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trounce
05-09-2011, 08:01 PM
Hey guys,
I want to start my own DIY build so I've been reading the forums for quite sometime along with watching lots of videos on youtube but I'm still really pretty clueless about a lot of the terms and jargon that's being used.
Is there anywhere I can find a "idiots guide" to building your own cnc machine? because it seems the more I research the more I find different systems that all seem to do the same job which ends up confusing me even more :confused:

The machine I need will be mainly used for cutting 8' x 4' sheets of 18mm MDF using a 8mm bit and maybe thin perpsex but nothing more than that.
I don't know how realstic my budget of 1000 is but that's really all I have to play with.

Any advice or where I should start would be greatly appreciated.
Cheers in advance.

Jonathan
05-09-2011, 08:24 PM
Is there anything specific you would like clarifying?

1000 sounds just about possible for that size machine.

I would start by finding pictures of similar size machines and pick and choose from them. Please post a drawing before you buy anything...

luke11cnc
05-09-2011, 09:07 PM
I agree don't buy a thing until you've got a good idea what you want.

Because as I found out it's more than likely wrong,to small or to weak

don't cut corners on the frame and ask ask ask away

James & Luke

Jonathan
05-09-2011, 09:30 PM
is this what you had in mind jon http://www.youtube.com/watch?v=iaRc8c4Qwn4 for a grand i,d like to see it done.

Nah, can do better than that. Give me a grand and I'll prove it :lol: You and JohnS reckon I'll be a millionaire 'soon enough' so I'm sure you'd get the money back!

The critical point is '18mm mdf ... nothing more than that', so the machine does not need to be massively rigid and a 50mm Z-axis should be fine. If you're sticking to that budget then start with a simple 8x4 rectangular steel frame mounted on a strong table or the floor which shouldn't cost much. Use linear bearings from ebay (linearmotionbearings2008), or to get it cheaper explore one of the other methods.

No mention of required feedrate, so I'm sure 3nm motors would be plenty... I reckon it's possible though in my opinion you'd be much better off in the long run spending more to start with.



Because as I found out it's more than likely wrong,to small or to weak
don't cut corners on the frame and ask ask ask away


By all means cut corners, as long as they're square. :naughty: Not going to be much of a frame without corners. Mine was far too big and too weak to start with.

trounce
06-09-2011, 06:01 PM
Thanks Guys, been doing more research up until the small hours and starting to get a better undertsanding.
Whats the general rule for frame size vs the actual cutting area? I'm limited for space so I'm hoping that 10' x 5.5 will be enough for 8' x 4. I only ask because I was looking at the linear bearings on ebay and the nearest size I'll be needing are 2750mm which is a fair bit past the actual cutting size.

luke11cnc
06-09-2011, 06:14 PM
You can have them cut to size
if you email him and give the length you want he will give you a price

James

JAZZCNC
07-09-2011, 12:27 AM
Hey guys,
The machine I need will be mainly used for cutting 8' x 4' sheets of 18mm MDF using a 8mm bit and maybe thin perpsex but nothing more than that.
I don't know how realstic my budget of 1000 is but that's really all I have to play with.

Any advice or where I should start would be greatly appreciated.
Cheers in advance.

Hi,

First what tools do you have access too and what skill level or experience do you have working with metal.? . . . IE: Welding etc.

Building what you want is just about do-able for a grand but will need you to have the right tools and skill level, OR friends that do.! . . Along with some savy purchasing. Plus you'll need a rock solid design that you know will suit your needs along with good plan of attack because you'll have no room for error if your wanting to do it for around 1000.

Steel box frame and Rack & pinion on the X&Y Axis with ballscrew or lead screw on the Z axis is the route I would take for a Really strong accurate machine of this size.
Belt drive would also be an option which is relatively cheap and very accurate and lends it's self well to machine this size.

Best advice DONT BUY A THING untill your 110% sure the design you have choosen will do what you need, then have it checked out by others for reassurance.
Then and only then start buying materials needed and even then dont buy to far in front because plans have a nasty habit of changing on the fly very easlily rendering some parts or materials unsuitable purpose. . . . . It's like eating an elephant.? . . . best done in small bytes.
Like any good constructuion it all starts with good foundations(the frame), weak foundations will tranfer into a weak machine. . . . Equally poor materials will render poor results.
Also like any other construction the methods and skill levels of the builder will have a massive affect on the end result. I've seen some very good strong designs built with very high quality components that have been completely FUBARD due to poor skill levels built with caveman tools.
Equaly I've seen fantastic machines built with basic tools and cheap components when mixed with good skill and reasonabe tools, mix with a good dose of imagination and the results can even blow away some big buck machines.

