates both side of the box section and some perpendicular as well.

kingcreaky
05-10-2012, 09:26 AM
Gents.

first of all, thanks you all so much for your input. You are all clearly much more astute than I. To be quite honest Im still pulling myself back together after reading Jonathons post http://www.mycncuk.com/forums/linear-rotary-motion/3340-rotating-ballnut-design-ideas.html about how one day he decided to manufacture the driven ball screw nut housings. That is on a complete other orbit to anything I have ever done / made.

Dont get me wrong. I have a metal lathe / miller of sorts
http://www.pensys.co.uk/images/lathe.jpg

but ive never made anything close to the type of engineering displayed by Jonathon in that post. To be quite honest its now making me doubt my ability to persue the static ballscrew idea.

So Im reverting back to the idea of spinning screw static nut.

Also, I can see where I went wrong in my blogs and I have mislead everybody. To be clear forget about 3 meters. the bed im planning to make will be at best 1700mm by around 1100mm

irving2008
05-10-2012, 10:00 AM
There's nothing wrong with that lathe/mill for aluminium as long as you're gentle with it (at least for the final cuts). Its a little harder to make by hand what Jonathan made by CNC (I suspect) but not impossible with some care. Like all things planning is key, understanding the order of processes etc. The engineering itself is relatively easy. What I find it best to do is draw it myself to help visualise the process. I know there are people that can look at a CAD drawing and machine it straight off but I find if I draw it in Sketchup the same way I would make it, i.e. start with a block and then remove bits, it helps visualise how.

Jonathan
05-10-2012, 02:02 PM
Whilst I did make the rotating ballnut housing with CNC, that didn't really gain anything except aesthetics. If you just don't bother with the rounded corners and change the pockets for the pulley/motor to rectangular instead of having rounded ends then the design is much easier to make manually (since it doesn't require a rotary table) and none of those things will affect its performance.


The difficult bit is boring the 70mm hole for the 7207 bearing since the lathe needs a lot of swing to accommodate the plate and also a large chuck or faceplate to hold it. However it seems your MF42B machine has 420mm swing, which is plenty. To avoid buying those you could machine somthing in the extisting chuck to hold them using the pattern of holes already present.You will of course have to run it slowly. The other option is to use a boring head in the milling machine. You could also make the bearing housing and motor mount separate parts. If you clamp the two halves together whilst boring them this will ensure the bearings are concentric when it is assembled.
I made the shaft for the first one on the manual lathe out of two pieces, which was a mistake as it's harder to fasten them together reliably and ensure the face upon which the ballnut mounts is normal to the axis of revolution. Instead make it from some 3" aluminium bar and take it slowly. When you get close to 35mm diameter for the bearing use very small cuts and keep test fitting the bearing as it needs to be very accurate. Also thread-cutting the shaft and using a locknut to pre-load the bearings turned out to be a much better solution.


To be clear forget about 3 meters. the bed im planning to make will be at best 1700mm by around 1100mm

So just to be clear, am I right in thinking you want 1700mm*1100mm working area, but the available space for the machine is 3*3m? If so then that's very close to my machine - 1700mm*740mm and you would be best just using rotating ballnuts on the 1700mm axis as the ballscrews will be about 2m long. It's possible to do it without, but you'll have to spend a lot more money on the motors and drivers to get similar performance. With two bearings at both ends of the ballscrew the critical speed of a 25mm ballscrew will be about 760rpm, so you could get 7.6m/min with an RM2510 ballscrew which is an acceptable feedrate but it is rather close to the limit so may not be very 'stable' compared to the rotating ballnut which allows at least twice that feedrate. The other option is to use RM2525 ballscrews, but again these are much more expensive.

r0bsk1
05-10-2012, 02:44 PM
This is excatly where i'm going with my machine simply because it'll suit my workshop more. My latest design has the longest axis of 2m on the gantry using 2 or 3 lengths of 60x60x5 stacked on top of each other with an ali back plate and using a rotating ballnut to drive it on a 2510 screw.
But then am i sacrificing rigidity of the machine just to make it easier for me to access.....?

blackburn mark
05-10-2012, 03:40 PM
To be quite honest Im still pulling myself back together after reading Jonathons post

take it easy man :)
be assured that most of us start pretty much where you are
i think some posters on this thread are being a tad unfair in flexing their intellectual muscles without remembering what its like to wade up to their neck in information and the inevitable burnout that causes... reminding you to chill should be on their list :)

you have a lath/mill so its safe to assume you are a practical bloke... if you have the gumption and time and a little help, nothing will stop you designing building a machine that will do as you require... it doesn't have to be rocket science and most machines are built without the in-depth mathematical analysis.

it wont be long before your the one sharing the love and helping some crazy arsed dude on a mission to build a cnc (just try not to melt his brain lol)

kingcreaky
18-10-2012, 10:37 AM
Hi All.

Quiteness is due to a lot of thinking, and sketching.

Towards the end of last week, I was put in touch with a guy who was selling a used "branded" machine, capable of cutting 8x4 sheets, with vaccum bed etc. It was going cheap due to all the electrics being shot. However, cutting a long story short I dont think its still a viable option, he was initially talking about a lot less money than he is now, then there is the logistics of moving it etc, and I dont think its going to be exactly what im after.

Im thinking 1400mm x 800mm x 300mm. with the conventional setup (having x being the widest axis) and having a shorter y. Unlike what I previously suggested earlier in this thread.

Being Realistic, I simply do not have the skills to be able to pull off a spun- ball screw nut. Manufacturing all the housing etc is just out of my depth. (as previously suggested), so my first question is

1,)What is the maximum length I can have, with a conventional 'spun-ballscrew' setup (keeping the nut static)?

I intend to have two screws for the x axis, (one on either side)

The ballscrews descibed in the ebay auctions (linearmotionbearings2008 (http://myworld.ebay.co.uk/linearmotionbearings2008?_trksid=p2047675.l2559)) detail as being 'end machined'

4 pcs of anti backlash ballscrews RM1605-350/800/1450/1450mm-C7(4screws+4ballnuts+4endmachined)
4PCS NUT HOUSINGS/BRACKETS FOR THESE 3 BALLNUTS
4 sets of BK/BF12 with locknuts and circlips+ 4pcs 6.35mm*10mm flexible couplers
Linear slide rails SBR20-600mm(2 supported rails+4 SBR20UU bearing blocks)
Linear slide rails SBR20-300/1400mm(4 supported rails+8 SBR20UU bearing blocks)


so with the 'flexible couplers' also supplied in the kit, I assume will fit my steppers ?
Nema23 Stepper Motor 3.1Nm x 3 (http://www.cnc4you.co.uk/index.php?route=product/product&path=83_84&product_id=66)

m.marino
18-10-2012, 12:24 PM
Have you thought about going vertical with this build? It would allow a good bit of what you seem to be wanting to do. It can limit the amount of part depth (item that you are working on) but there is always trade off's. As far as having pieces that need to be milled/machined, more then a few of us here are more then willing to help folks out in that area.

What do you want realistically for your machine?

What are you going to be using it for in the 1st yr (projects you can point to and have planned and are progressively more complex [trust me starting with really complex stuff does the head in])?

What do you want to do with the machine long term wise (upgrades and production levels)? This includes the budget for now and as well as a long the road of use.

Have you started costing out the software and tools to do work with? This includes the bits and such you will be using on the machine.

I am not trying to put you off or be a jerk, the information on this forum is staggering for many folks. Also there are a lot of folks who look at it and say "I want" without really counting the cost of getting there (trust me, why do you think I am on my second machine?). It is better to step back a bit design and work the design over hard and through away more then a few of them in the process, then to build with half an idea and end up costing you a lot more then it needed to.

My current machine does everything I need and when I upgrade the spindle (control or outright upgrade of the unit) then I will be able to cut materials beyond any need I really will ever have. The ting is my machine is part of business and Jazz/Dean helped by kicking into touch so many design ideas, as did other folks. Think the design out, not just use and parts but maintenance, where and how/wen upgrades or replacement parts can be dealt with. In doing so you are building a much longer usable life cycle into your machine and will get a greater return for your investment. To the folks who helped me and keep helping others thanks and I hope this pays forward a small part of the debt I owe.

Best of Luck and ask me if you need any help,

Michael

irving2008
18-10-2012, 01:08 PM
...[stuff]

1,)What is the maximum length I can have, with a conventional 'spun-ballscrew' setup (keeping the nut static)?

I intend to have two screws for the x axis, (one on either side)

The ballscrews descibed in the ebay auctions (linearmotionbearings2008 (http://myworld.ebay.co.uk/linearmotionbearings2008?_trksid=p2047675.l2559)) detail as being 'end machined'

4 pcs of anti backlash ballscrews RM1605-350/800/1450/1450mm-C7(4screws+4ballnuts+4endmachined)
4PCS NUT HOUSINGS/BRACKETS FOR THESE 3 BALLNUTS
4 sets of BK/BF12 with locknuts and circlips+ 4pcs 6.35mm*10mm flexible couplers
Linear slide rails SBR20-600mm(2 supported rails+4 SBR20UU bearing blocks)
Linear slide rails SBR20-300/1400mm(4 supported rails+8 SBR20UU bearing blocks)

so with the 'flexible couplers' also supplied in the kit, I assume will fit my steppers ?
Nema23 Stepper Motor 3.1Nm x 3 (http://www.cnc4you.co.uk/index.php?route=product/product&path=83_84&product_id=66)

Given the BK/BF mountings you have a fixed/supported arrangement (supported BF at the far end, fixed double BK near the stepper) the critical speeds are:

350mm:10000rpm (lots of m/min)

800mm: 1965rpm (9.8m/min)

1450mm: 598rpm (3m/min)

To get closer to 6m/min on X you either need 10mm pitch screws, or you need to increase diameter to 25mm but then the inertia of the screws is going to be limiting on acceleration.

Another option is to upgrade the bearings to be double angular bearings (BK) at both ends. This will increase the critical speed to 880rpm (4.4m/min), better but still not great.

Here is a good PDF that shows how these are assembled: https://tech.thk.com/en/products/pdf/en_a15_314.pdf

And the critical speed calculator is here: http://www.nookindustries.com/engineering/calculators/CriticalSpeedMetric.cfm?Root=13&Length=1450&C=1.0&RPM=598&reset.x=0&reset.y=0


Couplers are fine: 6mm stepper shaft to 10mm end machined screw.

kingcreaky
18-10-2012, 02:32 PM
now I am confused! I think im going to have to read your post another 100 times slowly to understand, then study the pdf. perhaps im not asking the right questions? or perhaps relying too much on telepathy
Essentially you have succeeded in making me aware there are different 'types' of ball screw housings. I think what your saying is the ones ive detailed above (which incidently I havent yet bought anything) are for a fixed screw arrangment, and if I want a spinning screw I need to re-think my choice of screw housing? once again, one question results in ten more :D sorry :ambivalence:

Jonathan
18-10-2012, 07:03 PM
As irving has said, you need to use 10mm pitch (RM1610) ballscrews on the X and Y axis to get respectable feedrates without using a larger diameter ballscrew.

Clearly it depends on what the minimum feedrate you can accept is, but I wouldn't go above a 1500mm long RM1610 ballscrew without using a larger diameter screw or rotating the nut. If you're interested I can make the rotating ballnut mounts for you, let me know if you wanted the details. I wont be able to make them any time soon, but it looks like it will be a while until you're ready anyway.

The 3Nm stepper motor shafts are 8mm, so you would need 8mm to 10mm couplers. However I would strongly advise using timing belts and pulleys since this enables adjusting the drive ratio to get better speed or resolution with the added bonus of adding damping to the system to suppress resonance.

irving2008
18-10-2012, 09:35 PM
now I am confused! I think im going to have to read your post another 100 times slowly to understand, then study the pdf. perhaps im not asking the right questions? or perhaps relying too much on telepathy
Essentially you have succeeded in making me aware there are different 'types' of ball screw housings. I think what your saying is the ones ive detailed above (which incidently I havent yet bought anything) are for a fixed screw arrangment, and if I want a spinning screw I need to re-think my choice of screw housing? once again, one question results in ten more :D sorry :ambivalence:

Nooo... Imagine the screw is a long bendy pole... the faster you twirl it the more it flaps around. To stop it flapping you need to constrain it. The way to do that is to put bearings at each end. The bearings are fitted into bearing housings. The one at the far end has a single bearing in it, the one nearer the drive end has two bearings. The single bearing just supports the screw, it doesnt stop it moving end to end (axially). The double ones stop the screw moving end-to-end, hence 'fixed'. Both types allow the screw to turn! By putting a 'fixed' one at the far end as well controls the whip a bit more but it needs a different end-machining of course.

kingcreaky
31-10-2012, 10:53 PM
this really is like a mind boggler. ive spent pretty much every waking moment, reading posts, writing notes but mostly thinking. Oh, and getting frustrated with google sketchup.
I have made a final, firm decisions on a few things.
*It will be around 1.5m by 1m
*after reading the pros and cons, and weighing them up in my own head, Im using chai's supported bearings SKB16, maybe 20's for the gantry to slide along on(is that the X some people call it X some people call it Y)
*The first version, Il use the 1610 ballscrews I think that is what Irving is trying to suggest in his above posts) , and although maybe not recommended il spin the ballscrew not the nut. I may eventually re-think this once ive learnt from my mistakes. As Il be driving the ballscrews with timing belts I can gear it so they for optimal reliability not speed.

