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JoeHarris
04-05-2012, 09:57 AM
OK, I have introduced my initial ideas on the intros thread and already received some really useful pointers.

The plan is (after some advice from you guys!) to build an aluminium framed 3 axis 1500x1000mm CNC router driven by 2no. ball screws on the x axis. In order to drive the 2 ball screws on the x axis I intend to use timing belts, linking them to a single stepper motor.

The ball screws will be either 2005 geared up or 1610. So far I am thinking 2005 because of the potential whip issue over such a large distance.

Having decided to go down the HTD timing pulleys/belts route for connecting my steppers to the screws I have a few querys I hope someone can shed some light. Please excuse my ignorance! - I'm here to learn.


My questions are:

01 which belt width / pitch would you recommend for this application?

02 I am unsure as to how the pulleys will be attached to the stepper / ball screw - do you have any photographs, technical manuals or just a description of how this can be achieved?

03 Is the lateral pressure on the screw and motor shaft likely to cause damage to the bearings?

03 If I mount the steppers through 20mm alu plate will this allow enough length in the motor shaft to connect it to the pulley? if not is there a way of extending the shaft?

04 in order to adjust/maintain tension on the x-axis drive system I intend to use idler pulleys - how do the bearings work for these pulleys?

any images people have of successful arrangements would be really useful as I try to move the design of my machine along.

Thanks in advance!

Joe

Web Goblin
04-05-2012, 11:10 AM
I would go for a 5mm pitch 16mm or 20mm wide belt. The pinions can simply be drilled and tapped to accept a grub screw to fix it to the shaft or you could use these : http://uk.rs-online.com/web/p/locking-bushes/4888062/ They are a bit expensive but are really good and are easy to adjust and set the pulley on the shaft in the correct place. Personally I dont like attaching the pinion directly to the motor. The shaft can easlit be extended and supported by and extra bearing or two. If you have a look at my build you can see how I extended the Y Axis motor assembly. This might give you some ideas. You can extend the shaft via a coupling or using a solid bar bored out to take both shafts. An idler pulley is simply for tensioning as you say. Mount it on a sliding block with a bolt for setting the tension with a locking nut to secure it once set. What do you mean by how do the bearings work for the idler pulleys?

Ian

Jonathan
04-05-2012, 01:38 PM
1)I'd use 5mm pitch 15mm wide belts:

http://www.bearingstation.co.uk/products/Belts/Timing_Belts/5M

2) Just a grubscrew is generally fine.

3) No

3 again) Probably not. I generally mill a pocket out of the 20mm plate leaving 4mm or so for the motor to rest on yet still be well supported by the thicker material outside. Bit difficult if you don't have a mill though. You can extend the shaft, but it's a lot of extra parts and expense that shouldn't be necessary.

4) You can use idlers to tension the belt, but it's generally easier to have the motor mount slotted so you can apply tension by pushing against the motor and tightening it down.

Pictures:

594459455946

JoeHarris
06-05-2012, 11:04 AM
Thanks for the replies - I will post some more screen shots when I get some time to progress the design!

John S
06-05-2012, 03:46 PM
Don't listen to Jonathan, he's still learning :wink:

Use http://www.beltingonline.com/5mm-htd-timing-belts-4575 for belts and pulleys, more choice and cheaper.
good service as well

Jonathan
06-05-2012, 04:30 PM
Use http://www.beltingonline.com/5mm-htd-timing-belts-4575 for belts and pulleys, more choice and cheaper.
good service as well

Nice one... bearing station's service has been generally awful. Every order has taken about a week to arrive for me. They post the same way with cheap or expensive service and take ages to despatch so makes no difference. Plus in the last order they sent one wrong pulley and belt. Price is similar for the pulleys but I think I'll not bother with bearing station due to the poor service. I only recommended them before as I thought they were the cheapest.

JAZZCNC
06-05-2012, 08:54 PM
Hi Joe,

Sorry not replyed to some of your previous post's where you asked me directly, I've had eye trouble so time on computer has been limited hence me not being around much.!

Others have answered the belt Q's regards width, pitch etc but there are things you need to be made aware about with this size machine.?
One of the things I found when I built my machine was that long belts where not available in 5 x 15mm HTD so depending on the X axis screw centres you may have the same trouble.?
The X screw centre's on my machine are 1300mm using 30T pulleys so needed belt length over 2750mm the longest HTD 5mm pitch 15mm wide I could find was around 2400-2500mm.
The way I got around it was to have them special made costing around 20 each. I bought 2 keeping one for spare, that was over 3yrs ago and I've only recently swapped for the spare and that was because I left a pulley lose after changing ratios from 1:2 to 1:1 for high resolution job and it fell off killing the belt in the process.!!

Regards mounting pulleys you will need the ballscrew ends machining longer than standard so the shaft goes all the way thru the pulley giving better purchase for the grub screws. Also grind a small flat on the shaft for the grub screw to grip and stop the pulley spinning.
Regards idlers and tension then You don't need lots of tension on the belt and infact if you put them under too much tension they wear quicker and it also puts tension on the ballscrew bearings and if Ott can cause binding and possible missed steps.? Just enough tension to stop the belts flapping around and jumping teeth is all thats needed and lightly tensioned idlers is all thats required. (I just use 2 bearings with large penny repair washers for guides)

I'm posting the pics of my well used setup and While my setup looks ugly and is roughly thrown together it's simple, works very very good and accurate with high reliabilty even thou I run it in some of the worst conditions for running belts.!!
I dont have any guards or shields, the machine mostly 98% of time cuts Aluminium with chips flying every where and it has never failed or lost position either thru skipped teeth or missed steps. While It's capable of max rapids around 11mtr/min with 5mm pitch screw 1:2 ratio(effective 10mm pitch) 6Nm Nema 34 motor running 75Vdc I detune it to 7mtr/min which is more than enough for my needs and also why It's NEVER, NOT WOUNCE missed steps or lost position or sync under cutting conditions or rapid movement.

To give you an idea of the resolution and what 1:2(10mm pitch) belts can achive then I've attached the Aztec calender pic with a link to video see the detail better.

Hope this helps and inspires.!

http://www.youtube.com/watch?v=wjDvimSdH8M&feature=youtu.be

59505951

John S
06-05-2012, 10:23 PM
How big's that Aztec calender ?

Jonathan
06-05-2012, 10:35 PM
How big's that Aztec calender ?

About 150mm.

Here's my attempt with the same G-code:

59545955

That was with 1:1 ratio and 10mm pitch screws...

http://www.youtube.com/watch?v=Gh2pjXQY5U8

Wish I could afford to use the 20mm aluminium waiting on my router bed to make a 740mm one!

John S
06-05-2012, 10:43 PM
What was that programmed in? Aspire ?
Is it flat, it looks curved ? Giz the code, i might cut this in gold, well brass anyway worth more than gold.

Jonathan
06-05-2012, 10:59 PM
What was that programmed in? Aspire ?
Is it flat, it looks curved ? Giz the code, i might cut this in gold, well brass anyway worth more than gold.

Yes aspire, Jazz did it.
Not curved, hmm.. could use CNCtoolkit to wrap it round a profile. Finally an excuse to make the 5-axis spindle mount!

JAZZCNC
06-05-2012, 11:00 PM
What was that programmed in? Aspire ?
Is it flat, it looks curved ? Giz the code, i might cut this in gold, well brass anyway worth more than gold.

On it's way to you now, we'll call it straight swop for ferrari.!!

John S
06-05-2012, 11:41 PM
Ta, got it.
Also found the DXF for it.
Translated onto brass at 120mm round 20 degree V carve it says 2 hours 57 cutting
90 degree cutter is 1 hour 43

Jonathan
06-05-2012, 11:48 PM
Probably got it twice.

I think 20 degree will cut a bit too deep? I doubt the time estimates will be anywhere near unless your machine acceleration is exceptionally high. Still it'll be interesting to find out.

Web Goblin
07-05-2012, 12:00 AM
Any chance of a copy of the code as well?:encouragement:

Thanks.

JAZZCNC
07-05-2012, 12:02 AM
90 degree cutter is 1 hour 43

If I remember right thats roughly about what it took me when I did it.?? But it's been that long since I did it I can't remember.

Like Jon says 20 deg will cut deep but I'm sure you will have sussed that and limited it's depth.? I've seen a nice one done with aspire that cuts the bottoms of deep area's flat and rest Vcarved.

JAZZCNC
07-05-2012, 12:05 AM
Any chance of a copy of the code as well?:encouragement:

Thanks.

Problem is it's 17Mb file (5Mb zipped) with 850,000 lines of code.!!