Don't rush and ASK Q's then some more Q's and then more Q's not matter how dumb you feel or think they sound, keep asking untill you fully understand and are comfortable to go.

trounce
07-09-2011, 11:34 AM
Hi,

First what tools do you have access too and what skill level or experience do you have working with metal.? . . . IE: Welding etc.

Building what you want is just about do-able for a grand but will need you to have the right tools and skill level, OR friends that do.! . . Along with some savy purchasing. Plus you'll need a rock solid design that you know will suit your needs along with good plan of attack because you'll have no room for error if your wanting to do it for around 1000.

Steel box frame and Rack & pinion on the X&Y Axis with ballscrew or lead screw on the Z axis is the route I would take for a Really strong accurate machine of this size.
Belt drive would also be an option which is relatively cheap and very accurate and lends it's self well to machine this size.

Best advice DONT BUY A THING untill your 110% sure the design you have choosen will do what you need, then have it checked out by others for reassurance.
Then and only then start buying materials needed and even then dont buy to far in front because plans have a nasty habit of changing on the fly very easlily rendering some parts or materials unsuitable purpose. . . . . It's like eating an elephant.? . . . best done in small bytes.
Like any good constructuion it all starts with good foundations(the frame), weak foundations will tranfer into a weak machine. . . . Equally poor materials will render poor results.
Also like any other construction the methods and skill levels of the builder will have a massive affect on the end result. I've seen some very good strong designs built with very high quality components that have been completely FUBARD due to poor skill levels built with caveman tools.
Equaly I've seen fantastic machines built with basic tools and cheap components when mixed with good skill and reasonabe tools, mix with a good dose of imagination and the results can even blow away some big buck machines.

Don't rush and ASK Q's then some more Q's and then more Q's not matter how dumb you feel or think they sound, keep asking untill you fully understand and are comfortable to go.

Thanks Jazz, that looks like a lot of great advice.
When it comes my tools I don't really have that much in terms of metal working. I want this machine to cut out cabinet pieces for my arcade machines so I guess most of my tools are woodworking.
I have experience with welding so that's not a problem, sometimes it doesn't end up looking that pretty but then I have my grinder to clean it up :tup:

I have a 110 amp Mig welder, angle grinder, bench grinder and bench drill along with the usual hand tools, drill, jigsaw, sanders, dremel etc.

I saw a very nice belt driven home build on youtube and I'm very tempted to use this on the X & Y axis, Im presuming that due to the size of my machine I would need two motors on the Y axis as apposed to just one on the machine I saw as it was much smaller?

m.marino
07-09-2011, 03:05 PM
Yep a very good post and one which is very wise to listen to. I am right now designing machine number two (first was a kit) and wishing I had built from the start. Though I have learned a lot and the machine is right now cutting parts to be sold which is paying for itself slowly.

Ask tins of questions. Get access to a CAD program (I would suggest ViaCAD as very affordable for the quality/support you get) or a lot of sketch paper and draw every detail out. Work it out then post it here and ask more questions. Trust me there is more then enough folks here who A) really know what they are talking about and B) really will try to help you get a good build for the money you put into it. Just remember that building slowly and with totally ridge mentality to precision will pay off for a very long time.

Best of luck and keep going.

Michael.

luke11cnc
07-09-2011, 03:29 PM
Michael Viacad ??

is it Viacad punch I need??

what version are you using

how much did you pay for it??

James

trounce
07-09-2011, 04:49 PM
Edit: double posted in error

m.marino
07-09-2011, 05:27 PM
James,

I am using ViaCAD 2D/3Dv8 and bought it during the pre release ($69). You can get it now for $99 on their site and might be able to get a discount of 15% (I don't know if it is still running). It is a really useful program based on the ACIS modelling core (Same core as SolidWorks). No it is not at that level as it is also not at that price, but for a good MCAD/ACAD program that will get a lot done with excellent forum and support via that forum it is very hard to beat. Comes with videos and pdf user manual (that needs updating in places and they do know and are working on it). The drawings you see my putting up in the forums now on my build are done by ViaCAD. That plus a good CAM and your set on that side of things (CamBam, Aspire, and a few others come to mind). Trust me you don't want to cut corners on software or you end up editing a lot (don't ask how I know).