I am very confident with steel. I can weld well, (although I understand the issues over warping) so please see my gantry design.

Ive read thread after thread explaining the importance of keeping the gantry supported to stop flexing. I also appreciate the ultimate goal is keeping the cutting tip as close to the center of the gantry as possible through organising the Y and Z axis /ballscrew configurations.

With the comment over confidence in steel and no experience in extrusion or ali whatsoever, please see my current gantry plan (attached?)

as you can see, ive used two peaces of 50x200x6 I intend to triangulate the back for extra support and place the Y bearings one at top and one at bottom (top marked in red)

In terms of fixing the material together, I think im going to carefully weld it.

I need your thoughts now, Ive heard Jonathon banging on about steel box not being 'straight' and I should probably be using ecocast ali. or even extrusion like some of the builds here. Without entering into yet another full on discussion over gantry design. is carefully welding the steel going to distort it that much the z unit wont slide the length of the gantry without binding?

should I use extrusion?

With extrusion... how do you know the t-slots or slots in the extrusion are going to line up with the pre-drilled holes int he supported rail?

where do I buy extrusion?

totally consumed in this, and seeking some support!

m@

WandrinAndy
31-10-2012, 11:57 PM
I'm also new to this KingCreaky, so can only try help a wee bit...

For this size machine which is similar to the size I'm designing, choosing 1610 ballscrews seems spot on, but I think the gurus are likely to suggest 1605 only for the short Z-axis. And spinning the ballscrew rather than the nut is the default norm.

If you're gonna use supported round rail I think the gurus would suggest Chai's SBR20 rail.

Where peeps do use extrusion, a version of 45x90 extrusion is popular on this forum that hails from your neck of the woods... KJN in Leicester... Aluminium Profile with 10mm Slot (http://www.aluminium-profile.co.uk/acatalog/Aluminium_Profile_with_10mm_Slot.html)

The KJN 45x90 extrusion has slots that are well suited to the precision-profile-rail that is terribly pricey, but not particularly suited to supported round rail.

Hope this helps.

JoeHarris
01-11-2012, 12:12 AM
I am working on a similar sized machine and have been through the same questions on ball screws - seemed to me there was a lot of different opinions floating around. I too decided that spinning ballnuts was a bit out of my league! I went for 2005 in the end, the larger dia will hopefully help with whipping and I am going to gear it 2:1 so as to get faster feed rates, with the option of gearing 1:1 for high res work...

I am coming round to the idea of using steel (ill have to learn to weld tho!) for the frame and x axis but Ali extrusion does seem the best option for the gantry. The L shape arrangement used in a few builds allows you to keep the gantry squat and rigid. Why does your gantry need to be so tall and thin...?

If you need any help with sketchup just ask I have been using it for years and have just about got through the pain in the ass stage !

Jonathan
01-11-2012, 12:34 AM
I went for 2005 in the end, the larger dia will hopefully help with whipping and I am going to gear it 2:1 so as to get faster feed rates

Not really, you'll end up worse than with 1610 regardless of the drive. Critical speed is proportional to the diameter, so going from 16 to 20 means the ballscrew can rotate 25% faster. However to get the same feedrate with 5mm pitch (2005), you need to spin the screw 100% faster, but can only go 25% faster... so you end up with 62.5% of the feedrate attainable with 1610.

If the L-shape gantry is reinforced by putting some box section on the back at 45 to make triangles it will be very strong.

JoeHarris
01-11-2012, 09:43 AM
OK but surely it depends on the speed you need. I remember reading on another post that Jazz gets no whip running his 1500mm 2005 up to 12meter/min... Plus you get greater mechanical advantage with a smaller lead? Well I have bought mine now so when I have built the machine I will be able to report - Just hope I will get enough speed to cut ply without burning it up!!

Jonathan
01-11-2012, 03:35 PM
OK but surely it depends on the speed you need.

Yes, if it's sufficient and the motors can drive it at that speed you're fine. But that's the other issue, you will need significantly more torque from the motors to obtain the same feed-rate/acceleration as with the 16mm screw since it is not a linear relationship, power 4 in fact, so for a given acceleration you need (20/16)^4=2.44 times the torque. So if at the speed/acceleration you would have run the machine on with the 16mm screw you have that much spare torque then it would be fine with 20mm, but it's a shame because you would definitely have got better feedrates with the 1610 screw and it's added an unnecessary risk.

For a 1500mm 2005 screw the critical speed is about 1200 rpm with the standard bearing arrangement, so 1200*5=6m/min feedrate.
For 1610, same length etc, it's about 1000rpm, so 1000*10=10m/min feedrate.

From experience the formula used here seems to be conservative, so that is probably enough assuming the motors you have can actually output enough power to achieve that feedrate.


Plus you get greater mechanical advantage with a smaller lead?

True, but you can use the pulleys to get whatever mechanical advantage (i.e. ratio) you want, so it's a bit of a moot point.

kingcreaky
08-11-2012, 10:39 PM
73487349735073517352

kingcreaky
08-11-2012, 10:40 PM
Gentlemen.

I think hope that I am nearing the end of the design stage. I genuinely need to start ordering in order to finish the design now. Can I trouble you with casting your eyes over what I hope to be my final table and gantry design.
I have at present omitted the Z axis, or properly finished the Y. Mainly because until I have the bearing houses and rails in my hand, to measure them.(I appreciate the sites give dimensions. But) until I can bite it, Im not confident enough in my drawings.

Therefore I need some help before I approach linearmotionbearings2008 is it 'Chai?' for a quote on the bits I need.
Based on what ive previously explained. I wish to have spinning screws, rather than spin the bearings. (for now). This is mainly due to my present ability. I'm going to go for RM1610 screws (under recommendation). I never did understand irvings point within his post on p.21 when he refers to

"Another option is to upgrade the bearings to be double angular bearings (BK) at both ends. This will increase the critical speed to 880rpm (4.4m/min), better but still not great."

so, BK is like a bearing (next to the driven end of the screw) and BF is designed just as a support. I assume the BK end needs to be machined to fit the bearing, and the BF is non-machined.

His point is simply it would be better if I have BF style at both ends. and therefore get each end screw machined to suite?

So, based on my design. I will need
(X Axis)
* 2 x RM1610 (1500mm) screws (machined at both ends, one side will need to be machined to fit through the BF bearing and also so I can fit a driven pulley, and the other needs to be machined simply to fit the BF bearing. Im assuming I just let Chai know that I want to fit a pulley so he leaves enough shaft after the bearing housing. then I just by a piloted pulley and bore it to fit the machined end of the screw?
* 4 x BF bearing with supported block mouting
* 1 x ballscrew nut (quite tempted to make my own housing for this)
* 2 x SBR20 fully supported rail (1600mm) (with 4 bearing blocks) I assume SBR20UU


Y Axis
*1 x RM1610 Screw (1000mm) (same question as above)
* 2 x BF bearing with supported block mouting
* 1 x ballscrew nut (quite tempted to make my own housing for this)
* 2 x SBR20 fully supported rail (1000mm) (with 4 bearing blocks)

Z Axis
* 1 x RM1610 Screw (300mm)
* 2 x BF bearing with supported block mouting
* 1 x ballscrew nut (quite tempted to make my own housing for this)
* 1 x SBR16 fully supported rail (300mm) (with 4 bearing blocks)

Right, now I have satisfactorily embarrassed myself with incorrect terminology can somebody tell me if the above sounds about right? Or have I completely misinterpret ted anything?

while im asking the question.

assuming Im not bothered about speed initially. Therefore Id prefer to gear everything at a higher resoloution 1 turn of the stepper, means 1/2 a turn of the ballscrew. Therefore the pulleys on the ballscrew need to be twice the diameter of the pulley on the stepper.
so something like
10XL037 Flanged Timing Pulley :: BearingBoys.co.uk (http://www.bearingboys.co.uk/10XL037_Flanged_Timing_Pulley-20917-p)
for the steppers
and
16XL037 Flanged Timing Pulley :: BearingBoys.co.uk (http://www.bearingboys.co.uk/16XL037_Flanged_Timing_Pulley-20922-p)
for they the screws?

The steel on the frame is mainly 60x60x3mm which I may get ordered so I can begin building the frame.

Id appreciate your thoughts.. negative or positive.

Jonathan
08-11-2012, 11:21 PM
RM1610 is good for X and Y since the higher pitch means you can get a higher feedrate with limited critical speed, however since the Z-axis screw is so short there's no need to do this, so stick with RM1605 on Z to maintain good resolution.

I advise using bigger rails on X and Z. Particularly Z since the forces on Z are a similar magnitude to Y, so you shouldn't use smaller rails.

For a 1:2 ratio you don't want 10:16 pulleys for two reasons - for a start 16/10 is 1.6 not 2, and also it's not good to have such small pulleys as you will have less teeth engaged in the belt which can lead to premature wear and possibly reduced accuracy. It's best to use at least 15T, so 15:30 would be good. Also HTD pulleys are better than XL.

The BK and BF mounts both hold bearings, the difference is the type and quantity. BK has two angular contact bearings inside, which means it can resist both radial and axial loads, whereas BF just has one 'standard' bearing in it, so only supports the ballscrew radially. If I were you, since you have the lathe, I'd make my own bearing mounts from aluminium. It's not that complicated and you'll be able to do a much better (and cheaper) job of it than the ones from China. They are often too tight a fit, or the seal rubs on the nut or other annoying thins to correct. I've never bought the BK/BF blocks myself, but I know people who have and they've all needed tweaking.

Also making your own ballnut mounts is a good plan simply because it's so much cheaper. Here's one I made earlier:
7353

kingcreaky
09-11-2012, 09:13 AM
Jonathon, Jonathon... How on gods green do I even start thinking about making something of that caliber? they really are amazing. But I am a realist as much as I could probably make one, if I set my mind to it. The other 7 just wouldnt be the 'same'. :-D Just looking at them, their accuracy makes me feel sick. Its one of these situations where I need to see them before I know what Im doing... For example you have mentioned seals, Ive heard circlips mentioned. All of this is assumed knowlege that you guys have gathered from building a mk1 machine first. And I think ultimately this is what I am going to have to do.

An example, if I need 1500mm of drivable screw. (inside the supports) then how do I calculate how much 'extra' I need at either end to go through the housing (your suggesting I do not buy from the same supplier), and also through the support on the other side and through a pulley that I also havent bought!. This is why (I guess) for me it may be easier to just buy the supported bearing housings from the china supplier and if necessary re-make them based on the design on the ones that come with the screw? (can you see my thought pattern?) On previous threads on here I noticed your original build thread for your first machine. This machine was significantly different to your present one, and I guess you learnt from your mistakes on that build to gain the knowlege you have today?


You say i should upgrade my X axis rails, they are already SBR20... what is an upgrade to them?

So, taking on board your comments, a modification to the shopping list would be

(X Axis)
* 2 x RM1610 (1500mm) screws (machined at both ends, one side will need to be machined to fit through the BF bearing and also so I can fit a driven pulley, and the other needs to be machined simply to fit the BF bearing. Im assuming I just let Chai know that I want to fit a pulley so he leaves enough shaft after the bearing housing. then I just by a piloted pulley and bore it to fit the machined end of the screw?
* 4 x BF bearing with supported block mouting
* 1 x ballscrew nut (as above re housing)
* 2 x SBR20 fully supported rail (1600mm) (with 4 bearing blocks) I assume SBR20UU


Y Axis
*1 x RM1610 Screw (1000mm) (same question as above)
* 2 x BF bearing with supported block mouting
* 1 x ballscrew nut (as above re housing)
* 2 x SBR20 fully supported rail (1000mm) (with 4 bearing blocks)

Z Axis
* 1 x RM1605 Screw (300mm)
* 2 x BF bearing with supported block mouting
* 1 x ballscrew nut (as above re housing)
* 1 x SBR20 fully supported rail (300mm) (with 4 bearing blocks)

Although your comments re-pulleys is useful. Its another answer that fills my head with more questions... I think il put off buying pulleys until I have stuff on the workshop floor I can bite.

I genuinely really appreciate your thoughts, Im absorbing as much as I can. Your clearly an immensly clever lad but Im just a normal bloke!. The entire point of me building a machine is to be able to get to a point where I can make 'things' more accurate, Its a chicken and egg situation. If I had a rig, this rig build would be as easy as you make it sound!