PM me a email and I'll fire it over.

Web Goblin
07-05-2012, 12:13 AM
Thanks JAZZ. pm sent.

Ian

JAZZCNC
07-05-2012, 12:27 AM
Thanks JAZZ. pm sent.

Ian

You have mail.!!

Web Goblin
07-05-2012, 12:32 AM
Got it thanks!
What size/type cutters did you use for it?

Ian

John S
07-05-2012, 12:35 AM
yes limited depth of cut to 1.8mm, was 0.8mm so it flat bottoms larger area's. That adden 3 minutes to it according to VCarve at 1min:46

Simulated it in Mach and got 2 hours 33.

JAZZCNC
07-05-2012, 12:49 AM
Got it thanks!
What size/type cutters did you use for it?

Ian

I used a simple 6mm 90deg spot drill.

Web Goblin
07-05-2012, 12:52 AM
Thanks again JAZZ. Need to have a look for some of them now.

Ian

Web Goblin
07-05-2012, 12:55 AM
Just thinking about the spot drill. I have a few chipped single flute 6mm mills. I wonder how one of them would do reground to 90Deg?

Ian

JAZZCNC
07-05-2012, 01:08 AM
yes limited depth of cut to 1.8mm, was 0.8mm so it flat bottoms larger area's. That adden 3 minutes to it according to VCarve at 1min:46

Simulated it in Mach and got 2 hours 33.

Seem to remember that I 200% over ride the feed rate and was maxing out around 800mm/min.!!

JAZZCNC
07-05-2012, 01:14 AM
Just thinking about the spot drill. I have a few chipped single flute 6mm mills. I wonder how one of them would do reground to 90Deg?

Ian

Can't see a problem if ground well.? I couldn't belive the results with TC spot drill so if you have the abilty to grind your own then should get great results.

Jonathan
07-05-2012, 01:32 AM
Just make sure whatever you use is ground to a sharp point. Some spot drills still have a web so you need to be careful.

I tend to regrind my 6mm single flute cutters back into the same cutter. Something useful to do whilst the router is running.

JoeHarris
09-05-2012, 01:21 AM
Ha ha looks like my build log got high-jacked only a couple of days in!! Looks amazing though. Thanks for the further info Jazz and hope your eyes are ok. I will try to get images of progress up in a few days...

JAZZCNC
09-05-2012, 05:29 PM
Ha ha looks like my build log got high-jacked only a couple of days in!!

Ye full of pirates and bandit's this place John S being Captain black beard . . " Argh argh yeh bastards who's swipped mi Hobnobs.!!"

Anyway don't complain too much because when you do have it cutting and wanting something to impress the Mrs you wont have to try remembering which post ya saw that Aztec calendar. . .Lol

JoeHarris
10-05-2012, 02:37 PM
Anyway don't complain too much because when you do have it cutting and wanting something to impress the Mrs you wont have to try remembering which post ya saw that Aztec calendar. . .Lol

Oh I'm not complaining, just a tad jealous - need to be patient!

JoeHarris
16-05-2012, 09:31 PM
OK!

Finally got round to making some progress on the model of my machine. I have made a load of changes / developments based on your very helpful comments so far. I have uploaded some screen shots and an honest appraisal would be very much appreciated, together with any ways you can think of to make it cheaper!!

Thanks again to all who take a look at this.

Joe

p.s.for anyone who is interested this thread started at http://www.mycncuk.com/forums/showthread.php/4489-Hello

5999600360026001600059985997599659956004

Jonathan
16-05-2012, 10:34 PM
Currently the number of teeth on the X-axis motor pulley engaged with the belt is too small - it will slip. You should put an idler either side of the motor pulley to force the belt to wrap around it.

The travel on the Y-axis is limited by when the Z-axis makes contact with the X bearing block support, so there is a gap between the position of the Y bearing blocks at this limit and the gantry sides. Therefore you could space the Y-bearing blocks out further (with longer rails to match) to add strength without compromising travel.

The piece of aluminium extrusion underneath the gantry that links the two sides doesn't really add any strength since the gantry is well supported there by the ballnuts. I would get rid of that extrusion and clearly shorten the gantry sides where it was. The Z-motor mount can also be made narrower near the motor to save material.

JAZZCNC
17-05-2012, 02:42 AM
I see the same things Jonathan does but I also see other few factors that you may want to consider.? Some regards build design, some practicle usage considerations.

#1 The distance from the lower bed to spindle appears to be approx 100mm.? You also have drawn a sub base which would guess being 19mm MDF spoil board.? That leaves 81mm total distance for material and tooling. Basicly giving a Max tooling length and material thru cut of capabilty of 40mm which hisn't much.! . Most drill flutes alone can be longer than 40mm, even a short endmill will stickout from spindle 20-30mm so unless you only plan on cutting thin material I would look to increase in height in this department.

#2 Consider how you will mount the X axis bearings to the plates and still have access to the screws.? The way you have it drawn at the minute the profile will cover the holes unless you install the profile after. Idealy you would want the bearing plate,profile and gantry sides to all be bolted together for Max strength but the way you have it at the minute this wont be possible and way it is will make setting up the machine regards squareness etc a pain.
An easy fix would be to have 2 bearing plates, one which mounts to the bearings the other part of the whole gantry which bolts to the bearing plate.

#3 The bed supports all run length ways.? I would run all inner or at least one central width ways with 2 length ways offset as the shorter length beams will be stronger reducing bed flex and beefing the frame up in all direstions and esp the long length.

#4 Check the linear rails base will fit the profile width, some are wide and the mounting holes may fall in the wrong place were there's no much material in the profile or directly inline with profile internal structure making drilling amd tapping very difficult.?
Often it's better to mount a wider plate to the profile then mount the rails to the plate, it certainly makes drilling and tapping far easier.

Hope these things are usefull.

JoeHarris
17-05-2012, 11:52 PM
Thanks both for the advice, I will update and post again!
Are you sure about removing the y axis profile under the bed i thought this would stiffen up the y axis without putting extra strain on the screws? The 100mm dim on the z axis is from the bottom of the z axis mount to the top of 18mm mdf / alu plate bed btw...
Joe

JAZZCNC
18-05-2012, 02:51 PM
Are you sure about removing the y axis profile under the bed i thought this would stiffen up the y axis without putting extra strain on the screws?

Yep it doesn't really add much stength other than supporting the sides which dont need it because the screws do that. The savings in both money and weight out way the little it if any does add.



The 100mm dim on the z axis is from the bottom of the z axis mount to the top of 18mm mdf / alu plate bed btw...
Joe

Yep thats what I thought but still not a great deal of clearence and I think you'll find there'll be a day not long into it's life when you'd wished you'd made it higher because you can't fit material and tool in the space.? Obviously only you know the main use so can judge better but it does or will limit it's potential.!! Another 50mm won't weaken the machine and will make machine far more versatile IMO.

JoeHarris
10-07-2012, 02:33 PM
Man - I cannot believe how long it has taken for me to find the time to upload some more to this thread.

I have reworked the Z axis a little to take on some of the comments - images attached bellow and as usual comments more than welcome.

The main changes are double plates to attach the y axis uprights to the bearing blocks to allow for adjustment and an increase from 100mm from the bottom of the z axis mount to the top of the bed to 150, giving 132mm clear if an 18mm sacrificial board is used on top of the bed.

I am now quite close to saving up enough to buy the first batch of parts and could do with some guidance on ordering bespoke end machine for the ball screws to allow for the pulleys to be mounted. Jazz had mentioned having them machined longer than usual - would about 100mm extra suffice?? Also did you have the diameter machined down too to receive the pullies?? many thanks in advance63166317

JoeHarris
17-07-2012, 02:24 PM
As I have no way of machining the aluminium plate apart from drilling holes - I have had thought that I would like to float.
If I was to temporarily replace all of the alu plate for MDF which I could route by hand - would I be able to then use the machine itself to machine the aluminium parts or is MDF too unstable and flexible to make this worthwhile? Has anyone done this in the past or did you all have metal working mills and lathes in your garages and sheds?!

Iwant1
17-07-2012, 03:20 PM
I'm in you're boat with just a drill press, and saws. There's plenty of good guys here that will help you machine the parts you need and would be cheaper than outsourcing to an engineering firm. Rather than spend on building an MDF router then spend more to upgrade it later, I would pay someone to machine the parts first time around. You could put your requirements in the request threads, but I'm sure someone will contact you here with help.

Adil

JAZZCNC
17-07-2012, 06:55 PM
As I have no way of machining the aluminium plate apart from drilling holes - I have had thought that I would like to float.
If I was to temporarily replace all of the alu plate for MDF which I could route by hand - would I be able to then use the machine itself to machine the aluminium parts or is MDF too unstable and flexible to make this worthwhile? Has anyone done this in the past or did you all have metal working mills and lathes in your garages and sheds?!