As to the OP good luck and keep going it takes time and doing it right is worth the time taken. Trust me I know that one the hard way.

Michael

JAZZCNC
07-09-2011, 06:37 PM
Hi Neil,

Those tools are more than enough in the right hands.
Regards the box 50x50 3mm wall is Ideal and cost affective.

The size of machine you want I started to design for a guy a year or so ago and to do pritty much the same panel work. The budget was tight on this as well but didn't want to build weak.
It was decided steel frame and R&P was the best way to go. Often most designs requires driving the X (or long) axis from both sides and this means extra expense, 2 motors, 2 drives,larger power supply etc.
So I started designing so I could build it with just 1 larger motor on the long Axis 3:1 ratio giving roughly a 25mm pitch thou can be changed with differant sized pulleys and/or pinion.! . . . The pics below are as far as I got. (As folks are probably gathering by now I like my pics.!!. . . They tell a thousand words. :tup:)

It's just a rough layout design and still needs plenty more work but the frame etc are all to scale thou a little extra strengthening to the bed and some bracing are still required. The dimensions are 3mtr x 1.5 which is more than enough for 8x4 sheets.
It never got built due to the guy being made redundent and it's currently on hold untill another day, hence I stopped designing.
If you want to know more drop me a PM and I'll give ya my number.

Also digging this out got me thinking how much the steel would be for this frame and If it could be built for 1000.???
So I rung my supplier and got a price for 50x50x3 7.5mtr lengths of 25+Vat . . . I've worked out 6 lengths lengths of box section should be more than enough. . . so 150 will build you the base frame and gantry.
Commercial Rack is roughly 30 for 2mtr lengths so 120 for X&Y axis, pinions 8 x 3 shaft say roughly 20, Bearings and pulleys approx 50 so R&P for X&Y Axis approx 220-50.

Throw in roughly another 300 for linear rails and you still havent got Z axis or motors, drives, PSU etc . . . so what I'm saying is on reflection then 1500 is more than likely your finished price. thou for 1500 you'll have a cracking machine.

luke11cnc
07-09-2011, 07:22 PM
if your using 25 mm supported rails you will need 60mm to mount them on don't buy the bearings for this size as I will give YES give you 4 as I have extra

James

trounce
07-09-2011, 10:49 PM
Hi Neil,

Those tools are more than enough in the right hands.
Regards the box 50x50 3mm wall is Ideal and cost affective.

The size of machine you want I started to design for a guy a year or so ago and to do pritty much the same panel work. The budget was tight on this as well but didn't want to build weak.
It was decided steel frame and R&P was the best way to go. Often most designs requires driving the X (or long) axis from both sides and this means extra expense, 2 motors, 2 drives,larger power supply etc.
So I started designing so I could build it with just 1 larger motor on the long Axis 3:1 ratio giving roughly a 25mm pitch thou can be changed with differant sized pulleys and/or pinion.! . . . The pics below are as far as I got. (As folks are probably gathering by now I like my pics.!!. . . They tell a thousand words. :tup:)

It's just a rough layout design and still needs plenty more work but the frame etc are all to scale thou a little extra strengthening to the bed and some bracing are still required. The dimensions are 3mtr x 1.5 which is more than enough for 8x4 sheets.
It never got built due to the guy being made redundent and it's currently on hold untill another day, hence I stopped designing.
If you want to know more drop me a PM and I'll give ya my number.

Also digging this out got me thinking how much the steel would be for this frame and If it could be built for 1000.???
So I rung my supplier and got a price for 50x50x3 7.5mtr lengths of 25+Vat . . . I've worked out 6 lengths lengths of box section should be more than enough. . . so 150 will build you the base frame and gantry.
Commercial Rack is roughly 30 for 2mtr lengths so 120 for X&Y axis, pinions 8 x 3 shaft say roughly 20, Bearings and pulleys approx 50 so R&P for X&Y Axis approx 220-50.