Jonathan
09-11-2012, 04:35 PM
But I am a realist as much as I could probably make one, if I set my mind to it. The other 7 just wouldnt be the 'same'

I very nearly captioned that photo with 'can you spot the mistake'!


. :-D Just looking at them, their accuracy makes me feel sick. Its one of these situations where I need to see them before I know what Im doing

They're a copy of a common design on eBay. I started with 2" square aluminium bar, used the lathe to face both sides and bore the hole in the middle. Next I milled two opposite sides to the correct size using a fly-cutter (hence the nice finish). I then spotted and drilled the holes using the milling machine by just moving to the correct co-ordinates for each hole and finished off by milling the other 2 sides and the corners. The milling was done using CNC and g-code written then saved as I went along, but it could just as easily be done manually. I could have started with aluminium bar closer to the final size to save some milling, but since my lathe has a 4-jaw self centering chuck it's more convenient to use that than get a load of rectangles on centre with the 4 independent jaw chuck.


... For example you have mentioned seals, I've heard circlips mentioned.

The BK block has a rubber shaft seal on both sides to help prevent swarf etc getting into the angular contact bearings as that would rapidly destroy them. There is a groove for a circlip on the other end of the ballscrew, which doesn't seem to achieve much.


An example, if I need 1500mm of drivable screw. (inside the supports) then how do I calculate how much 'extra' I need at either end to go through the housing (your suggesting I do not buy from the same supplier) ... easier to just buy the supported bearing housings from the china supplier and if necessary re-make them based on the design on the ones that come with the screw?

I'm suggesting you do, but it's not compulsory by any means! Clearly you can get the standard mounts to work, it just may require adding shims between the bearings, machining a spacer so that the nut doesn't rub on the shaft seal and possibly opening the bearing bore out a little so that the bearings are not too tight a fit. Or they might be fine. To me that doesn't seem worth it when I can just make my own and know it's going to be accurate from the start, in addition to gaining flexibility with the design and learning something the process. You will need to have a look in other threads about how to make them - the drawings are readily available.


On previous threads on here I noticed your original build thread for your first machine. This machine was significantly different to your present one, and I guess you learnt from your mistakes on that build

Short answer is yes. My initial machine was constrained significantly by the cost of getting the proper components, hence I tried to make as much as I could to save money. Everything between the X-rails (so Y and Z-axis essentially) hasn't changed since the first build. I just removed the silly tall gantry sides and made a better frame. I'm glad I did it this way since it forced me to try new things, such as using a bearing riding on a threaded rod to make a cheap drive with negligible backlash.


You say i should upgrade my X axis rails, they are already SBR20... what is an upgrade to them?

SBR25, or minimum 15mm profile rails (linear guides). Latter is a bit too expensive though.

Get the Y and Z ballscrews with the standard end-machining since they are quite short, so critical speed is not a problem, but do ask Chai to increase the length of the cylindrical portion on the fixed end of the screw (dimension F on his drawing) from 15mm to 25mm to accommodate the pulley.

Since the X-axis ballscrew is quite long, to get the best feedrates you can put a pair of angular contact bearings on both ends, so you could get the ballscrew machined the same on both ends.

Here are the standard end-machining drawings from Chai:

7357

You can see from those how much 'extra' length you need for each ballscrew. If you ask Chai for RM1610-1000mm for instance, he will machine it such that the total length is 1000mm and the actual ballscrew is 924mm with F increased to 25mm.


The entire point of me building a machine is to be able to get to a point where I can make 'things' more accurate, Its a chicken and egg situation. If I had a rig, this rig build would be as easy as you make it sound!

The thing is you have got the machine to make this machine. When I decided to make my CNC router I had a milling machine and mini lathe, so I used those to make all the parts, such as bearing blocks and ballnut mounts and thus have never had to pay anyone to make bits for me. I did mill the Z-axis plate square on the school Bridgeport milling machine, but that was mainly just for aesthetics.

kingcreaky
14-11-2012, 02:24 PM
ok, bits ordered (warning: communication with chai is a bit difficult, generally a one day delay with every message due to time zone) then, when you do get a reply its questionable if he has undertood your meaning).

X Axis
* 2 x RM1610 screws(1603mm Total length) I need (1500mm) of screw, so 1500mm PLUS one end machined to type A (except dimension F to be 25mm instead of 15, and the other end machined again to type A, but without any F
* 4 x BK12 fully supported bearing with supported block mouting
* 2 x ballscrew nut
*2 x SBR25 1600mm fully supported rail with 4 bearing blocks

Y Axis
*1 x RM1610 Screw (This one, id like the TOTAL length to be 1000mm, but one end machined to type A (except dimension F to be 25mm instead of 15, and the other end machined again to type A, but without any F
* 2 x BK bearing with supported block mouting
* 1 x ballscrew nut
* 2 x SBR20 fully supported rail (1000mm) (with 4 bearing blocks)

Z Axis
*1 x RM1605 Screw (This one, id like the TOTAL length to be 300mm, but one end machined to type A (except dimension F to be
25mm instead of 15, and the other end machined again to type A, but without any F
* 2 x BK bearing with supported block mouting
* 1 x ballscrew nut
* 2 x SBR20 fully supported rail (1600mm) (with 4 bearing blocks)


So, I now have some momentum. Im a few hundred quid lighter. But most importantly the ball is rolling. So now not just out of my depth :D BALLS DEEP and out of my depth.

Just have to wait for my contact to return from South Africa, to make an order for the box section to commence making the table. (hopefully will have this by the end of next week (mon 19th)

I have soo many questions, Ive tried my hardest to research them before asking, but straight answers from the experienced is so much easier! as often you go off and read something, then come back here and read contradictions and end up banging your head against the wall and opening another beer.

So some questions gents. First one; what am I searching for in order to get videos, detail etc on the process of software behind creating a work-peace once the machine is made. Is there such thing as a machine simulator? I understand Mach3 simply takes an input file.. a dxf? So I can draw the workpeace in autocad {if i had a licence} -- what about sketchup?. What is and why do people use solidworks?

Second One;
Anybody want to face inevitable persecution and real off a list of recommended electronics? or maybe even just the electronics your using so I can copy!. I have previously mentioned what steppers I have,

Nema23 Stepper Motor 3.1Nm x 3 (http://www.cnc4you.co.uk/index.php?route=product/product&path=83_84&product_id=66)

I understand the trick is more voltage to the stepper the better.

I read good things about these Leadshine AM882's for controllers.... anygood? thoughts?

can anybody suggest anything better? Realistically, im not going to build my own power supply to then plug it into the hundreds of pounds worth of controllers ive just bought.... il just spend a little bit more a buy a power supply aswell. Reccomendations?


then, the other big question is breakout board... /controller board. I like the idea of one of these Cat5 units (as my computer is firmly mounted in workshop and usb and parrelel has a finite distance)


Finally, if I use 3mm steel box section. Im going to need to drill and tap it to accept bolts that will affix the linear rails etc. Therefore is 3mm thick enough?


look forward to your replies.

Once my machine is done, and I have used it a few times. The next thing Is I plan to hold an open evening. All will be invited to my workshop for coffee and cakes. The idea being anybody who (like me) is just coming into this, feels ridiculously out of their depth, and wants to see a machine work, see the process from start to finish and ask limitless stupid questions and get straight answers can attend! You all Watch this space :-D

r0bsk1
14-11-2012, 03:52 PM
Just a heads up......I ordered 4x 1200mm SBR25 but received them measuring 1210mm. They must have better value tape measures in China!

kingcreaky
15-11-2012, 08:29 PM
For all that are interested. Finished design.

JoeHarris
15-11-2012, 08:36 PM
Looking good, how are you connecting the steppers to the frame?

kingcreaky
15-11-2012, 08:49 PM
hey, thanks for the reply!

I see "you lot" mill out these sexy pocketed aluminum peaces of art. take a photo stand back and say 'that'll do'. I dunno glue? bluetac? nails? :hysterical:

Il probably make some steel brackets initially until I become a certified wizard.

kingcreaky
19-11-2012, 11:06 AM
7413
Morning All. Monday again :(

So, suppose I have the two peaces of 45x90 Ali Profile in my hand now.
I want to arrange them in the above formation.

Is there any product that enabled me to mount them together in this way (rather than a 90deg bracket at the back)

You would think there would be a fillet strip that runs in the 10mm extrusion that runs alongside the two peaces. Then obviously I could nut and bold aswell...

also, im keen to use 45x90 (only because thats what my design uses, and that was only because I was recommended to use KJN in leicester so I used a product from their range on the website. Now when I actually need to make an order. they neither answer the phone or email. So can anybody recommend a different supplier. Ive seen the sponsored link off here to 'metallin' however then dont do 45x90

so need answer too two questions

1.) How do I join to peaces of excursion together in the above formation?
2.) can anybody recommend a different supplier?

asbo
19-11-2012, 11:23 AM
I was recommended to use KJN in leicester so I used a product from their range on the website. Now when I actually need to make an order. they neither answer the phone or email.
Why not just order it via their website? KJN - Suppliers or Aluminium Profile and Accessories (http://aluminium-profile.co.uk/)

kingcreaky
19-11-2012, 11:44 AM
Why didnt I think of that? :D

I want to ask them about fixings... basically question no.1 above. Like I say, short of going their and knocking on the door ive tried everything.

asbo
19-11-2012, 03:59 PM
I think I'd put a T-nut(red) in the bottom of the top extrusion and then drill a hole up through the bottom extrusion and bolt(blue) them together.
See my super accurate diagram :D
7417

maybe you'd also want a piece of plate along the back bolted to both pieces of extrusion. I'm no expert though.

Also I'm surprised by their lack of response, they sent me some free design software before I even bought anything. I just used the Contact Us form on their web page.

kingcreaky
19-11-2012, 04:08 PM
hey, thanks for taking the trouble to do that for me... I now have a response from KJN

"The way we would recommend that the profiles be joined would be to Drill and counterbore through and use a Slide blocks in the slot and Caphead to tighten."

Which, I think, is exactly what your saying. Il order it with some t-nuts and see how i go

asbo
19-11-2012, 04:21 PM
Happy to help :)
Yep pretty much, although the sliding blocks they suggest are probably better since they spread force out over a larger area. It might be a case of experimenting to see what works best.

Jonathan
19-11-2012, 06:27 PM
I'm not keen on how far the Z-axis overhangs (parallel to X). Presumably you've done that to position the Y-axis ballscrew more optimally than having it on the back, a long way from the cutter? That's sensible, but I would at the very least try and add pockets to compact the design, or add a second piece of extrusion above the existing one such that the ballscrew can run between the two, i.e. directly between the rails which is optimal.

kingcreaky
26-11-2012, 06:44 PM
BOOM
7468

520 worth of Chai's finest have arrived today. What a nice surprise after an entire Monday at the office.

asbo
26-11-2012, 09:46 PM
Nice, I bet the delivery man was struggling. I had difficulty lifting my parcel from Chai and I got less than you!

kingcreaky
27-11-2012, 06:05 PM
The lovely delivery man brought more goodies from China today

747374747475

No idea how to wire this lot up...

Hopefully take delivery of my 500w linear supply from Zapp tomorrow

PS806-5 Linear power supply. (http://www.zappautomation.co.uk/en/power-supplies/438-ps806-5-linear-power-supply.html)

ohh, and my metal man delivered yesterday aswell!

kingcreaky
28-11-2012, 10:06 AM
your a talkative bunch on here arent you!. :-D

Anybody able to point me in the right direction of a thread that details information about wiring this gear up.... and a base set of configuration jumper settings etc? I am genuinely very confused!

the drivers and breakout: Wholesale Product Snapshot Product name is Cheap CNC! Wantai 4 PCS Stepper Motor Driver DQ860MA 80V 7.8A 256micro CNC Router Mill Cut Engraving Grind Foam Embroidery (http://www.aliexpress.com/snapshot/207335054.html)

Also as the parrelel cable is only about 1.5 meters long... and the computer is about 3 meters (crow flies, 6 meters cable run) from the machine shall I put the control circuits next to the computer then have LONG wires to the steppers / limit switches... or... perhaps put the breakout board near the computer and have LONG cables from that to the drivers and power supply (which is at the machine) your opinions will be very welcome

also... what cable is good for long runs; I like the idea of like multicore sheilded wire; id got car trailer wire in mind but it appears its only rated at 7amp which is no use I guess?

box of chocolates in the post to anybody who helps me :-/

mocha
28-11-2012, 05:27 PM
They're all too busy building! :-)

I'll claim the chocs tho, "CY" is the evolved option of choice for cable that has floated to the top, have you seen how bad trailer hookup wire gets after it's been used for a while? not good! For loads of info on wiring and the laws of electrickery, have a search through some of Irvings' posts... all that thee seeketh thou shalt surely find! :-) dig up the stuff on earth practices especially.

Right, back to Sketchup for me!