It could be done but you would have to beef up the MDF parts considerably to cut aluminium and then take it careeful with the DOC.

I cut some of the parts for my first machine in Aluminium by hand using MDF templates and bearing guided cutter and very shallow pass's.!! . . .You need to be used to working with a powerfull router and have confidence and take it slow but it's do-able.! . . (scary as hell at first but soon settle down.)

Jonathan
17-07-2012, 07:21 PM
I am now quite close to saving up enough to buy the first batch of parts and could do with some guidance on ordering bespoke end machine for the ball screws to allow for the pulleys to be mounted. Jazz had mentioned having them machined longer than usual - would about 100mm extra suffice?? Also did you have the diameter machined down too to receive the pullies?? many thanks in advance


To add pulleys you want to increase the length of the bit the pulley mounts on as on the standard drawings it's 15mm, so I always ask Ghai to 'increase dimension F on end machining to 25mm for pulley'. That makes it much easier to align the motor and screw pulley, but clearly you'll need to add 10mm to the length of screw to compensate...The standard diameter for that bit is 10mm, but you may want to consider having that 8mm (same as motors) you can easily swap the pulleys round if required.
This is the end-machining drawing Chai (linearmotionbearings2008) sent me:

6375


Has anyone done this in the past or did you all have metal working mills and lathes in your garages and sheds?!

Yep, I got the mill first and used that to make the router. My milling machine was 320 on eBay from someone local, so if you can find a good deal I strongly advise getting one as they're so useful just in general. You might even be able to get one second hand, make the router, flog it and be in profit.

JoeHarris
18-07-2012, 12:01 AM
Thanks Guys, Chai has given me a quote including 50mm extra machining - wanted to be on the safe side in case the design changes!

He seems pretty reasonable, I wanted to go with "proper" linear rails but when you can get change from 30 for a 1500mm long SBR20....

JoeHarris
31-07-2012, 01:58 PM
I think another thumbs up for Chai is in order...

JoeHarris
31-07-2012, 02:07 PM
I know you have all seen these bits and pieces a 1000 times before, but I'm excited :nevreness: so heres a picture of what arrived yesterday from china.6459
The BK/BF Support blocks seem a nice snug fit - any techniques for getting them on (and off!) - I don't want to set about them with a rubber mallet just yet. Also does anyone have any thoughts on lubricating ballnuts? how often and what to use...?

JAZZCNC
31-07-2012, 06:03 PM
The BK/BF can be a tight fit so a light flick round the shaft with some fine emery is some times required. They can be pulled on/off with even pressure but some times you will need to give them a very very light tap evenly on either side with rubber mallet.

Thing to watch out for is the rubber bearing seal rubbing on the screw causing binding when butted up to the little spacer. Some times you'll need to either add another spacer or push the seal in further, just be careful not to push in so far it rubs on the bearings.
Also don't tighten the nut like nut and bolt just nip it up enough to take the play out then lock with grub screws. If you over tighten you'll cause binding and wear the bearings quickly. After a week or so running then re-check for any settle movement.


The ball-screws I just use light way oil pumped into the nuts every so often. You don't need much for every day use and it should just leave a very light film on the screw after running up & down it's length. If the screw is dripping or blatherd then thats too much.!! Every now and again I'll pump loads of oil thru the nut to flush any crap out.

JoeHarris
12-10-2012, 05:45 PM
Hello all, thought I would upload some images of the design so far - a lot has changed since the last ones... As always comments most welcome!

7121712271237124

JoeHarris
17-10-2012, 10:03 AM
Further to my previous post I have some questions:

1) to drive the two ball screws on the x axis I am using a belt driven by one stepper and driver. I am doing this because of fear of missed steps. If I use digital drivers (not closed loop) does this issue go away?

2) if I stick with the belt drive arrangement shown does it matter where the motor is placed in the belt loop. I have shown it off to one side currently, I had it in the middle previously? I figure it shouldn't make a difference? Probably need to add in another idler though.

3) the four sides of the base of the machine is comprised of two aluminium plates fixed to the ends of two aluminium profiles. These sit onto a series of aluminium box sections. I have no cross bracing in this frame. Would it be prudent to add some in??

I intend to build the timber table next so I have a base to work up from - any comment would be greatly appreciated before it is too late!!

irving2008
17-10-2012, 10:37 AM
Further to my previous post I have some questions:

1) to drive the two ball screws on the x axis I am using a belt driven by one stepper and driver. I am doing this because of fear of missed steps. If I use digital drivers (not closed loop) does this issue go away?

No, even digital drivers can miss steps. A stepper only misses steps if you're asking it to perform outside its torque curve. As long as the torque available at the speed/acceleration you are operating it at is sufficient to move the motor onto the next step, or prevent it moving to the next step when inertia comes into play on deceleration then it'll be fine. Microstepping makes it much harder and the risk much higher esp if you go over 1/4step.

2) if I stick with the belt drive arrangement shown does it matter where the motor is placed in the belt loop. I have shown it off to one side currently, I had it in the middle previously? I figure it shouldn't make a difference? Probably need to add in another idler though.

Shouldnt make any difference as long as belt tension is sufficient to maintain meshing with the pulleys, tho avoiding long unsupported runs of belt reduces the possibility of skipping a tooth due to belt 'flap'

3) the four sides of the base of the machine is comprised of two aluminium plates fixed to the ends of two aluminium profiles. These sit onto a series of aluminium box sections. I have no cross bracing in this frame. Would it be prudent to add some in??

If you mean diagonal bracing, then yes it wouldnt hurt

I intend to build the timber table next so I have a base to work up from - any comment would be greatly appreciated before it is too late!!

Good luck!

Jonathan
17-10-2012, 10:51 AM
Some of the digital drivers have a stall-detect feature which changes an output on the driver if the motor stalls. You can connect this to the e-stop so that the machine stops moving to prevent any damage should only one of two motors stall. However I don't think this feature alone is that big an advantage since if you're stepper motors are stalling, even just occasionally, then there is something wrong with the system - either you are trying to get too high acceleration/speed from the motors or there's a mechanical fault. If there's something causing the motors to stall then one should find the problem, not compensate with a safety feature.

Once you have tuned the motors properly they will not miss steps or stall. Plenty of people, myself included, use two stepper motors on their X-axis with standard drivers and do not have problems.

JAZZCNC
17-10-2012, 11:08 AM
Further to my previous post I have some questions:

1) to drive the two ball screws on the x axis I am using a belt driven by one stepper and driver. I am doing this because of fear of missed steps. If I use digital drivers (not closed loop) does this issue go away?

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.


2) if I stick with the belt drive arrangement shown does it matter where the motor is placed in the belt loop. I have shown it off to one side currently, I had it in the middle previously? I figure it shouldn't make a difference? Probably need to add in another idler though.

No don't make much difference other than you have 2 long lengths of belt to handle flap so in the middle limits this slightly.


3) the four sides of the base of the machine is comprised of two aluminium plates fixed to the ends of two aluminium profiles. These sit onto a series of aluminium box sections. I have no cross bracing in this frame. Would it be prudent to add some in??

Absolutely bracing never hurts.!! Even a little is Certainly better than none and the moving mass of the gantry decelerating from speed will easily twist an unbraced frame.

JoeHarris
17-10-2012, 02:15 PM
Thanks guys. For the bracing - some 20x6mm thick aluminium flat bar arranged in a big X across the base should do it ?

D.C.
17-10-2012, 11:44 PM
You may want to check with the machinists instead of the guest muppet, but I think thinner angle or better yet box section would be a lot better for bracing than flat bar if your design will allow it, flat will flex too much?

m.marino
18-10-2012, 09:51 AM
I know others have chimed in and given very good information, my two cents is as follows:


Further to my previous post I have some questions:

1) to drive the two ball screws on the x axis I am using a belt driven by one stepper and driver. I am doing this because of fear of missed steps. If I use digital drivers (not closed loop) does this issue go away?

No digital driver do not remove the risk of missed steps. I am running twin screws with twin drives (one slaved to the other via Mach) and using digital drives (the very AM882's that Jazz refers to). I had been running them at 8.5m/min velocity and 1.75m/sec^2 acceleration for a good while, without any stalling what so ever at all. That was for the X axis as each one I tune a bit different. I am using 1605 ballscrews and direct drive. Currently I am running them at 8m/min V and 1.5m/sec^2 A and the little bit of jerkiness that was present has gone. Running a good solid voltage for the motors helps a lot. Currently running 60V and will be running 68V when I finish building the new power supply (almost have al the parts and slowly getting comfortable with how to d o it correctly).