Throw in roughly another 300 for linear rails and you still havent got Z axis or motors, drives, PSU etc . . . so what I'm saying is on reflection then 1500 is more than likely your finished price. thou for 1500 you'll have a cracking machine.

If you don't mind me asking, where can I find the rack at that price? I've been googling away and only managed to find some on ebay for 56 a metre, I must be looking for the wrong stuff :cry:

JAZZCNC
07-09-2011, 10:53 PM
WMH transmission . . . Here you go. http://www.wmh-trans.co.uk/Products/1_MODULE_SPUR_RACK_MATERIAL_EN8

Jonathan
07-09-2011, 10:56 PM
If you don't mind me asking, where can I find the rack at that price? I've been googling away and only managed to find some on ebay for 56 a metre, I must be looking for the wrong stuff :cry:

This is the place:

http://www.wmh-trans.co.uk/

I got my steel box section from Adey Steel. Good prices but not sure what postage would be if available...

Edit: Looks like Jazz beat me to it...

trounce
08-09-2011, 12:32 AM
Awesome, thanks very much

JAZZCNC
08-09-2011, 01:22 AM
I saw a very nice belt driven home build on youtube and I'm very tempted to use this on the X & Y axis, Im presuming that due to the size of my machine I would need two motors on the Y axis as apposed to just one on the machine I saw as it was much smaller?

Hi Neil,

Sorry didn't notice this bit, read that meny posts I tend to skim things and miss bits. . .Lol

Post the link and lets have a look.!. . . but NO you shouldn't need 2 motors just one decent size connected to a shaft linking the 2 sides.
With Belts you tend to have quit high reduction to get the resolution down to something usable (for your needs something in the 20mm pitch range) and this reduction ups the torque which helps the motor. The trick is getting the reduction right so the meat of the motors torque is delivered at the optimum feed rate (for nema 34 this usually around 600rpm) and still give good resolution.


Problem with belts at the lengths you need for the long axis is keeping them tight enough they don't flap around but not so tight the stretch. . . . . So Something to consider could be switching from the conventional narrow gantry layout moving along the long axis and instead have a long gantry moving across the short axis.? This way you could use short twin motor driven belts on the narrow axis and R&P on the other long axis. . . . OR even ballscrews on the short axis.? Chinese ballscrews won't cost much more than belts,pulleys,bearing blocks etc so something I'd consider and ballscrews are very much easier to impliment.!

GTJim
08-09-2011, 09:08 AM
JAZZCNC you have given some excellent advice in this and other threads and I am sure that myself and others will benefit for your experience.
A question, how does rack and pinion compare to ball screws in repeatibilty and accuracy, and does the pinion ever jump teeth under load?
Sorry if this sound dim, but curious.

trounce
08-09-2011, 05:59 PM
One last question before I get designing....
4489

As you can see by this image the sheets of 8 x 4 I'll be cutting get used almost right up to the edge of the wood. I will obviously need a frame which is larger so the router will be able to travel past the edge of the wood, I'm thinking 9 x 5 does this sound about right?

JAZZCNC
08-09-2011, 06:02 PM
JAZZCNC you have given some excellent advice in this and other threads and I am sure that myself and others will benefit for your experience.
A question, how does rack and pinion compare to ball screws in repeatibilty and accuracy, and does the pinion ever jump teeth under load?
Sorry if this sound dim, but curious.

Well Jim the honest answer would be they don't compare.! Infact if you asked me too place each system in numerical order of effeiciency, repeatabilty and accurecy then R&P would probably come 4th. . . . 1st ballscrews, 2nd lead screws close 3rd belt drive then R&P.!!

That said it's doesn't mean it's rubbish and for large format machines doing lower precision jobs but with high loads and cutting feeds then it's usually the best option.

Ballscrews (and Lead) are too whippy over long length's without taking special measure's IE: rotating nuts or excessive sized screws,(which brings other issue's) plus the accurecy and precision they produce hisn't often required for cutting wood and plastics etc which most large format machines are used for.

Belts are very accurate, effiecent with very good repeatabilty, virtually no backlash. But again they have there issue's over large length's and don't handle high loads as good as R&P. They can be made do-able for large machines but not ideal . . . More suited to large machines with low loads and high speeds.