Tom
28-11-2012, 05:44 PM
Hello kreaky,
Good to see bits turning up.

About your cable Qs. I would put the control box near the PC. The voltages in the parallel port cable are low (3.3 or 5v), whereas the cables from the drivers to the motors are high (80v or so by the look of your power supply) so will travel better. You WILL need shielded motor cable. I had terrible problems with low voltage limit switches tripping due to interference before I added shielded cable. My motors only run at 37v too (from memory).

blackburn mark
28-11-2012, 07:37 PM
I see "you lot" mill out these sexy pocketed aluminum peaces of art. take a photo stand back and say 'that'll do'. I dunno glue? bluetac? nails? :hysterical:

Winner! :hysterical:

shit!! you didn't hang about
you'll be standing behind a wall wincing your eyes and pressing the "ON" button in no time :)

Lee Roberts
28-11-2012, 08:03 PM
Looking good King Julian (look he's a lady !!!)

Yea shielded cable from the start and short cable runs when you can.

.Me

kingcreaky
01-12-2012, 07:33 PM
Right then gents

a productive day... Good friend of mine lent me the use of his unit... which was invaluable square warm space with all the kit to hand to make the job of making the frame easier.

Not to mention a fork-lift to load it onto the trailer to bring it home!. My god its heavy.

60x60x4 box & 60x100x5 box

Very pleased with my welding.. Proud enough to upload a piccy. Got so used to welding on crappy tin underneath cars welding nice clean think steel was a dream!
7498
and finally; back to my comparably dark and dingy untidy workshop.
7499

"I have a new crown"

Lee Roberts
01-12-2012, 10:24 PM
Looking good Julian, looks like your mates unit is the business!

Welding up cars made of tin....I hear that, how comes you dubbled up on the top rails ?

EDIT: Scrap that question just went back to post #31 for a recap !

.Me

kingcreaky
02-12-2012, 10:13 PM
ok taking on board jonathons comments; ive redesigned Y gantry to bring Z closer. feelings on this?

ive also taken the sound advice of a very nice chap; who pointed out I should add some extra bracing at the top to reduce resonance; At present I can only guarentee space for the yellow peace... I need to think of a cunning place to put one at the other end. the obvious place would be between the two 60x100's however that is going to be RIGHT in the way

Ive also added the red-blocks... the idea of this is to support the bed bolts further. Its suspected the bolts will move and the bed will constantly go out of true. Therefore the idea of these is to re-inforce.
75037504
however, ive since had a brain wave.. stand back. the idea of the multiple holes on each leg is so the bed can be lifted and dropped. well... how about instead of the small red peaces; I have 6 metal peaces pre-cut same length per height adjustment... so imagine the red bit going all the way down to the horizontal cross bracing.. only drawback to this idea is that I need 6 bits per desired hieght; but the advatage is the plunge force onto the bed is directed down onto the horizontal beams (which in the drawing are represented as 30x30; when infact they are 60x60x4's


eagle eyes amongst you will also notice ive switched the Z screws round (so the belt and stepper is at the other end).

anyway; been building cnc all day yesterday and new shed all day today (long story) in the freezing cold; Time for a beer and to fall asleep in front of the telle

work tomorrow.. dredd.

Who can I Pay to supply cut and machine all ali plate bits for the Z and Y this side of xmas? none of them are complicated no pocketing. just straight cutting (well straighter than me and my angle grinder can do!)

kingcreaky
10-12-2012, 07:43 PM
Hi All.
Im aware that mounting the ballscrew behind the face is a compromise, however. Based on the gear ive got here I cant pocket therefore this is my final gantry design.
The gantry is made of two 60x100x6 Ali Box Sections bolted together.

The Y face plate is 160mm wide

before I spend a sh*t tonne of money with Aluminium Supplier | Aluminium Stock | Aluminium Warehouse (http://www.aluminiumwarehouse.co.uk) (excess 200) on ali; can somebody tell me any good reasons why this wont work (it maybe revised at a later date once the machine is made)

also; do you think ecocast is necessary for anything other than the front plate... for example the top & bottom bits and the back plate can surely be 6082?

thanks in advance for the influx of replies...

75777578
^^ or... turn it round? so the Y plate is at the back?

Jonathan
10-12-2012, 08:26 PM
Make the 4 joints on the Y plates the other way round, otherwise you can't adjust the vertical spacing of the Y-axis bearings to account for any error in the box section dimensions.

You don't really need eco-cast for these parts, so long as you use cut aluminium plate not flat bar since the error on plate is tolerable when you're only using round rails.

Edit: You could also make the plate on the back thinner as it doesn't contribute much to the overall strength.

njhussey
10-12-2012, 09:26 PM
Just one thing I've seen, can you not shift the Y axis to the back of the bearings so the Z axis is nearer the front bearing, looks like you've got the gantry sitting on the front bearing rather than the back?

Wobblycogs
11-12-2012, 11:01 AM
You've come up with almost exactly the same design as I did, even down to the materials you've selected. I've switched back to using extrusion though as it's simpler to mount to the gantry sides and I couldn't think of a good way to bolt the two pieces of box section together.

One thing I would add to the comments already made is, depending on the travel of your Z-axis, you might want to make the front plate a bit taller to give yourself a better spacing between you Z-axis bearings. Once you've switched the joints around it's easy to make the change just for the fairly small cost of the metal.

kingcreaky
11-12-2012, 11:14 PM
thankyou all for your replies.

Think, i have taken upon your ideas with my new design... although not sure if I understood Neil's post..

anyway... Ive ordered the bits... notice the 5mm plate that runs the length of the gantry in front of the two box sections to aid strength once fixed together. consequence is ive had to move the Y plate 5mm further away.. not sure if im gonna use it but ordered it anyway

202 with AW!!!

current expendature: 1282

still to buy.. wiring from steppers to control case, control case ancillaries (connector blocks, cut off switch fans etc) pulleys, belts and 2.2kw spindle

njhussey
11-12-2012, 11:37 PM
Ok...time for one of my Tony Hart drawings ;)

This is what I was trying to say....to me it looks as though you have the gantry over the front rail, this causes a large overhang of the Z axis and is far away from the bearings. Top scribble.

If you move the gantry so it sits over the back bearing there will be less of an overhang and it will be better. Bottom scribble.

7592

Wobblycogs
12-12-2012, 11:37 AM
If I could make another suggestion, add all your bolts and other fixings to your design before starting cutting. A couple of parts I've designed I've been happy with only to discover that I can't then bolt them together or the bolt holes would be too short to have any strength. It's time consuming but cheaper and quicker than cutting parts and then realizing they don't fit.

kingcreaky
14-12-2012, 11:03 AM
Right, whilst spending all morning on the bearingstation website buying HTD timing pulleys and belts ive decided to scratch the idea of having one stepper for both ballscrews on the X axis powered by a long belt idea. Instead have one stepper per ballscrew..... This is mainly because I cant buy a belt 2.8meters long but also because it restricts the work area and also, lets face it, im bound to get my dude caught in it at some point... :D
So belts and pulleys ordered... I hope to god my calculations are right...
For a start point, ive decided to kick off with all the pulleys the same...

ive gone for 8 X HTD 5mm pitch,15mm belt width, 30 teeth. with a pilot bore
305M15PB - 5mm Pitch HTD Timing Pulley(Pilot Bore) (http://bearingstation.co.uk/products/Pulleys/HTD_Pulleys/HTD_Pulley_5mm/305M15PB)

so; recalling my school days; 30 teeth x 5mm pitch / pi (47mm diameter)
therefore, 2 pi (r) or 47mm x 3.14 (squared) = 147mm (lets call it 150)



PHG295-5M-15

PHG295-5M-15 5M HTD Timing Belt
1
4.46
4.46


PHG490-5M-15

PHG490-5M-15 5M HTD Timing Belt
2
6.30
12.60


PHG365-5M-15

PHG365-5M-15 5M HTD Timing Belt
1
4.90
4.90



As my wallet is taking an absolute kicking again, I may aswell buy some of this CY cable stuff... Im contious im gonna need about 12 meters to cover all three axis's so can somebody confirm if this is the stuff I want?
Bear in mind my controllers the higher power ones...
1.5mm 4 Core SY Protected Cable Flex (http://www.tlc-direct.co.uk/Products/MF1dot5slash4.html?source=adwords&kw=&gclid=CMGv8YjMmbQCFe7MtAodLjUA5g)

Jonathan
14-12-2012, 11:17 AM
The one you have linked to is SY, not CY. SY insn't shielded.

CY Cable - 4 Core 1.5mm2 (http://www.csecables.com/acatalog/CY-Cable-4-Core-1-5mm2.html)

kingcreaky
14-12-2012, 11:38 AM
what a sausage i am, thanks for the link

kingcreaky
18-12-2012, 10:09 AM
ali has arrived... everything I need now, short of CY cable and pulleys which are due this week.

made some legs (there are actually 6, but the dog ate one)
76567657

kingcreaky
20-12-2012, 10:37 PM
7708
Too many of you I am sure, the above is a simple plate. a Plate that can be knocked up in your engineering palaces in a matter of minutes, inbetween jobs, after a few beers.

For me however, this very plate has wasted more brain cycles, sweat, and most importantly self-doubt I cannot help but stand back an admire its sheer beauty. Its elegance...

Its literally taken me two nights... looking at it, measuring it, measuring again. Aligning the pillar drill then repeating the process again and again until I ultimately grew the nuts to trust my measurements, and simply start drilling.


To me, Its perfect. Bobby D! boys...

alex wight
20-12-2012, 10:48 PM
kingcreaky, before using the actual material, and possibly making an error. Try cutting it on mdf ir ply ect, to see if your correct then go ahead and cut the actual material, with the knowledge of knowing that your not going cock it up. Saves on grey hairs as well lol. Well done tho, now you can sleep till you have to do the same again lol.

WandrinAndy
20-12-2012, 11:50 PM
For me however, this very plate has wasted more brain cycles, sweat, and most importantly self-doubt I cannot help but stand back an admire its sheer beauty. Its elegance...

Its literally taken me two nights... looking at it, measuring it, measuring again. Aligning the pillar drill then repeating the process again and again until I ultimately grew the nuts to trust my measurements, and simply start drilling.

To me, Its perfect. Bobby D! boys...

I can totally relate to those kinds of feelings! In the absence of a good woman, it can even provide sweet dreams for a night or two!!

Sad but true.... Lol

kingcreaky
02-01-2013, 10:03 AM
happy new year all.
back at work today. what a blur the past week has been.

Didnt get as much done on this project as Id hoped. Spare time at christmas isnt what it used to be since we've had our first child. (18 months ago)

But did get some done.
7830783178327833

njhussey
02-01-2013, 10:10 AM
Looking good! You've done more than me over the period, I was away all over Christmas so nothings happened :( Still best pull my finger out as only got 2 weekends free this month to work on my one.

kingcreaky
06-01-2013, 08:10 PM
bit more done... just taking my time... checking and checking again before drilling. and LOADS of tapping (thinking about training misses to do it)

the gantry is now made; the bottom rail is only loosly bolted (need some shorter bolts)

its only sat on the slider plates, as to bolt it to them it needs to be assembled in place..

top rail just sat on top loosly
7888

JoeHarris
06-01-2013, 09:04 PM
Looking good! Got a stick welder for Christmas so just learning - seems I have one of biggest learning curves on here and being left painfully behind by you guys! Looking forward to seeing it live! Tapping for me is still fun - guess the novelty will quickly wear off?!

kingcreaky
07-01-2013, 10:21 AM
Sounds very rude referring to people by their chat handles, I apologise in advance.
Within JoeHarris's build log, JazzCNC points out that its not possible to get long belts in 15mm HTD flavour.(I also noticed this) His solution was to span the long length with a different flavour belt.
7895
(to be fair, probably the best solution). My plan was a little more un-thought out... My vision was to have dual steppers.. I had read in other build logs regarding the issue of missed steps but I hadnt really realised what this means... and disregarded it with a 'il worry about that later' attitude. The other reasoning behind this question is I ultimately would like to go down the spinning ballnut route ala Jonathons build. As Ive had the fear of god put through me regarding whip of the screws.

However ive just read your post on JoeHarris's build thread the following
**

No it doesn't go away but if the digital drive has a feature to monitor stall detection and send an alarm signal like the AM882 drive do then it's possible to use this to informthe control software to stop the machine and therefore the other motor before any damage is done.!! . . . . You'll still have lost steps and run out of position slightly but no damage is done.