2) if I stick with the belt drive arrangement shown does it matter where the motor is placed in the belt loop. I have shown it off to one side currently, I had it in the middle previously? I figure it shouldn't make a difference? Probably need to add in another idler though.

I will leave this to those who have experience with belt drive systems.

3) the four sides of the base of the machine is comprised of two aluminium plates fixed to the ends of two aluminium profiles. These sit onto a series of aluminium box sections. I have no cross bracing in this frame. Would it be prudent to add some in??

Yes, rigidity is your friend as long as it does NOT cause binding or increase enertia unduly.

I intend to build the timber table next so I have a base to work up from - any comment would be greatly appreciated before it is too late!!

Yes when building your table do the best you can to make sure the surface is truly flat and set up points with which to bolt the machine to it so that once built the timber frame can be secured and act as additional part of the rigid structure to help absorb vibration from the machine.


Good luck and keep asking, will help as able.

Michael

JoeHarris
21-10-2012, 11:11 AM
The more I think about how to brace this thing up I am moving towards a metal frame rather than timber. I would keep all of the aluminium profile and plate as is but bolt this down to a steel box frame. The question is, is it worth buying an arc welder and learning to weld for the gains in strength and hopefully accuracy??

irving2008
21-10-2012, 11:35 AM
Learning to weld is a skill thats worthwhile in itself. The thing about welding up a steel frame is that unless you are careful it will distort with the heat. The mistake that most beginners make (and I include myself in that as I'm not an expert welder, I just get by) is to try and weld too much in one go. The trick is to tack things in place then go back and fill the gaps so to speak. You dont need to seam weld everything. Personally I'd go with a MIG welder rather than an arc/stick welder. Its easier to strike the arc and get a good finish. While a steel box won't necessarily improve accuracy it will improve rigidity and you can still use wood with steel; a basic 4-sided bed with 4 legs of steel and a carcass of mdf bolted over will give it rigidity (and turn the base into a useful cabinet)

martin54
21-10-2012, 02:10 PM
Like irving has said welding is a useful skill to have but like anything does take a bit of practice to get right. Mig is certainly easier to learn than stick & probably more forgiving in that it is easier to keep a run going. Steel is pretty cheap to buy so the practice doesn't really cost a lot. If you picked up a decent second hand mig machine you would probably be able to sell it on if you decided not to keep it for much the same as you paid for it so would only really be borrowing it for your build.
Even with buying a welder a steel frame will probably work out cheaper than an aluminium frame I would have thought. Can't speak from a cnc point of view though as haven't built a machine yet myself lol.

D.C.
21-10-2012, 02:11 PM
I came to pretty much the same conclusion about using steel, I can upgrade something like a spindle or motor at a later fairly easily to improve the machine but if the frame moves around like a jelly then the whole thing would have to go in the bin and get rebuilt from scratch.

At the moment I'm planning to hold thep pieces of steel together with brackets made from steel angle and bolts so that I can adjust it fairly easily, because of the problems welding seems to cause I'm also considering joining some bits with a metal epoxy. If you need to buy a welder just for this job (the really cheap mig welders won't do 3mm/4mm box properly) the epoxy route would work out cheaper and easier than learning how how to weld on a frame that needs precision work from the get go.

This guy has a lot of useful info for how to approach frame building, while spending 500 on a perfect straight edge to use for alignment may be out of my league there is some good stuff that can be applied on a lower budget.

Machine frame - MadVac CNC (http://www.oneoceankayaks.com/madvac/machine_frame.htm)

martin54
21-10-2012, 02:13 PM
Meant to say if you buy a gas less mig setup you don't have to worry about insurance as far as having gas bottles on the premises goes either. Not used gasless mig myself but know people that do & seems to be little difference.

martin54
21-10-2012, 08:04 PM
That's an interesting read DC, haven't read it all yet but did read the bit about him using an epoxy to basically glue the steel sections together.
Have you done much research on this way of manufacturing a frame? The guy doesn't seem to go into to much detail & I couldn't see much on the link he provided but haven't read that properly either.
He mentioned using west systems 207 which is just a hardener so not sure what resin he used plus there is no mention of ratios for resin, hardener or fillers although there would have to be a low volume of fillers in it if you can pour it.

Determined to get some epoxy in your build somewhere aren't you lol.

JoeHarris
21-10-2012, 08:52 PM
Wow that guy went to some extreme lengths on the accuracy of his frame then only used one screw on the long axis!!! Whoops.

JoeHarris
21-10-2012, 08:55 PM
Thanks for the tips - i'll add 'learn to weld' to the to do list.

D.C.
21-10-2012, 11:53 PM
Sorry for rambling post...

A few people on cnczone seem to swear by it, I've only ever used the stuff before for patching up rust holes in cars not for anything structural but watching this vid impressed me enough to seriously consider it:

DP-420 3M EPOXY overlap shear test by Doctorbass PART 1 - YouTube (http://www.youtube.com/watch?v=3NWzODqhSbw)

(In part two he adds a load more weight and the join holds perfectly)

The thing with welding properly is it does take a lot of practice, if you don't prepare the joint carefully, don't make sure you have good penetration and don't make a consisitent pool in the weld than the strength of the join drops off dramatically, that is why people doing mission critical welding like nuclear power plants or submarines insist on x-ray inspection of every single weld. A weld can look and will look absolutely perfect but still be structurally weak, especially with arc welding where bits of slag can slip into the weld and be completely invisble to you when you have a welding goggle on.

If the people recommending repeated tack welds ever took an x-ray of the joints or sawed through them they would be shocked at how weak the joint they ended up with is in real life, fortunately the amount of steel that gets used for CNC machines is not there for strength, it is there to provided rigidity. (I know nothing about CNC but I can weld...)

Metal epoxy seems to provide more than enough strength for the job of holding a machine together but introduces another problem because the young's modulus of the various epoxy mixes seems to vary between 2-20 Gpa (compared to about 70 for ally or 200 for steel, higher means more rigid). I'm satisfied that any epoxy joint will structurally hold together on a CNC machine but I still haven't worked out what effect joining two pieces of steel together with what is by comparison a bit of rubber will have on the overall performance of the structure.

If I can't determine that my current plan is to build a frame from mild steel box section that is held together using brackets made from steel angle section welded to plate that is bolted to the box section. Enlarging the holes for the bolts mean I can perform accurate positioning before tightening the bolts and secure the joins using metal epoxy. That way I get the benefits of steel on steel rigidity and the epoxy makes sure that it will never move out position but if I welded a 'perfect aligned bolted structure' the thermal shock of the welding would distort the alignment as metal expands and then contracts. Bolting alone would mean loosening of the bolts over time.

My current thoughts anyway!
*Subject to radical change when I get a clue about what I'm doing. :)

irving2008
22-10-2012, 01:11 AM
Have you considered Ally box section and ally welding like this: Durafix UK Ltd - Pages (http://durafix.co.uk/pages.php?&pID=7)

D.C.
22-10-2012, 08:26 AM
Sorry about the thread hijack Joe, you seem to be more of a wood guy and not an engineer so make a cup of tea and read this thread on cnczone:

My First Router, Built in Steel - CNCzone.com-The Largest Machinist Community on the net! (http://www.cnczone.com/forums/cnc_wood_router_project_log/30751-my_first_router_built_steel.html)

A few years ago this english guy Haydn that builds custom guitars built his cnc machine from 80x40x4 steel box section, bolts and epoxy. It is a really great thread because he posts on it over several years and gives lots of details and photos not just of the machine but the work he does on it.

If you check out the mop/abalone inlay work his machine is producing on page 9 I'm pretty sure you will be stunned by what his machine is capable of, exactly what I am aiming for.

It is quite inspiring that a guy with basic wood tools and a drill press can put together a machine like that on a realistic budget. I don't have access to an engineer's flat table but I can work round that by using a few car jacks to get my box section roughly level and then putting a layer of self leveling epoxy on top of them. After reading that thread I'm about 90% sure I can build a similar machine without going over 1500.

If I'm not happy with the rigidity of the machine I will still have the option of pouring some fibre concrete into the gantry and just have to live with a slower machine.

Edit to add: The guy is using the machine to make a living and the epoxy joints are holding up fine after a couple of years of regular use that is good enough for me, long live the epoxy! :)

D-man
23-10-2012, 11:26 PM
Sorry for rambling post...