So IMO R&P is the best all round option for a large format machine with high loads (IE: heavy gantry,deep DOC) needing medium accurecy with resonable repeatabilty and high-ish feed rates. . . Perfect for Cutting wood, plastics, stone.

Regards jumping It's not an issue if designed correctly with correct alignment and pinion tensioning into the rack. The issue's can come from debries getting in-between the rack & pinion but if the rack is positioned with the teeth facing down with the pinion engaged by spring loading into it rack from benneth and positioned out of the firing line as much as possible then it's not an issue normally.
The trick is getting the tensioning just right so it's not so weak it allows teeth too jump or have excessive backlash but at the same time not to high cause's binding which helps to reduce backlash (too a point) and jumping but cause's excessive wear. The required tension will vary from machine to machine depending gantry weight, cutting forces etc and a little setup & adjustment will be required at first but ounce setup it works good for this size an type of machine.

Again at the end of the day it's horse's for course's.! . . . . If you want super precise get a show jumper(screws), if you want light weight and speed get a stallion(belts), if you want a good strong all round work horse then get a shirehorse.(R&P) . . . . . If you want an old knackerd Donkey get some threaded bar and MDF. .:whistling:

JAZZCNC
08-09-2011, 06:55 PM
One last question before I get designing....
4489

As you can see by this image the sheets of 8 x 4 I'll be cutting get used almost right up to the edge of the wood. I will obviously need a frame which is larger so the router will be able to travel past the edge of the wood, I'm thinking 9 x 5 does this sound about right?

Not a straight forward yes or no. It will depend on a couple of measurements of the machine to how much extra length and width past the desired cutting area.

First I call the long axis X (length) and Y axis (width) is narrow, Z axis(Up,down) runs along the gantry or Y axis.

Regards Y axis(width) you will want it Just a bit wider than the width of the Z axis, basicly half the width of Z axis at each side plus a bit of stopping room.
The Z axis width will more than likely be determined by the bearings and screw used or the width of the router mounting plate. Wider is stronger because it positions the bearings on the Y axis further apart but wastes travel needing wider Y axis and machine. 200mm is a good width and will fit most routers and spindles plus allow for resonable Y axis bearing placement without wasting travel. 150mm is about the minimum I'd use for a good Zaxis.

Regards the X axis(length) well this depends on the position of the gantry cross beam on Xaxis bearing plates and how far off the front of the gantry the Z axis sticks plus the spindle or router used.
This will ultimatly give you the cutters position relative to where it falls in line with the X axis bearings, this will give you the needed extra for the X axis.

I try to position gantry cross beam back slightly from centre of the X axis bearings so that the cutter position basicly lines up with the front edge of the bearings.
This keeps everything contained within the X axis bearing plate length and nicely balanced weight distribution on the bearings.
No matter how you do it you have to have lose some wasted space at one end or the other.! . . Some sweep the gantry sides back and half the loss at each end.?
I just keep the loss at one end. . . you can always use this space for 4th axis head then it's not taking any table roomand can be left on.?

Doing it the way I do basicly means adding the length of the X axis bearing plates to the required cutting area.

Hope this makes sense.? If not just ask.

luke11cnc
08-09-2011, 08:05 PM
would he be able to use a chain in stead of a belt jazz

James

Jonathan
08-09-2011, 08:09 PM
would he be able to use a chain in stead of a belt jazz

That's possible yes... but I believe it's more difficult to eliminate the backlash inherent in a chain/sprocket.

JAZZCNC
08-09-2011, 08:48 PM
would he be able to use a chain in stead of a belt jazz

James

Yep every thing jonathan said, plus there's nothing to be gained over R&P in performance or cost, infact it would cost more and perform less. It can't even compete with Belts on any front.
To be off any use you need good quality chain and sprockets which arnt cheap. Cheap chain stretchs like crazy untill settled down, It needs dry lubing and crap gets into the links plus it's noisy as hell.! (Mind R&P aint exactly quite.!)

Basicly IMO it's not cost affective enough to give good performance without using expensive chain & sprockets so then whats the point.? . . . . . Unless your names Renthal and you own a chain factory. . . . there's far better options.