**

I have bought these motor controllers
Cheap CNC! Wantai 4 PCS Stepper Motor Driver DQ860MA 80V 7.8A 256micro CNC Router Mill Cut Engraving Grind Foam Embroidery-in Motor Driver from Industry & Business on Aliexpress.com (http://www.aliexpress.com/item/Cheap-CNC-Wantai-4-PCS-Stepper-Motor-Driver-DQ860MA-80V-7-8A-256micro-CNC-Router-Mill/679049120.html)
(4) of them

Although I have a bob, it was one that come free with the above, I intend to buy another one when I have time to research the best one

Its mentioned above, the problem over missed steps is less significant if you have stall detection.. but I bet the above (cheap) drivers dont have this... ive looked but dont really understand what im looking at. What would you do?
1.)scrap idea of two steppers, and have an arrangement similar to that of the grand master above.. (im favouring)
2.)keep the dual motors (as I have all the gear to hand) where there is one stepper for each of the two screws (the gantry is quite heavy!) but I guess this may entail buying the motor controllers to replace the above?

I genuinly hope this isnt a stupid question.

Swarfing
07-01-2013, 11:29 AM
You can get open ended belt in any width up 30mm in HTD flavour. I used 5M HTD15 on my build of the reinforced polymer type. This works great but out of choice doing it again would stick with screws.

Jonathan
07-01-2013, 12:02 PM
2.)keep the dual motors (as I have all the gear to hand) where there is one stepper for each of the two screws (the gantry is quite heavy!) but I guess this may entail buying the motor controllers to replace the above?

I would keep the two steppers with the drivers you already have. I don't consider one stepper stalling and twisting the gantry to be an issue, since once you've set up the motors properly they will not stall. If they do stall then clearly having the stall detection feature is excellent, since it can prevent any damage, but the motors have no reason to stall so to me it's protecting against something that wont happen anyway. You also have more input power, since there are two motors, unless you use a reasonable size Nema 34 motor if just using one. With either system you always set the motors up such that they will never stall in normal operation, so you don't have to run it slower with two motors to play safe since if either configuration stalls it's set up wrong. Since you already have the drivers and motors(?) it doesn't really cost much to try it and plenty of people use either system. I don't have problems caused by having two motors.

Jazz will now vote for option 1.

Kerryfisher
07-01-2013, 11:43 PM
Coming along nicely KC, I'm researching building a plasma table, thanks for some good info along the way, good luck with the rest of the build. :thumsup:

JAZZCNC
08-01-2013, 12:00 AM
Jazz will now vote for option 1.

Won't go there regards stalling/racking has it's all been said.!! But there is more to this than just Stalling motors racking gantry's.?

The Main reason why I like it is Synchronization.?
My machine never loses position and the two ball-screws are synchronized exactly the same today has they were when first installed.
I don't have to worry that on long Jobs the machine will lose sync has the slaved steppers drop the odd step here or there running out of sync with each other slowly racking the gantry.

Don't have to worry that after 10-12 hours cutting I'm going to find that holes aren't where there supposed to be.!! Or the part isn't actually square after cutting profile out because the gantry slowly racked fraction of degree.!

The only way to ensure slaved steppers stay in sync is to either have very accurate Home switches or Home to hard stop and do it often. Certainly after every Job to be safe.
Even then if motors are tuned anywhere near close to the edge, esp regards Acceleration, they can easily lose steps without realising on jobs just a few hours long.
On Jobs that run non stop for 10-12 plus hours like litho-pains this could and has been for some slaved stepper users disastrous often resulting in not just in in-accurate work but stalls thru accumulative error over hours.!

Both work and won't argue that fact but I know which works best.!!

Jonathan
08-01-2013, 12:29 AM
has the slaved steppers drop the odd step here or there
[...]
On Jobs that run non stop for 10-12 plus hours like litho-pains this could and has been for some slaved stepper users disastrous often resulting in not just in in-accurate work but stalls thru accumulative error over hours.!

I have never seen any evidence of stepper motors on any of my machines loosing 'the odd step'. If it did they would be practically useless - it's either stall and loose lots of step or run perfectly.

If a motor does stall (which it wont if set properly) then it will only start moving when the step frequency has dropped to a low frequency, so it is possible to loose maybe a few steps (or tens of microsteps) if the motion is very small movements which constantly accelerate each motor, but that's still likely to damage the part whether it's one motor or two. Again, if the motors are tuned properly then, just like on Jazz's machine, you wont loose position so it doesn't matter if it's one motor or two. The only difference worth discussing is the input power considered with the whole system - if the basic calculations show that the motor and driver you can afford to use if just using one will perform better than the same calculation with two motors then go for it. If not it's illogical to use one.

wilfy
08-01-2013, 12:36 AM
from a neutral point of view with no experience just thinking about it logically. i'd want to reduce anything that could complicate things.. and to me that means running 1 motor even if that means on this axis you have to buy a big ass one to cope with it.

if your BoB/drivers are running 2 steppers on the same axis then you have 3 circuits there straight away that have room for error... the data comes along in 0's and 1's and all it takes is for a little interference on one driver circuit and one stepper didnt move as quick as the other.. bam your work is knackered and the machine is out of line....

now a single stepper has the same interference but this time the whole gantry didnt move.. only problem you have this time is take the wrecked piece of material shove where you like put a new piece down and start again as the machine is still straight


i'm not saying it wouldnt work.. and i have no doubt that yours works flawlessly jonathan, but my mind tells me to simplify to reduce the chance of error

Jonathan
08-01-2013, 01:25 AM
from a neutral point of view with no experience just thinking about it logically.
[...]
i'm not saying it wouldn't work.. and i have no doubt that yours works flawlessly jonathan, but my mind tells me to simplify to reduce the chance of error

That's the point though - by agreeing with that you're agreeing that your logical thinking earlier in the post is based on a false premise, therefore you may not be arriving at the correct conclusion even if the points you are valid. In other words, if my system did have a 'little interference' which caused one stepper to slightly loose position we wouldn't describe it as working flawlessly.

Either way, if you buy the right electrical parts either system can work flawlessly, so in the end it's just a case of working out which is the most economical.

JAZZCNC
08-01-2013, 02:15 AM
I have never seen any evidence of stepper motors on any of my machines loosing 'the odd step'. If it did they would be practically useless - it's either stall and loose lots of step or run perfectly.

Jonathan I've had to correct stuff you made because the fucking things weren't square or correct so don't give me that bollocks.!!

Also if your going to quote me then make sure you quote the whole fucking picture not just what you want to make fit.!!



Even then if motors are tuned anywhere near close to the edge, esp regards Acceleration, they can easily lose steps without realising on jobs just a few hours long.
On Jobs that run non stop for 10-12 plus hours like litho-pains this could and has been for some slaved stepper users disastrous often resulting in not just in in-accurate work but stalls thru accumulative error over hours.!

Both work and won't argue that fact but I know which works best.!!

kingcreaky
08-01-2013, 09:11 AM
Guys, I welcome all your comments, but really didnt mean to cause an argument. Lets just put the subject to bed.

Im in one of these junctions in the road now. Whatever I decide I dont want to alienate myself from advice from either of you.

I must say however, I think wilfy's comment summerises my present thought chain. and as I have genuinely lost, Yes Lost. one of my 3 steppers it was a case of buying two more for the X axis anyway. So simplifying the bits you cant bite (ie the electronics) and only having to buy one (bigger) stepper & a longer belt & some pulleys seems to me a favourable way forward.


Don't have to worry that after 10-12 hours cutting I'm going to find that holes aren't where there supposed to be.!! Or the part isn't actually square after cutting profile out because the gantry slowly racked fraction of degree.!

This machine has cost me an arm and a leg. Im worrying about lots of aspects of it all the time, so Simplifying this area I guess is one less thing to worry about.

On a seperate note; Im also worrying about how accurately I have mounted the gantry to the slide plates. I mean with my Set Square its bang on; when i slide it along the rails; the rails dont move out or in (however I havent yet bolted them down I think im looking to see if it gets tighter at one end) but if the gantry is not square like Jazz has mentioned above the work wont be square... I guess Il find out in time... Its this kind of think that is doing loops in my head everytime im down the workshop. I find myself standing there drinking coffee and smoking staring at it just thinking about (and questioning) the accuracy of my work.

JoeHarris
08-01-2013, 09:49 AM
I have not assembled a thing yet and this scares the hell out of me too, with buildings (what I'm used to on a day to day) the tolerances are like 5-10mm no 0.00 something! My thinking for what it's worth is that If you build enough adjustment into the design then you can shim things to perfection later...

Swarfing
08-01-2013, 10:36 AM
Guys i really think you are worrying about very little. I've used twin steppers and it was fine. I have belts running my machine with a single stepper on the X axis. It works great for the home machining i do......But! i have two ballscrews sat there ready to change to once i get round to it. If i can make a belt fit to control the screws from one motor then i will, if can't then i will just use two motors. Stick to your budgets up most and don't let bling go to your head. At the end of the day you are machinists now whether you like it or not, your nature will want you to change things later. There is no right or wrong way just preferences? I like both!
:beer:

Wobblycogs
08-01-2013, 11:21 AM
I'm glad to see that I'm not the only one worrying about how accurately the machine has been put together. I've just (mostly) finished one side of my frame so I've done a quick test fit. The bed rail and the guide rail are 0.1o out of parallel. Doesn't sound like much but that equates to just over 3mm over the total length according to my calculation :-(.

It's looking great though KC, keep the good work.

Jonathan
08-01-2013, 01:53 PM
Jonathan I've had to correct stuff you made because the **** things weren't square or correct so don't give me that ****


Yes you have once because the machine started off not square and I didn't realise. When it finished cutting I'm sure it was just as far out as when it started! If the machine had gradually lost 'squareness' then the cutter would have broken and the finish would have been terrible since they were so far out. Since then I have corrected the problem.
Also, I should add that the customer you're referring to didn't even tell me there was something wrong with the parts before asking you to fix it. If anyone has a problem with something I make, then I will do my best to fix it, but I can only do that if they tell me there is a problem. He also lied about where he'd sent the parts, but that didn't take much working out.




Even then if motors are tuned anywhere near close to the edge, esp regards Acceleration, they can easily lose steps without realising on jobs just a few hours long.


Easily solved - don't tune them anywhere near close to the edge. If you need to do that then you should have bought better motors or drivers.


There is an easy way to check how square the machine is once it is assembled and working:



Set the machine to drill 3 holes of the same diameter at the corners of a right angled triangle in some scrap, with one side parallel to X.
Push drills or bar the same diameter into the holes.
Measure using digital calliper the side lengths of the triangle by measuring the centre distance of the drills.
There are now various ways to find how off-square the machine is. You can draw the triangle (which will be scalene if the machine is not square) in a CAD program and measure the angle that should be 90 to find how far off it is. There are of course several ways to calculate this angle, or you could just use Pythagoras' theorem to see if the hypotenuse is longer or shorter than expected, then at least you know which way to compensate.
Correct for the error, then repeat until error is acceptable.
If two motors set the home switches appropriately if you have them, or you can put marks on thepulleys you can accurately align.


I got mine within +-0.01 using this method, but that was with a 600mm calliper. Still with a 150mm digital calliper you can get it very close. Also when measuring the hole spacing parallel to X or Y you should find they're within a few tens of micrometers:

79037904

There will be a slight error due to the lead error on C7 ballscrews, but as the images above show, at least in my case, this is very small - about 0.01mm in 600mm.

Swarfing
08-01-2013, 01:57 PM
Dog with bone?

kingcreaky
10-01-2013, 09:24 AM
Ok... so where do I buy a long belt from? the distance between screws is approx (i need to measure) 1.1 meters. So assuming im looking at 'Pitch Length' I need one approximately 2.2 metres?

maxium i can find is about 1.8 metres (1870mm)

im not bothered what 'pitch' it is etc, so long as its a timing belt. once ive found one il buy pulleys to suite, then bolt my existing stepper drive pulley to the ballscrew pulley (ala jazz)

7923

JAZZCNC
10-01-2013, 04:22 PM
If you go to any decent bearing and belt supplier you can have belts made to any length you want, thats what I did. Cost be about 15+vat if I remember correct.

Swarfing
10-01-2013, 07:14 PM
Why can't you use open belt? the gantry has to be fixed to one side of it any way?

Swarfing
10-01-2013, 07:24 PM
Sorry just re read and you want the belt to cross the screws. Give ERIKS in Swindon a call

Address: Unit 2/Ravenseft Pk/Cheney Manor, Swindon SN2 2QP
Phone:01793 533181

The do belts of any size within reason and i found them to be the cheapest at the time.

kingcreaky
10-01-2013, 11:01 PM
had one of them nights tonight... first off dropped the ballscrew and bent the end

7925

so, decided to fire up the big heavy green machine in the corner. I should perhaps at this point explain that the machine is jinxed. Every single time I use it, it ends up either hurting me, or my wallet

so spun it up.. the other end whipped round like a b*stard, I grabbed the ballscrew before it killed the dog and...

7929

thats the tidy version... (all those bearings went everywhere... for a moment, it was like a scene from home-alone)


so, after a few beers of contemplation, and a motivational chat with jonathon on skype I formulated a plan...
7926


7927
better. Not quite jonathon standard of engineering, I agree but much straighter.