A few people on cnczone seem to swear by it, I've only ever used the stuff before for patching up rust holes in cars not for anything structural but watching this vid impressed me enough to seriously consider it:

DP-420 3M EPOXY overlap shear test by Doctorbass PART 1 - YouTube (http://www.youtube.com/watch?v=3NWzODqhSbw)

(In part two he adds a load more weight and the join holds perfectly)

The thing with welding properly is it does take a lot of practice, if you don't prepare the joint carefully, don't make sure you have good penetration and don't make a consisitent pool in the weld than the strength of the join drops off dramatically, that is why people doing mission critical welding like nuclear power plants or submarines insist on x-ray inspection of every single weld. A weld can look and will look absolutely perfect but still be structurally weak, especially with arc welding where bits of slag can slip into the weld and be completely invisble to you when you have a welding goggle on.

If the people recommending repeated tack welds ever took an x-ray of the joints or sawed through them they would be shocked at how weak the joint they ended up with is in real life, fortunately the amount of steel that gets used for CNC machines is not there for strength, it is there to provided rigidity. (I know nothing about CNC but I can weld...)

Metal epoxy seems to provide more than enough strength for the job of holding a machine together but introduces another problem because the young's modulus of the various epoxy mixes seems to vary between 2-20 Gpa (compared to about 70 for ally or 200 for steel, higher means more rigid). I'm satisfied that any epoxy joint will structurally hold together on a CNC machine but I still haven't worked out what effect joining two pieces of steel together with what is by comparison a bit of rubber will have on the overall performance of the structure.

If I can't determine that my current plan is to build a frame from mild steel box section that is held together using brackets made from steel angle section welded to plate that is bolted to the box section. Enlarging the holes for the bolts mean I can perform accurate positioning before tightening the bolts and secure the joins using metal epoxy. That way I get the benefits of steel on steel rigidity and the epoxy makes sure that it will never move out position but if I welded a 'perfect aligned bolted structure' the thermal shock of the welding would distort the alignment as metal expands and then contracts. Bolting alone would mean loosening of the bolts over time.

My current thoughts anyway!
*Subject to radical change when I get a clue about what I'm doing. :)

Jesus! That stuff is awesome! I want some! I don't know what for, but I just want it lol

JoeHarris
24-10-2012, 12:05 AM
Have you considered Ally box section and ally welding like this: Durafix UK Ltd - Pages (http://durafix.co.uk/pages.php?&pID=7)

Have you used this stuff ? Is it any good? - Ali box does seem pretty cost effective...

irving2008
24-10-2012, 02:27 AM
Have you used this stuff ? Is it any good? - Ali box does seem pretty cost effective...Yes I have and its pretty good. Easier than welding but like all things needs practice...

JoeHarris
13-11-2012, 06:54 PM
So the design has developed (changed completely) (again!)

Attached images of revised gantry supports and ball screw connection detail. The last image is of some hefty milling in 50mm ali, but should be solid as a rock and looks pretty cool...

I've done this to check it will all assemble OK and to explain my thinking to those who can spot potential pitfalls I may have missed.... Cheers


737773787379738073817382738373847385

WandrinAndy
13-11-2012, 11:01 PM
That's looking great Joe... can definitely see the designer in you coming through with that chunky funky machined bit!

The only thing I can raise is that I think Jazz commented that attaching supported rail to alu profile can be tricky depending on the spacing of the holes and the internal shape and thickness of the extrusion.... maybe you've already checked.... otherwise might be worthwhile checking with somebody who has seen both of these in the flesh so to speak.

I wouldn't worry about changing things completely again.... I'm starting to think that it may be better forever just re-designing in sketchup than ever building the wee beastie... Lol

JoeHarris
13-11-2012, 11:18 PM
I know! One of the benefits of not having any money to spend on it - lots of thinking time!!

JoeHarris
15-11-2012, 10:46 PM
The only thing I can raise is that I think Jazz commented that attaching supported rail to alu profile can be tricky depending on the spacing of the holes and the internal shape and thickness of the extrusion.... maybe you've already checked.... otherwise might be worthwhile checking with somebody who has seen both of these in the flesh so to speak.

From what I can see from drawings of the profile and measuring the sbr20 I've got it should work... Would appreciate it though if someone could tell me for sure otherwise with this combo..

JAZZCNC
16-11-2012, 12:24 AM
Would appreciate it though if someone could tell me for sure otherwise with this combo..

Yep it will be fine.(Just for you joe.:wink:)

Jonathan
16-11-2012, 12:41 AM
It's certainly strong enough, but the 50mm thick aluminium seems a bit over the top. It's a mildly interesting part to machine though so I'd do it cheaply as I tend to charge less if the part is interesting! You could replace it with 2 pieces.

JoeHarris
06-12-2012, 12:55 AM
I am now the proud owner of some shiny new taps :joyous:

WandrinAndy
06-12-2012, 12:40 PM
I am now the proud owner of some shiny new taps :joyous:

Wonder whether the yanks would refer to them as faucets ;-)

JoeHarris
06-01-2013, 09:24 PM
Woohoo! 7890

AdCNC
06-01-2013, 10:08 PM
Did Jonathan make you the X Ball Nut/Endplates? any pics?

JoeHarris
06-01-2013, 10:47 PM
Did Jonathan make you the X Ball Nut/Endplates? any pics?

Not yet, this project is the definition of snails pace. Young children and no money! Just learning to weld at the mo!

Swarfing
06-01-2013, 10:48 PM
Welding wood you should be ashamed of yourself...tck tck tck!

JoeHarris
06-01-2013, 10:50 PM
It's cheaper that steel! No fires yet

JoeHarris
04-03-2013, 02:14 PM
OK, so I'm getting the hang of this welding business and selling all of my possessions to afford the steel!

here are some images of the steel frame design so far:
833683378338
It consists of
1no. 6000 x 50 x 50 x 3mm SHS for the bed
2no. 6000 x 100 x 50 x 3mm RHS for the legs and cross members
1no. 6000 x 75 x 50 x 3mm RHS for the bearings and ball screws to mount to
1no. 6000 x 60 x 6mm flat for the plates and cross bracing
1no. 3000 x 60 x 6mm flat for the plates and cross bracing
1no. 1500 x 60 x 60 x 6 RSA for the brackets

Now all seems fine till I cost the sucker up and it comes in at (Internet price) 460 - a little over what I was hoping!

Now I reckon I can get this down by going to a local supplier, but not by a lot.

The other idea is to take the 100 x 50 x 3 box section down to 50 x 50 x 4 which will save about 60. I cant think of any other ideas. Do you think the loss in section size will be offset by the increased weight?

maybe i'm over designing the whole thing and it could all come down in size?? I know Jazz has mentioned somewhere that skimping on the frame is a bad idea due to resonance issues - but how far do you go? I mean I'm not casting it as one lump of iron!

One other thing. I am welding plates onto the end of most box sections and then bolting together so as to allow for a bit of adjustment, and I'm not planning on welding the RHS's that take the bearings / ball screws so as to limit heat distortion. Trust this is a smart move?!

Cheers

Joe

Wobblycogs
04-03-2013, 02:40 PM
You're frame is broadly the same design as mine and even partially built I can tell mine will be strong enough so you shouldn't have any problems.

In terms of strength I'd drop it down to 50x50x4 to save some cost. If you look around here you'll find a spreadsheet that does gantry deflection calculations. The span on the the x-rails (between leg and centre support) is the same sort of problem, if you plug in the details of your steel you'll find that the deflection is tiny (<1um I'd guess) and it'll also be tiny for 50x50x4. If anything that spreadsheet will over estimate too since the ends of the rail will be welded into place.

The only thing I'd say about 50x50x4 is that is doesn't give you a lot of room to mount the rails on. I wish I'd gone for 60x60x4 now but that's the great thing about hindsight.

From someone that has tried to bolt together his machine to someone about to try, don't bother. It's very slow and you don't get any meaningful adjustment at the end. In SketchUp it's really easy to place a bolt hole and give yourself a perfect 1mm of play so you have some adjustment. In real life you won't be able to work to the sort of accuracy necessary unless you have a full on machine shop in which case you'd be better of just buying a CNC. Like you I'm going to bolt the main x-rail on but pretty much everything else will now be welded together (I've got the welder I'm now just waiting for a workshop that has sufficient power). I'm not entirely convinced that bolting on the x-axis rail will help all that much in preventing distortion, I've tried welding some of my 50x50x4 and I couldn't spot any distortion. What bolting will help with is shimming if you find your two rails aren't quite parallel in the z dimension.

D.C.
04-03-2013, 02:43 PM
I just priced up similar at fhbrundle in birmingham and it came to 350 inc vat and delivery. But bear in mind that I think they only sell in 7.5mtr lengths so I was ordering quite a bit more steel than you have listed.