Suppose it's further up the horse scale than threaded bar thou.! . . . but not much. .:rofl:

Edit: That was a joke Chain users and send all complaint's to hell coz I don't give a stuff. .:twisted:

Jonathan
08-09-2011, 09:02 PM
Suppose it's further up the horse scale than threaded bar thou.! . . . but not much. .:rofl:


and two below ACME screws....

JAZZCNC
08-09-2011, 09:20 PM
and two below ACME screws....

Oh be carefull Jon your on sacred ground with the Acme brigade.! . . . They'll be after your Balls (screws).:naughty:

trounce
08-09-2011, 10:05 PM
Sorry JAZZ mean't to post that that link to the belt driven machine and totally forgot..


http://www.youtube.com/watch?v=7XwM_azm1so

I think I've made my mind up now to go with R&P instead of the belt. I need to start with something that seems a little more idiot proof and from what I've seen it seems the easiest for me to be able to achieve.

I bought myself the box section today because If I don't start spending I know I'll keep putting this build off and never get it started.
I bought 15m of 60 x 60 x 3 box and 12m of 60 x 30 x 3 for a total of 180 and had the shop cut it into smaller lengths to fit into my van.
This will just be for the bed section and not the legs etc as I'm aiming to put some more pennies away to be able afford alluminium profile for the bottom section or at least some other much lighter alternative that can be unbolted and taken apart.

I think I'm also gonna have to find a way to make the bed come apart aswell or at least some of the supports because If I ever have to move it all I'll need a crane :rofl:

I think with the bed I'm going to go with 9 x 5 to be on the safe side and as these linear bearings come in at 2750mm I may aswell stick to the same length.
http://www.ebay.co.uk/itm/250740973530?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

Again thanks so much for all the replys, I hate asking so many questions but this is so alien to me and quite bamboozling at times :eek:


(http://www.youtube.com/watch?v=7XwM_azm1so)

Jonathan
08-09-2011, 10:10 PM
Oh be carefull Jon your on sacred ground with the Acme brigade.! . . . They'll be after your Balls (screws).:naughty:

We'll see...

What about using 16mm ballscrews (RM1610) and rotating ballnuts. You save buying the end bearings, and the angular contact bearings aren't so expensive as they're not so big as with 25mm screws. Should get a very decent feedrate. Just a thought...

JAZZCNC
08-09-2011, 10:51 PM
What about using 16mm ballscrews (RM1610) and rotating ballnuts. You save buying the end bearings, and the angular contact bearings aren't so expensive as they're not so big as with 25mm screws. Should get a very decent feedrate. Just a thought...

Yes if it was me I'd be seriously considering it. . . I'm a massive ballscrew fan has you know.!

But I was giving easy options that could be bought off the shelf at sensible money. Rotating nut is OK if you have the equipment IE: Mill etc and knowledge to make one. Don't think neil has the equipment.? The knowledge could be gained but probably daunting for someone new and was aiming my suggestions with this newness in mind.!

Think I'd also go with a higher 20mm pitch if being used solely for cutting woods n plastics so the cutting feed is in the meat of the motors torque. Reason being think for a machine this size nema34 would be needed and they don't spin as fast as 23's so with 10mm pitch then gearing would be needed to bring the speeds/feeds up and that will affect the torque.
You have to think when cutting wood you need high feeds and deep DOC for best performance and even faster for plastics, so better to put the right pitch screws on in the first place than use gearing IMO. . . . . Back to horse's for course's. .:confused:

JAZZCNC
08-09-2011, 11:05 PM
I hate asking so many questions but this is so alien to me and quite bamboozling at times :eek:
[/URL]

No you should ask no matter how alien or embarrassed you feel asking. We have all been where you are today so know exactly how it feels. . . .Ask away then ask some more.

Jonathan
08-09-2011, 11:07 PM
But I was giving easy options that could be bought off the shelf at sensible money

Welcome to buy one from my shelf...