So being an 'engineer' :D now. I decided to use this useful bit of kit too bore the holes in my pulleys

7928

decided to come up and finish my beer in the house before I broke anything else

7930 7931

GEOFFREY
10-01-2013, 11:44 PM
Better change your name to wobblycogs, oh no - too late!! have a better day tomorrow. G.

JAZZCNC
11-01-2013, 12:24 AM
better. Not quite jonathon standard of engineering, I agree but much straighter.

Oh I don't now looks about the same standard to me.!! . .:devilish:

wilfy
11-01-2013, 12:40 AM
so spun it up.. the other end whipped round like a b*stard, I grabbed the ballscrew before it killed the dog and...

http://www.mycncuk.com/forums/attachments/router-build-logs/7929d1357854968t-operation-cnc-20130110_192526.jpg (http://www.mycncuk.com/forums/attachments/router-build-logs/7929d1357854968-operation-cnc-20130110_192526.jpg)

thats the tidy version... (all those bearings went everywhere... for a moment, it was like a scene from home-alone)


i'm sorry but this has had me pretty much pissing myself everytime i read it... i just cant keep a straight face when i read over it and i think i've done so 5 times now..

i'm such a bad person.. and whats funny... i know damn right i'm gonna lose them balls one day

Swarfing
11-01-2013, 12:53 AM
Last time i bent my end and slung my balls out she gave me such a slap :hysterical:

JAZZCNC
11-01-2013, 12:56 AM
Last time i bent my end and slung my balls out she gave me such a slap :hysterical:

The trick is to get your balls in the right hole mate. . .:hopelessness:

kingcreaky
14-01-2013, 10:17 PM
Garden full of snow, baltic weather. But not in my workshop ;)
7948
properly cosy.


Right, quick update then.

Ordered replacement ballnut from Chai, aswell as four ballscrew blocks... Im also now waiting on more bandsaw blades.

7949

7950

not quite sure where im going to put the Y stepper... should of perservered with drawings.. but too impatient.




seperately, i have been given literally 2 tons of metal off-cuts. Its mainly 4mm and 5mm plate but some 3mm. all funny sizes but cut with machinery so all square. I think its galvanised?

anyway ive got far too much, and it was free so If anybody here needs any, come collect it. (leicester) The photo doesnt do how much ive got justice my estate car was on its arches with three loads. There is loads.

7951

JoeHarris
15-01-2013, 12:11 AM
I have been looking for some scrap metal to practice welding but I guess galv isn't ideal? Not sure? I begged some scrap from a local fabby but have nearly run out...if it's suitable for arc welding practice I'd gladly take some off your hands!!

JoeHarris
15-01-2013, 12:11 AM
Love the burner btw !

GEOFFREY
15-01-2013, 12:20 AM
Machine looks good too. G

kingcreaky
28-01-2013, 09:45 PM
ssssshhhhhhh******tttttttttt

so.... you guys always talk about planning planning planning... well ive made a big mistake

8062

the ballscrew nut housing, that are bought paid for and on their way from china... are 86mm wide

8063

WHAT a sausage.... I dont have that much space!!!

what am I going to do?

this is compounded by the fact ive ordered 4 of them, 2 for the x, 1 for y and 1 for z

Z dont fit

and guess what

8064

so, when you've finished laughing... and can think of some constructive ideas... let me know


Plucked up the courage to finish the Y though...

8065

r0bsk1
28-01-2013, 10:10 PM
If you've got the ballnut mounts from Chai they'll look nothing like the diagram he's sent you. They'll just be a steel block which you may be able to thin down the 86mm to less than 60mm. I dont have access to mine from Chai at the moment to get exact measurements but would say its deffo possible.

Jonathan
28-01-2013, 10:17 PM
You can probably just saw off the two flanges then drill and tap some holes in the bottom, then it'll be 52mm wide.

Here's some I made earlier...I've got one left if that's any use to you? I just copied the dimensions of the ones on eBay.

8066

GTJim
29-01-2013, 08:38 AM
KingCreaky,

I would try and mod the ones you have, but failing that this is a link to the mounts that I mentioned to you on Sunday.
Ball nut mount for 1605, 1610 ballscrew, free shipping to any country! | eBay (http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=300849450010)

Jim

kingcreaky
02-02-2013, 11:55 PM
so, after sitting about feeling sorry for myself.. Ive made atleast a temporary measure... not sure if its good enough for the stresses of milling ali... but will be good enough for now I hope.

fortunately ive got that old ballnut... the one I broke previously... useful...

so; heres the plan

8123

cut the circle out with the band saw (roughly). so it will go in my three jaw lathe chuck.

8124
bore the center out with lathe
8125

then get cutting and tapping...

8126

seems to work... (Jonathon... if you need any help with your 'engineering' give me a shout :yahoo:

martin54
03-02-2013, 01:00 AM
Why didn't you just make them in the first place if you have the gear to do it?? Sorry just being nosey lol

kingcreaky
03-02-2013, 08:44 AM
think its just lack of confidence martin. I think I mentioned before Ive had the lathe for a while but never really used it. Although your right now ive made one I do wonder why I bought the others... might sell them on or something (when they eventually turn up)

kingcreaky
03-02-2013, 07:46 PM
after Y comes?


8133813481358136

GTJim
04-02-2013, 01:02 AM
Looking really good and the ballless nut was just the ticket.

kingcreaky
04-02-2013, 06:26 PM
evening all... finding it hard to shut you lot up arent I... obviously your just lost for words ;D

anyway... get this.

So, I emailed chai, saying il have four of those ball nut housings to suite 1610 rails.

assuming he would send me the ones on his ebay shop er... these

8144

but .... he must of read my previous posts.... or something because I actually recieved these

8145

Im not having a moan, its not his fault. I didnt specify part numbers or whatever... these are actually the ones id prefer!.

anyway, so you may also notice the brand new ball-nut.....

how do I put that on the orphan screw? without dropping my balls everywhere?

Matt

Jonathan
04-02-2013, 06:36 PM
how do I put that on the orphan screw? without dropping my balls everywhere?

Just screw the nut on to the screw. Make sure you push the tube that's in the ballnut against the end of the ballscrew (so it's covering the end machining) as that will ensure the balls cannot drop out. Just do it slowly and carefully and you shouldn't have any problems.

martin54
04-02-2013, 07:31 PM
I doubt that Chai reads all the posts on every forum & even if he did would remember who had ordered what so I would think he has just sent you what he has got at the time.
That would annoy me, ok you didn't specify a part number but you did go by a picture in his webshop. I know that sellers have the right to substitute items if it's in their terms and conditions but if you had ordered these & had already done the work for this style to fit or were replacing existing units the new ones he has sent wouldn't fit.
I got caught out with some electronic components I bought from RS in a similar way, my fault I suppose for not reading the technical spec properly but not being a whizz with electronics I just went by the picture. RS were very quick to point that out to me so won't order from them again if I'm not 100% sure exactly what I need, what it looks like & how to use it properly lol.

GEOFFREY
04-02-2013, 07:42 PM
A tip I was given for removing and replacing the nut, but have not yet tried is that standard airline hose not (curly-wurly) is a really good fit (tight but flexible) and the nut can be wound on and off the screw quite safely. G.

wilfy
04-02-2013, 08:13 PM
I doubt that Chai reads all the posts on every forum & even if he did would remember who had ordered what so I would think he has just sent you what he has got at the time.
That would annoy me, ok you didn't specify a part number but you did go by a picture in his webshop. I know that sellers have the right to substitute items if it's in their terms and conditions but if you had ordered these & had already done the work for this style to fit or were replacing existing units the new ones he has sent wouldn't fit.
I got caught out with some electronic components I bought from RS in a similar way, my fault I suppose for not reading the technical spec properly but not being a whizz with electronics I just went by the picture. RS were very quick to point that out to me so won't order from them again if I'm not 100% sure exactly what I need, what it looks like & how to use it properly lol.

i can imagine what has happened here though


So, I emailed chai, saying il have four of those ball nut housings to suite 1610 rails.

assuming he would send me the ones on his ebay shop er... these

so creaky has noticed chai has ball nut housings in his ebay shop.. but then instead of going through the shop has contacted him direct and asked for 4 ball nut housings... yes maybe chai should have maybe said i have a few different types and asked which ones..

chai has likely just sent out the most popular ones. luckily though this worked out well any way

kingcreaky
05-02-2013, 11:50 AM
OK, Id like to have all the peaces together in order to get it moving at the weekend... or atleast try! assuming I can connect the X ballscrews and all the steppers this week I think it may be possible.

Ive also, for now decided to drive the X with dual steppers... rather than the single stepper long belt approach. Only because its easier (long story) Ultimately I may change my mind on this at a later date... but for the purpose of getting it initially going... 2 steppers it is...

So, I have already got
1 x 500w linear power supply from Zapp PS806-5 Linear power supply. (http://www.zappautomation.co.uk/en/power-supplies/438-ps806-5-linear-power-supply.html)
4 x DQ860MA 80v drives Stepper Motor Driver DQ860MA:Stepper Motor Driver DQ860MA wholesaler (http://www.wantmotor.com/ProductsView.asp?id=271&pid=82)

Im going to buy hopefully today in order to get delivered for weekend
1.5mm2 cy cable CY Cable - 4 Core 1.5mm2 (http://www.csecables.com/acatalog/CY-Cable-4-Core-1-5mm2.html)
2 x steppers for X axis 3.1nm (will these be powerful enough? it weighs a ton!) Nema23 Stepper Motor 3.1Nm (http://www.cnc4you.co.uk/index.php?route=product/product&path=83_84&product_id=65)
this breakout board? Im open to advice Breakout board CNC Stepper Motor 5 Axis Spindle Relay HG07 (http://www.cnc4you.co.uk/index.php?route=product/product&path=20_65&product_id=160)
1 x estop? Red Mushroom Emergency Stop push button switch NC 400V 6A (http://www.cnc4you.co.uk/index.php?route=product/product&path=86&product_id=143)

For now, until the machine is done and I can machine the face for the box all the electricery are in, im going to wire the steppers direct to the drivers rather than going via connector blocks. However I notice on some of the other builds fuse boxes are used... where about in the citcuit should I incorporate a fuse box (I assume after drivers and before steppers) What fuse box & how many fuses do I need etc?

Not sure if that breakout board is any good?

Can anybody recommend anything else im going to need.... or wish I had?

really appreciate your replies... reply even if you dont think you have anything to add... your probably going to know more about this subject that I and Id appreciate your thoughts....

ps - if anybody fancies a trip to leicester on sunday to be involved in a firing it up... all welcome pm me

martin54
05-02-2013, 12:10 PM
No expert as you know but just a couple of things, will you get away with running 2 motors from one outlet on the power supply which you will need to do as there are only 3 on the power supply you have. Maybe Jazz or someone will answer that.
What are you going to use to connect the breakout board to the drivers? I have actually used 4 core cy cable myself but not the 1.5mm which is to heavy, bought a couple of metres of 0.5mm for that. Same place you have listed so easy enough to buy a metre or two.
3.1Nm motors will be ok for this, they have been mentioned in a few of the threads for 2 motors on X axis.
Cable from pc to breakout board is about the only thing you havent mentioned. Not sure if the fuse boxes actually contain any fuses though or if they are just used to protect the strip connector that joins the short motor wires to the cy cable. Looks neater than a bit of chocolate block as well so may be the only reason.

ps. I live in Scotland so at least I should be reasonably safe on Sunday when Leicester goes into complete meltdown lol.

Jonathan
05-02-2013, 06:42 PM
The 500VA power supply is adequate. A little more would be nice, but it's not critical at this stage.


'2 x steppers for X axis 3.1nm (will these be powerful enough? it weighs a ton!)'

Plenty.


' Im open to advice Breakout board CNC Stepper Motor 5 Axis Spindle Relay HG07 (http://www.cnc4you.co.uk/index.php?route=product/product&path=20_65&product_id=160)
1 x estop? Red Mushroom Emergency Stop push button switch NC 400V 6A (http://www.cnc4you.co.uk/index.php?route=product/product&path=86&product_id=143)'

Cheaper options:
Emergency Stop Button - Twist Release - 1NC (http://www.tlc-direct.co.uk/Products/CGESB.html?source=froogle)
CNC4PC (http://www.cnc4pc.com/Store/osc/product_info.php?cPath=33&products_id=425)




where about in the citcuit should I incorporate a fuse box (I assume after drivers and before steppers)

Since interupping the current between the driver and motor can cause damage to the drivers, any fuses should be placed before. If you pop open the drivers you'll find they're already fused, but there's no harm in putting your own correctly rated fuse in if it makes you feel better.