Steel Sections from stock to meet any fabrication specifications - F H Brundle (http://www.fhbrundle.co.uk/groups/30__Steel_Sections)

Not to sound to nuts, but have you considered filling the beams with some, erm, epoxy...?

You could also save a bit of money by dropping down to 80x40 & 40x40 instead of 100x50 & 50x50, just make sure you can still mount your rails.

D.C.
04-03-2013, 02:52 PM
Just tried a different basket,

3 lots of 7.5mtr 80x40x3 = 146
1 lots of 7.5mtr 40x40x3 = 30
1 lots of 6.1mtr 60x60x6 angle = 40
1 lots of 6.1mtr 60x6 flat = 21

Total inc & delivery = 282

If you can drop down to 80x40/40x40 and redesign the diagonal bracing so that you use some flat and some equal angle for the bracing you should save a fair bit on what you thought.

JoeHarris
04-03-2013, 08:05 PM
Cheers guys, really helpful. I'll have a bit of a rethink! Must cost a bit to fill with epoxy right??

Iwant1
04-03-2013, 09:48 PM
Joe,

I too will be building a similar style frame to your, with lots of bolting. I think it means not only adjustment, not sure how much, but also allows me to do the welding outside then bring it in to fit together, manoeuvrability I mean. The only difference is I plan on using 90x45 extrusion just where the x rails rest. I think this is an easier method to fix profile rails onto. Not sure if it flatter, but we'll find out when the time comes, but I still do expect to file and sand till its 100% flat. Just don't want problems with the profile rails binding once everything is built.

From what I've read in the past, people use sand for filling in the hollow sections for dampening. Epoxy could be used for levelling out your 100x50mm RHS to provide a flat surface for your rails to rest on. Also could be used on the joints where you bolt the frame together like a thin shims to make sure everything ends up square and parallel. With this method you have to tighten your bolts just enough till the frame is where you want it, let the epoxy dry and harden fully, then tighten the bolts fully.

Cheers all for the heads up on types of cost involved.

Adil

D.C.
05-03-2013, 04:02 PM
Cheers guys, really helpful. I'll have a bit of a rethink! Must cost a bit to fill with epoxy right??

If you are using west system 105, it will cost about 100 for 5kg epoxy and 50 for 1kg hardener. Depending on how hardcore you want to be with the aggergates you will end up with a mix that contains anywhere from 7% (hardcore) to 20% (lazy git) epoxy/hardener. You will also want couple of calibrated pumps for 15 - 20.

Assuming you want to fill 1m of 80x40x3 steel box internal the volume is 0.002849 metres cubed (or about 2.8 litres of space). 6kgs of epoxy/hardener is about 4.5 litres so a 10% mix would get you 16m or a 20% mix would let you fill 8m. The total cost include the aggergates (if you can buy them in small enough quantities) would be about 200.

martin54
05-03-2013, 10:30 PM
Waste of money buying the pumps for something like this, couple of plastic measuring jugs from the supermarket will do the job, west systems is a 5 to 1 ratio & you would need a slow hardener. West systems is a good product but I would imagine a cheaper resin would do just as good a job for this sort of thing. Not sure about the process of filling a machine frame but generally speaking adding something like 403 or 404 fillers will aid. You can find a list of fillers & uses here. I generally use the 403 but that's more specific to work I do & not filling a machine frame.

Jonathan
05-03-2013, 10:43 PM
Waste of money buying the pumps for something like this, couple of plastic measuring jugs from the supermarket will do the job

I thought that...


West systems is a good product but I would imagine a cheaper resin would do just as good a job for this sort of thing.

I would have thought polyester resin would be fine since it's only filling the frame.

JoeHarris
05-03-2013, 11:29 PM
Waste of money buying the pumps for something like this, couple of plastic measuring jugs from the supermarket will do the job, west systems is a 5 to 1 ratio &amp; you would need a slow hardener. West systems is a good product but I would imagine a cheaper resin would do just as good a job for this sort of thing. Not sure about the process of filling a machine frame but generally speaking adding something like 403 or 404 fillers will aid. You can find a list of fillers &amp; uses here. I generally use the 403 but that's more specific to work I do &amp; not filling a machine frame.

Is it really necessary to start filling your frame with resin?! How much of a difference in finish are we talking for the extra expense and hassle?! My gantry will be ali extrusion in the L configuration btw... I don't want a terrible finish on my work at the end of all this but at the same time I'm not going to be machining parts for Breitling!

D.C.
06-03-2013, 01:07 AM
I would have thought polyester resin would be fine since it's only filling the frame.

Polyester isn't suitable because it shrinks too much apparently, I would refer you to the exact part of the epic thread on cnczone where that is discussed but I'm not reading that bloody thing again!


Is it really necessary to start filling your frame with resin?!

The whole point of being a cheapskate diy chappie is spending the least amount of money possible for the quality you want, if your machine is serving you great with steel box then it ain't broke so don't try and fix it. If you want better stiffness and vibration dampening to give better quality then it's an option open to you.

Swarfing
06-03-2013, 08:50 AM
If you want to make sure all the voids are filled then try using an orbital sander against the box to work like a vibro rod. Just put a bit at a time in and vibrate the hell out of it.

JAZZCNC
06-03-2013, 10:14 AM
I wouldn't bother with resin it's messy and expensive.!!. . . . . . If you need to dampen Just use kiln dried sand It's cheap and nothing works better at damping resonance.
Build in a drain hole has well a fill hole and you can easily remove when need to move machine around.

Jonathan
07-03-2013, 01:52 AM
Polyester isn't suitable because it shrinks too much apparently, I would refer you to the exact part of the epic thread on cnczone where that is discussed but I'm not reading that bloody thing again!

Surely that's because they're discussing using it for making bearing surfaces, where clearly the dimensional tolerances are critical. Does it really matter here if it shrinks a bit...

D.C.
07-03-2013, 02:22 AM
Surely that's because they're discussing using it for making bearing surfaces, where clearly the dimensional tolerances are critical. Does it really matter here if it shrinks a bit...

I'm not sure tbh, if you have a solid, shrunken lump inside of a steel box surely most of the vibration will just stay in the steel and not pass into the EG, the steel beam would also deform like normal steel until it made cotact with the EG beam?
This is why someone really needs to part with some cash and do some directly comparable real world tests...

JoeHarris
22-03-2013, 02:41 PM
8539

Revised 80x80x3 SHS frame - brings the cost down quite a bit. 6mm plate and/or welded connections...

CraftyGeek
08-08-2013, 04:23 PM
Just been going through the whole of your thread, its given me some good info for my design/build....where are you at with it now?

JoeHarris
09-08-2013, 08:42 AM
I have have had a set of cutting/drilling/tapping drawings done for the frame for ages but for one reason or another have not started building the frame yet. I have the mighty Rage 2 now so will be ordering the steel in the next week or so. I've also been collecting some of the other tools I'm going to need, got a precision 1m rule, couple of engineers squares, caliper etc etc

Really want to get on with it!

CraftyGeek
09-08-2013, 11:51 AM
Ah - I can imagine that takes a while to accumulate...my workshop has been getting more & more cluttered with that kind of stuff for the last couple of years :-p
Looking forward to seeing some progress ;-)

JoeHarris
13-08-2013, 06:50 PM
Just ordered me some steel... About time!

JoeHarris
30-08-2013, 02:02 AM
9906 big pile of steel.

JoeHarris
30-08-2013, 02:04 AM
9907big saw.

D-man
30-08-2013, 08:37 AM
Awesome. What short of price was that?

CraftyGeek
30-08-2013, 08:41 AM
What drill press is that lurking in the background?...looks incredibly similar to mine :-p

JoeHarris
30-08-2013, 02:37 PM
Awesome. What short of price was that?

The saw was just shy of 200 and the steel was 210 including delivery which I was really chuffed about, was expecting to pay quite a bit more considering the quantity!! Started cleaning it all up and marking out last night - feels like proper progress finally!

JoeHarris
30-08-2013, 02:39 PM
What drill press is that lurking in the background?...looks incredibly similar to mine :-p

It's an Axminster but I can't remember the model - small but pretty good so far only real limit is the minimum rpm is 500 - I'd like to be able to run it slower for some of the big holes I'm going to need...

CraftyGeek
30-08-2013, 03:44 PM
It's an Axminster but I can't remember the model - small but pretty good so far only real limit is the minimum rpm is 500

Thought so - that's what i've got...although I think i've got a lower model.
Yep - rpm is limiting...also now i've started drilling steel i'm finding it doesn't have as much torque i'd like (it stalls/gets stuck quite easily - mine only has a 150W motor...wondering if I can retro fit something with a bit more oomph in there...