Think I'd also go with a higher 20mm pitch if being used solely for cutting woods n plastics

Same, but you couldn't get 20mm pitch from eBay seller last time I checked. I would have done the same otherwise.
Thinking about it since end machining isn't strictly neccecary with a rotating ballnut setup (helps, but I reckon you could do it without by making mounts that clamp the screws, rather like the mounts for round rails) you could buy the 20mm pitch ballscrew from Zapp without spending 7.5*10^99 on end machining. This one:

http://www.zappautomation.co.uk/r1616-ballscrew-p-99.html?osCsid=95f0d7f9b0712bb5af121c620028629f

or

http://www.zappautomation.co.uk/r2020-ballscrew-p-444.html?osCsid=95f0d7f9b0712bb5af121c620028629f


Oh, just noticed the ball-nuts are a bit pricey ... shame.
I'd love to try it with some 20mm pitch screws and big motors / servos and see just how fast you can get with rotating nuts.

JAZZCNC
08-09-2011, 11:46 PM
I'd love to try it with some 20mm pitch screws and big motors / servos and see just how fast you can get with rotating nuts.

Jonathan Don't understand the facination with speed.? . . . It's only any good upto a point then it's a waste. It's like very high rapid speeds there only of any use on certain types of jobs but in the main there useless and come at too costly a price.! . . . . Impressive, great for bragging right's but mostly pointless.

To be of any real use and cutt at high feed rates you need fast high horse power spindles, expensize tooling and a very ridged machines which can handle the force's involved

The cutter and material specs mostly dictate feeds anyway so IMO most high pitch screws are more than enough when it comes to DIY cnc and even small production use.

Jonathan
09-09-2011, 03:35 PM
I know up to a point extra speed gives diminishing returns. Sometimes it just compensates for bad Gcode with lots of G0's. It would be good if you wanted to add a laser ... though of course there's easier ways to move just a laser.

JAZZCNC
09-09-2011, 06:36 PM
This will just be for the bed section and not the legs etc as I'm aiming to put some more pennies away to be able afford alluminium profile for the bottom section or at least some other much lighter alternative that can be unbolted and taken apart.

I think I'm also gonna have to find a way to make the bed come apart aswell or at least some of the supports because If I ever have to move it all I'll need a crane :rofl:
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Hi Neil,

Here's a bit of outside the box thinking to give your grey matter a workout.? . . . If your tight on space why not make a wall mounted router, a bit like a panel saw.:surprised:
There's no rules that says you have to work flat.! The advantages are meny with very few if any disadvantages.? . . Let me expand on the minus's & plus's.

99% of the time you'll clamp material to the bed, even offcuts you'll clamp so they dont get pulled/pushed into cutters path. So no real disadvantage being vertical or inclined.
The plus's being gravity will help greatly with chip clearance and all the crap falling into a catch tray or vac funnel you could build into the bottom.

If mounted so the gantry moves left to right or long axis length ways then the only Axis fighting gravity is the Z axis moving along the Yaxis and this is no big deal because your not lifting/lowering a real heavy mass so with the correct size motor/gearing it won't be a problem.
Though depending how or what you use for linear motion you may need to park it at the bottom when motors are disengaged to stop backdrive. If you use R&P with a worm drive then it wont back drive.!

The foot print on the shop floor Space is a massive saving (Obviosly you'll need a free wall long enough).
Being mounted on the wall you wont need quite as much material because you dont need to build all the frame work to bring it upto a working height. . . . Basicly it would be like building it to sit directly on the floor, with just a small frame to give a slight incline off the wall.
Also very easy to build wheels onto the frame work base for moving, would basicly go thru most workshop single door ways.

Being wall mounted and only standing off the wall a few feet it will basicly take the space of a large wardrobe.! Being like a wardrobe it thens makes it very easy to build a simple frame around it with 2 narrow sides(Or 1 if placed in corner) and folding doors on the front.? . . . Now it's a cabinet router with all the dust and crap contained leaving a nice clean workshop.! (Like mine.:rofl:) The important computer and control box could be mounted outside on one of the end panels for easy access.

So few disadvantages but several very usefull and easily implimented Advantages.

My next Mill will be built on this principle but with a twist I'll keep for another day. .:naughty:

Certainly food for thought.!

Edit: I've often thought to chop the legs off my machine and hang it off the wall and one day when I've nothing to do it may very well happen. . . Winters coming.:naughty:

Jonathan
09-09-2011, 07:24 PM
I was originally going to mount my router to the roof, so at a bit of an odd angle. This was due to space. In the end I did mount it on the floor as I persuaded my Dad there was enough space.

JAZZCNC
09-09-2011, 07:34 PM
I was originally going to mount my router to the roof, so at a bit of an odd angle. This was due to space. In the end I did mount it on the floor as I persuaded my Dad there was enough space.