Can anybody recommend anything else im going to need.... or wish I had? [...] if anybody fancies a trip to leicester

Er... me? PM on route.

wilfy
06-02-2013, 01:23 AM
ps. I live in Scotland so at least I should be reasonably safe on Sunday when Leicester goes into complete meltdown lol.

is that because you dont have any electric, so nothing to lose? :joker:

your progressing really well with this now dude and i really cant wait to see it finished, i just hope i get move mine a long as quick as you are and overcome any problems as easy as you have.. keep up the good work :D

martin54
06-02-2013, 02:06 AM
is that because you dont have any electric, so nothing to lose? :joker:

your progressing really well with this now dude and i really cant wait to see it finished, i just hope i get move mine a long as quick as you are and overcome any problems as easy as you have.. keep up the good work :D


Sorry to disappoint you wilfy but I do have an electric supply in my place, I ran a cable up from my parents house in Surrey a number of years ago :eagerness:

I'm actually looking forward to logging in on Sunday evening or Monday & seeing the video of it working, I must be really sad because I think it's great seeing the videos of the machines actually running having followed the build logs.

kingcreaky
06-02-2013, 09:31 AM
I hope not too disappoint!

So just about to place order for the breakout board on cnc4you, er this one

so, do I buy this? Breakout board CNC Stepper Motor 5 Axis Spindle Relay HG07 (http://www.cnc4you.co.uk/index.php?route=product/product&path=81&product_id=160)

or this ZP5A-INT (http://www.zappautomation.co.uk/en/breakout-boards/398-zp5a-int.html)

forget about the differences in price.... im more concerened about the stated input voltage of the first board... (7 to 55v) as opposed to the 5v USB power input the second board has

What are other people using... I know Jonathon has suggested a board.. but its in the states... and im inpatient.

D.C.
06-02-2013, 10:08 AM
Can anybody recommend anything else im going to need.... or wish I had?

Looking good mate, I'm currently in a mexican standoff over clearing the garage out. :(

You don't seem to have listed a spindle, bucket, water pump, hoses & clamps for water pump, limit switches, homing switches, cable for the switches, PC, software or any end mills?

PS on the pics of your z-axis at the rear you have a few cm sticking up at the top. If you stick a couple of bits of aly in there bolted to either side it will add rigidity.

8158

kingcreaky
06-02-2013, 10:47 AM
I'm currently in a mexican standoff over clearing the garage out. :(
:chuncky:


You don't seem to have listed a spindle, bucket, water pump, hoses & clamps for water pump, limit switches, homing switches, cable for the switches, PC, software or any end mills?

To start with, Im going to use a pencil!!!. I figure I cant cause any damage that way!. Il order one of these 2.2kw jobbies once Ive sold my wife. I also have a contact into coffee vending machines who can supply me lots of gear for this type of thing
hmmm.. limit switches etc Im going to get it working first, then get that bit sorted once I understand it a bit more
Got PC, Software (mach3, and linuxcnc on dual boot) and I work for the biggest industrial supply firm in the country. so tooling is no issue & cheap


re-bracing...
That is exactly my plan!. Im also putting some diag bracing on the frame... I was also thinking on the shoulders of the gantry... coming forward....
8159

JAZZCNC
06-02-2013, 01:12 PM
I hope not too disappoint!

So just about to place order for the breakout board on cnc4you, er this one

so, do I buy this? Breakout board CNC Stepper Motor 5 Axis Spindle Relay HG07 (http://www.cnc4you.co.uk/index.php?route=product/product&path=81&product_id=160)

or this ZP5A-INT (http://www.zappautomation.co.uk/en/breakout-boards/398-zp5a-int.html)

forget about the differences in price.... im more concerened about the stated input voltage of the first board... (7 to 55v) as opposed to the 5v USB power input the second board has

What are other people using... I know Jonathon has suggested a board.. but its in the states... and im inpatient.

Don't cut corners on the BOB for the sake of getting the machine running has you'll spend more time chasing problems than you will cutting.!!

Personally I think BOB's are Bastards who deserve to be hung.!!. . But that's down to back stabbing mate and cheating bitch Ex-wife. . LOl . . . But seriously the BOB is the worst culprit of causing problems and dropped steps etc than any other component. Cheap BOB's are just not worth the hassle.

Both those are just OK and nothing to get excited about the (7to55V) is handy because it gives you more options to power, I don't like 5Vusb powered stuff has the USB isn't reliable enough so in any case it would get an external 5V supply.

If you want the Cream of BOB's look here but you'll pay for it.!! PMDX.COM - Products for CNC and motion control applications (http://www.pmdx.com/PMDX-126)
The 122 is a good board and all PMDX stuff is high quality and they are very helpful with good warranty. PMDX.COM - Products for CNC and motion control applications (http://www.pmdx.com/PMDX-122)

If was me then I'd buy the 126 for many reasons but like I say not cheap but quality isn't and you get what you pay for.!!
Not be impatient it will just cost you money and frustrating hair pulling.!!

kingcreaky
06-02-2013, 01:28 PM
I wish I had seen this 10 minutes earlier. As ive just ordered the one off cnc4you now. sh!t

Anyway... this is an insignificant ballache compared to the fact ive just realised the garage pc (hp dc7700) doesnt have a Parallel port! F*ck

so.... I guess I need to buy a PCI card to be a parrelel port then? any recomendations do's donts etc?

Thanks for your replys by the way
Matt

kingcreaky
06-02-2013, 01:49 PM
scratch that, its got a parallel port

martin54
06-02-2013, 01:55 PM
Sure you could cancel the order for the board if required or look to sell it at a latter date if you decide to upgrade the board at a latter date. Think the board that Jazz has mentioned is the one that Michael has in his machine, as Dean had a lot to do with the build it wouldn't surprise me at all lol.

JAZZCNC
06-02-2013, 02:47 PM
Think the board that Jazz has mentioned is the one that Michael has in his machine, as Dean had a lot to do with the build it wouldn't surprise me at all lol.

Yes your right but had nothing to do with me.! . . (Well maybe a little) Michael mostly worked that out for himself and seen has it was on his way home sort of thing he called in and got one.!!

kingcreaky
07-02-2013, 06:49 PM
81768177
small update.

X Ballscrews on... and connected to gantry using chai's bearing blocks... (although run out of m6 cap bolts, so ordered some here tomorrow) - incidently, that means ive used 200

pulleys done on X, was very suprised at how effortless the gantry moves when turning pulleys. I was initially worried the steppers wouldnt have the balls but the gantry moves very easily.

I was even more suprised to see, if I just turn one ballscrew the drive goes down the ballscrew across the gantry through the other ballscrew and turns the other pulley.... thats got to mean ive done something right?

there is a bit of track... if you hold one pulley and turn the other... I think ultimately I will connect them both with one big belt.

seperately... Ive managed to scavenge a electrical inspection box from the darkest dungeons of where I work.... perfect for all the electricary and can be mounted to the machine.

8178

and.... cnc4you breakout board arrived today, along with the required extra steppers and a e-stop. CY cable also arrived from other supplier.

so, bit of luck may get a bit of ignition/fires on Sunday????? sooo excited.

kingcreaky
11-02-2013, 08:42 PM
need to share it with someone.. none of my mates appreciate the sheer brilliance

ITS WORKING!!!!!!

may of wasted potentially 200 notes on breakout boards that i didnt need... but il explain when im less excited.

GTJim
11-02-2013, 09:04 PM
That's sounding good. But let us in on your breakout board issues.

kingcreaky
11-02-2013, 09:58 PM
Ok... so all seems well... Y is working, Z is working. X however is causing me grief

as previously explained X has two steppers... I have set X to be one, and A to be the other

then in mach3 set A to be the slave of X

Ive wired the stepper drivers in 'active low' so

A-----------
PUL(+5V) --- 5v feed
PUL-(pul) --- PORT 9
DIR+(5V) --- 5V FEED
DIR-(DIR) -- PORT 8

X----------------
PUL(+5V) --- 5v feed
PUL-(pul) --- PORT 3
DIR+(5V) --- 5V FEED
DIR-(DIR) -- PORT 2

8201

both steppers turn correctly... however I need to reverse one... so it kinda goes in the opposite direction to the way its presently going?
doesnt matter which one...

make sense?

also, obviously im using a stepper controller for each stepper... cant I just use one controller for both?

JAZZCNC
11-02-2013, 10:16 PM
Just Change either of the DirLow active in Motor outputs and it will spin other way.

Yes you can control 2 motors with one drive but not good idea because of the way they work and sharing pulse's etc, just don't do it.!!
Also if your slaving motors you want away to control each motor for squaring the gantry and one drive won't allow that.

Danielroyal25
11-02-2013, 10:26 PM
Looking good! Is that a springer in one of the pics?

kingcreaky
11-02-2013, 10:31 PM
thanks jazz. do you mean just in the software... ie (changing tick to cross) or change the wiring aswell.... (or both)

dan - yep. thats Mr Cooper. 7 y/o my little mate.

JAZZCNC
11-02-2013, 10:37 PM
thanks jazz. do you mean just in the software... ie (changing tick to cross) or change the wiring aswell.... (or both)

Well really it's better to change the wires because of the way the rising pulse works but you can just change it in software and it will work fine. If you have any funny happenings like missing steps on that motor then change the wiring but 99% of time with modern drives it will be fine.

Noticed the screen shot shows B axis active and A axis not but you say your slaving A axis was that a Typo.?

kingcreaky
11-02-2013, 10:48 PM
thanks jazz.. yes a type B is the slave

Ive done that... and it works fine now in one direction,.... but when I change direction one axis goes in reverse and tother carries on going forward

Jonathan
11-02-2013, 10:57 PM
Well really it's better to change the wires because of the way the rising pulse works but you can just change it in software and it will work fine. If you have any funny happenings like missing steps on that motor then change the wiring but 99% of time with modern drives it will be fine.

I don't see how inverting the direction in software could make the system and less reliable than swapping either phase wires round to reverse the motor. They have the same effect.

JAZZCNC
11-02-2013, 10:58 PM
thanks jazz.. yes a type B is the slave

Ive done that... and it works fine now in one direction,.... but when I change direction one axis goes in reverse and tother carries on going forward

Not making sense now.? . . . When you reverse which Axis carries on forward.?

Why did you need one motor spinning opposite to other anyway if your slaving.?

What BOB are you using.?

JAZZCNC
11-02-2013, 11:01 PM
I don't see how inverting the direction in software could make the system and less reliable than swapping either phase wires round to reverse the motor. They have the same effect.

Well go Google it because I'm Not in mood for arguing with you tonight Numb nuts.!

kingcreaky
11-02-2013, 11:24 PM
lol. sorry jazz.

thanks for the advice... you were right. I was being stupid. :beer:

D.C.
11-02-2013, 11:47 PM
Well go Google it because I'm Not in mood for arguing with you tonight Numb nuts.!

Got to agree with Jon, sorry jazz! Computers are pretty good at assigning values to variables and then reading them again, they do rather a lot of that sort of thing millions of times a second... If your software can't handle that simple task you need some new programmers.

JAZZCNC
11-02-2013, 11:47 PM
lol. sorry jazz.

thanks for the advice... you were right. I was being stupid. :beer:

No need to apologise to me.! . . . Wasn't having a go at you or meaning not in mood for answering your questions just not going to argue for the sake of it when it wouldn't help anyone and turn the thread into another one of is " Up man ship" trips.!

So are you working has expected or would like now.?

GEOFFREY
11-02-2013, 11:54 PM
Congratulations, looks like you are away now. Lets see some bits you make in the showcase. G.

wilfy
12-02-2013, 12:46 AM
i demand a video now... :beguiled:

in all seriousness i'm impressed at the speed you have moved with this and i really hope you stick around and show us all what your machine is capable of, it's very inspiring to see someones hard work actually doing something. well done fella

kingcreaky
12-02-2013, 02:06 PM
admitedly lazy of me but im planning on ordered one of the 2.2kw spindles today... theres some on ebay for 250...

can anybody recommend some cutters to get me started... il just be prancing around with mdf for a while...

it says
Collet: ER20(4mm,6mm,8mm,12mm,12.7mm) Runout off: less than 0.005mm
any help appreciated...

JAZZCNC
12-02-2013, 04:50 PM
Try a pencil first much cheaper. . . Lol

What your planning on cutting will determine which cutters and size you'll want to use.
If Aluminium/plastics then 6mm is a good all round size and single or twin flute are best, 3 flutes at the most. Carbide will cost more than HSS but last longer and allow higher feeds and DOC. HSS are good for learning has they are cheaper. I use Cutwel Limited | Cutting Tools & Machine Tool Accessories (http://www.cutweltools.co.uk) for my metal/plastics tooling.

If cutting MDF then ONLY use carbide has MDF dulls HSS in no time. Size will depend on what your doing and often wood cutters come in imperial shank sizes so 1/4" 3/8" 1/2" are common shanks also 8mm. Actual cutter sizes can be quit large with wood bits and 1/2" shanks can yield 50-60mm cutter widths.
I use Wealden Tool Company (http://www.wealdentool.com) for wood/mdf bits.