JAZZCNC
30-08-2013, 04:06 PM
...also now i've started drilling steel i'm finding it doesn't have as much torque i'd like (it stalls/gets stuck quite easily - mine only has a 150W motor...

Buy some cutting paste when drilling steels makes quite a difference to ease of cutting, won't replace lack of power but does help some with lower power motors.

JoeHarris
31-08-2013, 12:16 AM
Thought so - that's what i've got...although I think i've got a lower model.
Yep - rpm is limiting...also now i've started drilling steel i'm finding it doesn't have as much torque i'd like (it stalls/gets stuck quite easily - mine only has a 150W motor...wondering if I can retro fit something with a bit more oomph in there...

99189919

Slightly meatier on mine - 370w. It's not the power that's the issue for me it's the speed - it looks like there is a hole for a third gear - photo - anyone know if you can retrofit them?

Wobblycogs
31-08-2013, 07:06 AM
That looks very familiar... There's a third pulley in mine which allows the drill to go down to really low speeds. The middle pulley is on a sort of offset arm so that it's free to move about when the belts are in different positions. With some work I think you could probably fabricate the necessary parts. Once the kids are awake (got to be quiet at the moment) I'll see if I can't get you a couple of photographs of the inside of mine.

Wobblycogs
31-08-2013, 12:05 PM
As promised a couple of photos. I pulled the middle pulley out so you can get an idea of size.

99209921

Sorry for the shocking photo quality it's a bit dark in what passes for my workshop.

JoeHarris
01-09-2013, 09:27 AM
Cheers,
yeah that is just what I want - from what I can see though those bits and pieces are not available as accessories - I can't even find anything on eBay.

Don't see how I could make them without a lathe...

Wobblycogs
01-09-2013, 12:05 PM
I'm sure someone with more metal working experience than me will say this won't work but I see 4 parts in that pulley assembly. The pulley, which you would have to buy and the arm which you'd make from three pieces. I reckon you could but bar of the right diameter for the pulley and the machine holes then you just need to fabricate the arm. A scrap of steel, hacksaw and file would probably be enough. Drill and tap the bar and bolt it to the arm, a weld would be better if you have the facilities. Would be an interesting little project.

JoeHarris
04-09-2013, 11:34 PM
Went and had a chat with chap at rotagrip (awesome collection of machines there) and seems my drill speed issue is only going to be solved by buying a better drill! Ah well.

On happier note, feels like this is now becoming a build log rather than a drawing log - pics of progress so far (marking and cutting.)

I am AMAZED by the rage2. 6mm plate and 80x80 box is child's play. Spend most of the evening sweeping up though!!

99759976

CraftyGeek
05-09-2013, 07:10 AM
I am AMAZED by the rage2. 6mm plate and 80x80 box is child's play.


I know - i'm amazed by mine as well...i've been chomping through 10mm flat bar without any issues.
What's even more surprising is the quality of cut. I got my steel yard to cut some of my steel to size for me on their large, fluid cooled automatic reciprocating saw thingummy...my cuts are smoother, more accurate & SQUARE in comparison to theirs...lesson learned :-p

mekanik
05-09-2013, 09:50 AM
Hi guys
Had a look @ that model, are you cutting steel with the TCT blade or using an abrasive disc ?

CraftyGeek
05-09-2013, 10:16 AM
Hi guys
Had a look @ that model, are you cutting steel with the TCT blade or using an abrasive disc ?

I've actually got the 255mm Rage 3 - just using the stock multipurpose blade that came with it.
I use that blade for most rough jobs & have a decent quality wood blade for more important diy jobs.
I've used it to cut wood, plastic, aluminium & steel - does a decent job on all of them.

There's a video on youtube of a guy in the USA demoing it cutting through loads of different materials & comments on cutting finish & material temperatures etc Its worth a look if you're considering getting one.

JoeHarris
10-10-2013, 08:13 PM
10403104041040510406

Slow but steady progress - grabbing an hour here and there...

JoeHarris
09-11-2013, 04:35 PM
106211062210623
First parts drilled, tapped (and fit!) decided to weld plates to the inside of the box sections to increase thickness for tapping... Thanks Jazz for the idea

JoeHarris
22-01-2014, 11:50 PM
113491135011351

JoeHarris
24-01-2014, 11:03 PM
A word of advice to anyone buying a tap wrench - don't buy a cheap eBay jobby like I did - they are crap. Just ordered the real deal from starrett... :) same applies with centre punches - buy a starrett you won't regret it!

JoeHarris
11-02-2014, 12:34 AM
Hello. I have decided to catalogue some of the build logs i have found inspirational over the last couple of years in a place where I can find them easily !! Not an exhaustive list but if you are building then take a look at these... Please add to the list if there are others you have found useful. There is nothing like reading build logs to keep you going with (and changing!) your own build so Cheers to all of you for posting them!

Adcnc's build log

http://www.mycncuk.com/forums/gantry-router-build-logs/1638-my-first-attempt-cnc.html

Jazz turns the beast on its side!

http://www.mycncuk.com/forums/showpost.php?p=28039

Michael's build

http://www.mycncuk.com/forums/gantry-router-build-logs/3661-1st-build-second-machine-4.html

Bruce's build

http://www.mycncuk.com/forums/showpost.php?p=37447

HiltonSteve first build log I read on mycnc I think

http://www.mycncuk.com/forums/showpost.php?p=17636

Jonathan's first build inc. rotating ballnuts

http://www.mycncuk.com/forums/showpost.php?p=19278

Matt (aka creaky)'s build

http://www.mycncuk.com/forums/showpost.php?p=42976

Matt's second super-fast build

http://www.mycncuk.com/forums/showpost.php?p=48953

Jonathan's "sufficiently strong machine !" (Needs no intro)

http://www.mycncuk.com/forums/showpost.php?p=49294

Adil - one to watch...

http://www.mycncuk.com/forums/showpost.php?p=42635

Silyavski - one to watch...

http://www.mycncuk.com/forums/showpost.php?p=54769

(http://www.mycncuk.com/forums/showpost.php?p=54769)EddyCurrent - one to watch...

(http://www.mycncuk.com/forums/showpost.php?p=54769)http://www.mycncuk.com/forums/gantry-router-build-logs/6565-ready-steady-eddy.html (http://www.mycncuk.com/forums/showpost.php?p=54769)




(http://www.mycncuk.com/forums/showpost.php?p=54769)

JoeHarris
11-02-2014, 12:49 AM
Oh and another leg done.1156511566

JoeHarris
08-05-2014, 10:54 PM
Garage finally free of bits of bathroom, so I decide to get the big sheet of steel I've got for welding on up onto my bench. I added a couple of extra legs for extra support, managed to get the thing up onto 3 bricks, but my 1st and only attempt to lift it onto the bench did not go well! Think I need some friends!!12355

JoeHarris
09-05-2014, 12:19 AM
Take two!12359

JoeHarris
21-05-2014, 12:13 AM
12411 polished up and vice mounted!

12412 nice legs!

JoeHarris
22-05-2014, 09:03 PM
I have just realised that I started this build log just over two years ago and I still have not finished the frame! I knew it was going to be slow going but I had not appreciated the time it takes to build one of these things. So anyone with a busy job and young family just starting out on a project like mine... Don't expect to have it done in a couple if months!!! Pretty much everything I have had to learn from scratch and it has been a lot of fun so far so please don't let me put you off. Just taking a LONG time!

njhussey
22-05-2014, 11:22 PM
I started mine in 2010 and have only just got the frame welded up so you're doing better than me!!!

JoeHarris
04-10-2014, 01:01 AM
13528 13529
13531

Making some progress on the frame. Welding at long last!

And another distraction! There goes the money saved for the next batch of parts... 13532 fun though!

irving2008
04-10-2014, 06:15 AM
Ohh, looks like a classic Drummond model B circa 1920. What's the condition like?

JoeHarris
04-10-2014, 09:42 AM
Sure is! Pretty good condition, bed ok, spindle running true so I think bearings are ok. Looks like the back gear has experienced some pretty severe torque at some point as there is a broken tooth on the gear /corresponding broken tooth on the spindle and a twisted back-gear shaft. So my first project is going to be to make a new one, figure one missing tooth should be ok but spares are pretty easy to come by if i need them. I have an m type topside coming too with a Norman toolpost. The original topslide has had a bit of a dodgy welded repair job on the ways which was bothering me! All in all pleased with it for a first lathe and I love the look of it with it's curved headstock brace...

irving2008
04-10-2014, 10:20 PM
Well the model B was never sold commercially, they were all intended for the Navy to be used on-board ships, but often unused ones found their way out :) so they can often be in good nick. The overarm bracing does look cool but doesn't really do much for the headstock stiffness.