Nah would give ya neck ache and a 10mm single flute cutter in the eye hurts like shit. .:tup:

luke11cnc
09-09-2011, 08:23 PM
all I'm going to say is hee hee hee

James

trounce
09-09-2011, 09:32 PM
The space issue is really only a problem whilst its being built, I have a galvanised shed in the garden that's 10' x 12' so as long as it fits in there I'll be ok. My main concern was actually moving it because I'll be building it in a garage that I rent next to my house.
I've designed the bed so that a large chunk of the inner supports can be unbolted and removed to make it much lighter when moving it, though I'm not sure if all these supports are really needed.

The outer grey sections will be welded together and the inner sections will be bolted to the frame, though I may get rid of the centre bolts and just have a fully welded cross shape in each inner section.
Outer is 60 x 60 x 3 and the inner pieces are 60 x 30 x 3.
This is my first attempt using google sketch up and I'm pretty chuffed with the outcome :tup:

If you could let me know if it looks ok or if its overkill with all the inner sections?
Cheers
Neill

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Jonathan
09-09-2011, 11:00 PM
If you could let me know if it looks ok or if its overkill with all the inner sections?


I don't think there's really such thing as overkill for the machine bed. Strong/heavy is good. Might be easiest to leave what you have bolted as it's easier to align and wont warp.

JAZZCNC
10-09-2011, 12:15 AM
This is my first attempt using google sketch up and I'm pretty chuffed with the outcome :tup:

If you could let me know if it looks ok or if its overkill with all the inner sections?
Cheers
Neill


Good job that man.!:toot:
Drawing accurate plans helps so much with layout and finding any un seen or unpredicted problems.

No it's not overkill at all just enough IMO. . . Thou I would have all the inner pieces running the same way, same number 3 per bay all running parallel to each other.
This will reduce the gap between them slightly which helps when plunging.! . . .you'll be surprised how much the bed dips when plunging so the less the gaps the more ridged it will be.

Would also put some corner braces in to help with keeping it square. I know it's a bed and squareness hisn't so important because your working on it rather than to it's squareness, If ya know what I mean.!! . . .but working with everything square just helps things fit together that bit easier.! Esp when you have moved it and need to put it back together.

Keep them coming.

Edit: RE Welding. When your welding the frame don't run long beads of weld and alternate between ends. The goal is to reduce heat build up in one area so move around.

trounce
11-09-2011, 04:45 PM
Little update....
Got all the outer sections cut yesterday and welded together today, now I need to get some flat 3mm sheet for the plates to make all the removable braces.
I was a little worried about getting the cuts perfect but you've gotta love plasma discs for perfect thins cuts :smile:

The frame all measures the same from corner to corner and the gaps between each brace is spot on so I'm pretty chuffed nothing got messed up in the welding process, only thing I was a little concerned about was the weld penetration. There seemed to be quite a lot of weld laying on top even though the welder was set to maximum.
However I moved it all around and nothings fallen of yet so it seems to be ok :rofl:

@JAZZ - I've got 4 offcuts leftover with which I'll use to brace the four corners, when you suggested the removable braces should run the same way and said three per bay that would make 12 in total including the larger 60 x 60 pieces?

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JAZZCNC
11-09-2011, 08:03 PM
@JAZZ - I've got 4 offcuts leftover with which I'll use to brace the four corners, when you suggested the removable braces should run the same way and said three per bay that would make 12 in total including the larger 60 x 60 pieces?


Yep thats what's required IMO 3 piece's, thou it's not much more material than the way you had it in squares.
Don't under build the bed for the sake of bit extra steel, If you must use less steel then at least drill the holes ready and add it later. (Thou before you start using it or never will get fitted.!)

Looking good:toot:. . . keep the pics flowing and we'll turn a blind eye to any chicken shit runs we see. .:lol:

trounce
03-10-2011, 03:03 PM
Its been a while since I've managed to get any more work done on the bed but its now almost finished.
It took me forever to cut all the damn brackets and then drill and tap all the holes but thankfully that tedious job is over and done with :tup:

Just a bit of tidying up on a few of the welds that ended up looking pretty dire and then to give it all a nice coat of paint.


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