Most spindles only come with 1 collet often 6mm so I'd Buy a set of Collets when you buy spindle and you'll be sorted for every shank size upto 13mm, Only need one set for both imperial and metric shanks.

martin54
12-02-2013, 07:05 PM
The spindle i bought came with different sized collets as you have listed in your post but if you intend using smaller bits you will need to buy smaller collets. 4mm being the smallest it comes with.

Anyway stop changing the subject, lets here all about the breakout boards lol

m_c
12-02-2013, 07:57 PM
Got to agree with Jon, sorry jazz! Computers are pretty good at assigning values to variables and then reading them again, they do rather a lot of that sort of thing millions of times a second... If your software can't handle that simple task you need some new programmers.


Computers are very good at dealing with numbers, but having two matched hardware outputs is better.
By using the software to mirror signals, you can end up with slight timing discrepencies, however most of the time it won't cause any issues.

kingcreaky
13-02-2013, 10:46 PM
Evening Gents...

Right then... got a video for you at long last...

Past few days have been spent messing around with Mach3... and this evening ive been googling G-code... and even wrote my first bit

this is the 'house'
>>dont properly understand this bit copied it off internet
g0 g21 g90 g50 g80 f100
g0 z0 g0 x0 y0 set
m98 p1 l10
g0 x0
m30
%
o1

>> this is the bit i wrote!
z-30 >> drop the z down to where the pencil touches
g1 x0 y0 f3500
g1 x-200
g1 y-200
g1 x0
g1 y0
g1 y-200 x-200 f3200
g1 y0
g1 y-200 x0
g1 y0
g1 x100 y-100
g1 x0 y-200
g1 y0

and the circle... Really dont undestand this... found a wizard page on the net that made it...

G21 (mm)
G0
F3200.00
X0 Y0 Z0
Z-30
G1 X-99.5000Y0.0000
G2 X-99.5000Y0.0000 i99.5000j0
G0Z0.1000 (Retract)



http://www.youtube.com/watch?v=WsAYwO3VJng&feature=youtube_gdata

thanks to Jazz and Jonathon for their help and patience with my repeated stupid questions

hope this inspires others.... (WILFY!!!!) to get started!!

Jonathan
13-02-2013, 10:57 PM
Now draw it without overlapping any lines or retracting the pencil ;)

It sounds like the acceleration on your machine is set quite low, what value is it currently? You should be able to get at least 1m/s^2 comfortably.

In mach3 there is a list linked to from the main screen which explains what each G-code does, so it shouldn't be difficult to work out what the initial commands do and how the arc command has been used to construct a circle.

wilfy
13-02-2013, 11:14 PM
awesome, love your ghetto pencil rig up as well.. i never realised the steppers made so much noise though, is this due to the spindle being much louder hence why you never hear them?

JAZZCNC
13-02-2013, 11:18 PM
Little tip with G-code. G0 and G1, G2,G3 are whats called modal commands so you don't need to repeat the G0 or G1 after the first instance IE:
G1 x10 y10 f200
G1 y30 z-12
G1 x50 y20

could be written.

G1 x10 y10 F200
y30 z-12
x50 y20
The G1 linear command will stay in affect untill it's cancelled by either another Modal command Like G0, G2,G3 or a cycle command like G83 drill cycle.
Same goes for the F# this feed rate will stay in affect until changed by another F#

GEOFFREY
13-02-2013, 11:59 PM
Its the stupid ones that don't ask questions. Video looks good, now lets see some cutting. I'm sure Wilfy is dead keen to get going now - and many others. G.

wilfy
14-02-2013, 12:08 AM
Its the stupid ones that don't ask questions. Video looks good, now lets see some cutting. I'm sure Wilfy is dead keen to get going now - and many others. G.

i am, i'm just a bit distracted with other stuff at the minute and i dont wanna start my machine until i know i can go at it full throttle. i have the cash to go buy the steel whenever but that would be it, so i could have my machine free rolling on its rails then i'd have to stick it to one side till i could afford the steppers and drivers/psu.

so for now i'll keep pushing everyone else who is building to post videos up to keep inspiring me :stupid:

D.C.
14-02-2013, 01:36 AM
Computers are very good at dealing with numbers, but having two matched hardware outputs is better.
By using the software to mirror signals, you can end up with slight timing discrepencies, however most of the time it won't cause any issues.

Could you explain this in very, very great and technical detail? I really don't get it. I'm utterly clueless about CNC machines but me and computers go way back and I'm a bit confused about this concept.

There is no such thing as 'hardware' in this context because the pin assignment of a parallel port is always determined by 'software'. If you attach a printer to the parallel port the computer will use the pins differently compared to how the computer uses them when a scanner or for example a cnc machine uses them. 'Hardware' here is a meaningless concept, devices come, devices go, the signals that are sent down the wire are determined by software just as different ships come and go from a harbor and the ability of a ship to dock with a port is not dependent on the cargo that a ship carries or the people on board a ship, if you can physically fit into the harbour and attach one or more cables to one or more bollards you are officially 'docked' in 'port'. This analogy is why a parallel 'port' is called a 'port'.

Perhaps a different analogy is in order:

Scenario 1 - You are sitting in a room, I walk in to the room with two people that you do not know. I point to the first person and say this is Bob, I point to the second person and say this Fred, they will be working for you. You go away and spend the rest of your life calling Bob 'Bob' and Fred 'Fred'. All is good with the universe.

Scenario 2 - You are sitting in a room, I walk in to the room with two people that you do not know. I point to the first person and say this is Fred, I point to the second person and say this is Bob, they will be working for you. You go nuts and kill everyone in the building, shortly after the universe implodes. This is because everyone knows that it is an irrevocable law of phyiscs that people called Bob must always be introduced before people called Fred.

If you think this is getting a bit ridiculous now you are right...

wilfy
14-02-2013, 01:53 AM
if you ever struggle to think of electronics and need to use examples always use water... it's far easier.

i.e. example 1 you have 1 hose pipe(outgoing signal) with a splitter in the end to make 2 outlets (2xsteppers)... water reaches the splitter and splits equally between the 2(both steppers get the same signal)

example 2 you have 2 hose pipes connected straight to 2 outlets and the flow of these is restricted by a computer, something goes wrong with the first outlet and the flow is slightly restricted at the wrong time compared to outlet 2.. you now have one pipe pouring more water than the other (one stepper moving out of sync to the other.

it's just limiting the possibilities of things going wrong. i understand what jazz is on about and i "go way back" with computers

D.C.
14-02-2013, 03:41 AM
if you ever struggle to think of electronics and need to use examples always use water... it's far easier.

i.e. example 1 you have 1 hose pipe(outgoing signal) with a splitter in the end to make 2 outlets (2xsteppers)... water reaches the splitter and splits equally between the 2(both steppers get the same signal)

example 2 you have 2 hose pipes connected straight to 2 outlets and the flow of these is restricted by a computer, something goes wrong with the first outlet and the flow is slightly restricted at the wrong time compared to outlet 2.. you now have one pipe pouring more water than the other (one stepper moving out of sync to the other.

it's just limiting the possibilities of things going wrong. i understand what jazz is on about and i "go way back" with computers

except this is a false analogy.

If you 'go way back' with computers and understand what you are talking about perhaps you can explain what is wrong with what either I or Jon said in this very specific instance.

Does a piece of software running on a computer have magical pixie hero men inside of it that create a 'magical physical hardware' perfect connection between the software and the cnc machine or does a computer use a piece of software (often called a driver) to decide in 'software' which signals to send to which lumps of metal?

If 'hardware' is somehow so much reliable than 'software' and desirable perhaps you could explain why mission critical systems use ECC ram, or why we need transactionable databases or why TCP has to sit on top of IP?

kingcreaky
14-02-2013, 10:21 AM
if you search for 2.2kw spindle on ebay... you will notice they are all portsmouth based suppliers. It appears there are multiple suppliers but Im sure its just one place selling them.

Over the course of the past 4 days, I have messages 7 individual suppliers. asking them to confirm they have stock, are they shipping from the uk I have recieved NO responses.

Most of them are 'make an offer' so ive tried making an offer say a tenner below the asking price, again NO responses.

You will notice that essentially the price is 252, some of them are a straght 252, some of them are 162.00 with 90 postage and all the variations under the sun. However I just cant get a response from them so im hardly willing to send them money.

Which leaves me with cnc4you.. who are offering a bargain price of 369 however they are uk based and offering a direct warranty

or Chai has quoted me in his "best price" kinda way 310 plus 60 postage

are there any other options? ive googled 2.2kw spindle with not much luck... thought id check with you lot before I order

Matt

martin54
14-02-2013, 01:46 PM
Matt, I suspect your right about the one seller using multiple ebay names, has been mentioned before either on this forum or another. Lack of a reply may be down to them being away at the moment. Apparently it's the Chinese Spring festival at the moment, I was looking for a cooling pump for a 2.2kw spindle & tried searching ebay for the one Robin suggested. Found a seller on the uk site (Chinese) who had a message saying he was closed from 7th to 17th feb for this festival.

D.C.
14-02-2013, 03:01 PM
Sorry about the thread hijack and congrats on the progress btw.

martin is right, it is chinese new year which these days is apparenty the largest migration event in human history, hundreds of millions people moving from the cities back to their home villages to spend two weeks with the family. Give them a couple of weeks and it they will be back to business as usual.

Edit: On the plus side if you can find guys still trading as normal delivery times seem very impressive, two orders I placed for electronics stuff with bog standard freebie China post arrived in 4 days and 6 days. (Real days not working days)

m_c
14-02-2013, 07:17 PM
D.C. in theory, everything should work, but in practice, things may not work quite right. It can be things like marginally different speeds between a pin switching high and low, which are then exaggerated by drives that respond slight differently to high/low inputs and/or slight lag due to the different switching speeds. However with modern drives, it's pretty much a non-issue, but why take the chance?

Personally, given the choice of doing something in hardware or software, I'd personally do it in hardware every time, as it helps eliminate potential issues.

Jonathan
14-02-2013, 07:29 PM
D.C. in theory, everything should work, but in practice, things may not work quite right.

If it works in theory but not in practice, that just means your theory wasn't good enough.


It can be things like marginally different speeds between a pin switching high and low, which are then exaggerated by drives that respond slight differently to high/low inputs and/or slight lag due to the different switching speeds. However with modern drives, it's pretty much a non-issue, but why take the chance?

Personally, given the choice of doing something in hardware or software, I'd personally do it in hardware every time, as it helps eliminate potential issues.

Again, the answer is vague so I'll repeat what D.C. asked - what specifically is the problem? The timing delays you're talking about are completely negligible, so there is no potential issue to eliminate. Originally the question was if you should set the motor directions in software, or one of the motor phases round to invert the direction. There will not be any tangible difference between the two, unless the software is pathetic.

m_c
14-02-2013, 08:04 PM
Jonathon, go and search the Mach Yahoo group for Art's posts about the intracies of parallel port timing, because I'm beginning to understand why Jazz gets so pissed of with you.

D.C.
14-02-2013, 08:04 PM
Interesting, I would trust 'software' over 'hardware' everytime. I tend to see hardware as crap and dumb , you send a bunch of electrons down the wire and pray they get to their destination (why do we need shielded cable again?) when you add a bit of intelligence into the equation you can account for and correct errors, hence why people looking for better precision use closed loop steppers and absolute positioning systems to catch and correct the all the errors produced by the hardware.

Without the ability to fix all the hardware issues using cleverness the internet would be stuck in the telegraph age. :(

m_c
14-02-2013, 08:08 PM
DC, I'd rather trust hardware, as hardware being dumb, should always do the same thing.
It's a bit like do you swap a motor phase on a VFD, or do you just change the setting in the VFD to change normal motor direction?
Both should work...

kingcreaky
01-03-2013, 01:11 PM
so, its all now going. Im working out bits as I go along slowly but surely.

So Im milling my mdf spoil board flat so, the machine is going
Y0,
Y800
X2
Y0
X4
Y800
etc etc

side to side stepping back 2 on every pass

now.. if I press STOP in mach3... the machine abruptly comes to a stop. I press goto Z and I suspect the Y has slipped a little? Its more noticeable if I start the program again... the pocket its milling out of my spoilboard seems to have moved over slightly?

does this make sense to anybody?

matt

kingcreaky
01-03-2013, 02:06 PM
are you pressing the stop button you numpty instead of the pause?

kingcreaky
01-03-2013, 02:06 PM
yes. what a sausage

JAZZCNC
01-03-2013, 05:55 PM
Always press FEED HOLD other wise your 99% sure to lose position if travelling at any reasonable feed rate.

Just be aware that FEED HOLD doesn't always stop instantly and will depend on the code and the LOOK AHEAD setting in Mach to how long it takes.

CraftyGeek
14-08-2013, 07:14 PM
Creaky - i'm researching gantry's at the moment while trying to design mine...could you possibly post a picture showing how you mounted the Y-axis motor to the back of your gantry?