Gears are 14DP 14.5 so can be found quite easily. Did you get a full set of change wheels inc the 63tooth to do metric screw cutting?

What's the centres distance? It looks quite long.

JoeHarris
07-10-2014, 12:23 AM
I will try and remember to have a look tomorrow Irving - just come in from another session welding and can't be bothered to get cold again!13547

JoeHarris
18-11-2014, 02:30 PM
13878

Further frame progress - pretty well tacked up now. I will take it apart into sections to fully weld the joints and add the gussets. This was one of the reasons for bolting large sections together - it avoids too many awkward welding positions...

njhussey
18-11-2014, 05:01 PM
Joe that looks like a work of art :D

D-man
18-11-2014, 05:38 PM
Nice work Joe!..... wana do an 8x4 lol

JoeHarris
18-11-2014, 05:50 PM
I really do! But it has taken nearly 18months to get this far so......

D-man
18-11-2014, 06:07 PM
Oh I see, Oh well guess i will have to dig deep and find some patients ha *Subscribed!

JoeHarris
19-02-2015, 12:48 AM
1468414685 frame painted up. Needs X rail support beams next then frame is done.

njhussey
19-02-2015, 10:17 AM
Looking good Joe!

JoeHarris
15-03-2015, 12:50 AM
1487214873

:)

GEOFFREY
15-03-2015, 10:54 AM
That looks great - very sturdy and neat. Great stuff. G.

JAZZCNC
15-03-2015, 12:37 PM
Looking Good Joe but your gonner need more room buddy.!! . . . . It's good as well you have a before and after shot of how clean the room looks because it never look like that again after those chips start flying. . .Lol . . . . Get cracking need to See Video movement next.!!!

JoeHarris
15-03-2015, 01:53 PM
Looking Good Joe but your gonner need more room buddy.!! . . . . It's good as well you have a before and after shot of how clean the room looks because it never look like that again after those chips start flying. . .Lol . . . . Get cracking need to See Video movement next.!!!

I know! Space is tight and I have to try and keep it clear as our freezers in the garage and the rest of the family object to aluminium chips in their feet for some reason?!
It is taking an age but slow and steady it will be finished eventually!!! Cheers guys.

njhussey
15-03-2015, 02:21 PM
Looking good Joe, keep it slow and steady that way you'll not make any mistakes!

JoeHarris
15-03-2015, 02:53 PM
Looking good Joe, keep it slow and steady that way you'll not make any mistakes!

I don't know - think I just make them more slowly!!

JoeHarris
17-06-2015, 07:02 PM
http://www.mycncuk.com/attachment.php?attachmentid=15577&stc=1http://www.mycncuk.com/attachment.php?attachmentid=15578&stc=1http://www.mycncuk.com/attachment.php?attachmentid=15579&stc=1Some stills from my updated model...

routercnc
17-06-2015, 09:21 PM
Hi Joe,

Coming together nicely now. Is there any reason on the gantry for putting the X axis bearings out the back and the spindle hanging out the front? Normally you would put a bearing near the spindle axis to give more support. Do you need to cut right over the edge of the machine?

Not saying it won't work as drawn because it will, just that it could be a little better if there was no reason for the bearings positioning as drawn.

JoeHarris
20-06-2015, 02:00 PM
The reason was clashes in fixings. I am going to make some changes to that area anyway to bring the ball screw mounts to the outside of the gantry sides, so I'll try and take on your advice too... Cheers

voyager1972
21-06-2015, 07:43 PM
Looks a very nice setup..
I am interested in a similar style'll of machine capable after taking an 8*4 sheet material....would be gratefully for some advice on material suppliers ,like aluminium extrusion and bearing guides ect.

JoeHarris
23-08-2015, 04:45 PM
Looks a very nice setup..
I am interested in a similar style'll of machine capable after taking an 8*4 sheet material....would be gratefully for some advice on material suppliers ,like aluminium extrusion and bearing guides ect.

Apologies for the late reply - bearings and rails BST Automation in China. ( Aliexpress) aluminium extrusion Motodis (Germany) ball screws Chai (eBay) steel from a local merchant...

JoeHarris
03-09-2015, 01:04 AM
https://vimeo.com/138142743
Has anyone come across this issue and know what is causing it. One of my carriages is very juddery and stiff - particularly in one direction...

njhussey
03-09-2015, 09:55 AM
I had that problem on one of mine when I dropped my balls....have you taken it off and looked to see if they're all there? Not sure why it affects one direction more than another....plenty of grease in it?

JoeHarris
03-09-2015, 10:01 AM
I should add that the seller I bought them off is sending a new one so not too worried - just wondered. Yes all greased up and no dropped balls!!

JoeHarris
03-09-2015, 10:02 AM
Not sure how many balls there should be in there to be honest.

JoeHarris
17-09-2015, 12:59 AM
In case anyone is looking for help fixing two pieces of extrusion together... 1605916059 10mm transfer punch to mark then centre punch to get holes centred. 16060 insert 10x25mm aluminium and shim16061 (not the traditional Guinness I know!) 1606216063 drill holes on the drill press 16065put it all together! 1606616067160681606916070

JoeHarris
18-09-2015, 11:44 PM
Almost finished jig for router-milling the gantry ends...1608816089

Tenson
19-09-2015, 12:14 AM
Sorry for the high-jack but I've been wondering about best gantry geometry recently. I half remember a thread comparing some different alignments with simulation of force in various directions. Do I remember right? I kind of remember this 'L' shape being best, but I'd like to re-cap.

JoeHarris
19-09-2015, 12:17 AM
It depends who you listen to! This method got my vote. But some people like to sandwich the ball screw between two sections of extrusion to bring the screw closer to the stuff it's moving. I like the fact the this method protects the screw somewhat. Very strong from what I can tell!

JAZZCNC
19-09-2015, 12:33 AM
Sorry for the high-jack but I've been wondering about best gantry geometry recently. I half remember a thread comparing some different alignments with simulation of force in various directions. Do I remember right? I kind of remember this 'L' shape being best, but I'd like to re-cap.

Not sure about the Simulation thing but I can tell you from experience having built many many machines using this "L" design it works perfectly for Wood routers and is very stiff.!
If your wanting semi milling machine stiffness then you'll maybe want to go with something a little stiffer and heavier. But for wood routers and light Aluminium work then it's plenty strong enough.!

Tenson
19-09-2015, 12:47 AM
Thanks Jazz, I was not thinking so much about the specific build as the geometry. You could put those two sections in a kind of '=' alignment or the 'L' shape used here. The first is probably better to resist front to back force but the second will perhaps have a better mix of up/down and front/back strength. If I built mine again I'd use large and thick steel section with end plates to affix.

I've also been thinking about best placement of the X axis (sideways) rails. I mean say (for sake of simplicity) you had a square gantry section. You could put rails on the top and bottom so they are opposing but then you need to create the Z axis as a kind of box to wrap around the gantry. The joints in that 'box' will be a point of weakness. On the other hand you could place the rails on the front face of the gantry and the Z axis plate can attach directly. Which is better? If you have great rails and bearings with zero play I imagine the second option, but no rails are perfect.

This will help explain what I mean, I hope.

http://s10.postimg.org/bf8hrlxm1/Gantry.jpg
This would make building CNC machines easier! - https://www.youtube.com/watch?v=pevgkx69j8o

Blackrat
19-09-2015, 10:25 AM
first option is quite difficult , my first build i did that ...

second option is way easier, especially if you use epoxy to level.

both my machines are steel welded . i guess using aluminum extruded will be easier for option 1

njhussey
19-09-2015, 01:18 PM
The first option is, as Jazz says, like a cornflake packet with the ends removed, just think how stiff that is! If you move the rails nearer the face you'll reduce the flop. I've done this on my gantry and it seems plenty stiff to me. Second option puts the router further out from the face. Both will work...

JAZZCNC
19-09-2015, 02:37 PM
The first option is, as Jazz says, like a cornflake packet with the ends removed, just think how stiff that is! If you move the rails nearer the face you'll reduce the flop. I've done this on my gantry and it seems plenty stiff to me. Second option puts the router further out from the face. Both will work...

Hold on here Lads this is Jo's thread so lets not hi-jack it hey.!! . . . . Suggest Start a new thread if required.!

Edit: Used your Quote Neil to high light point being last post on it not having a go at you mate. . :thumsup:

JoeHarris
19-09-2015, 11:32 PM
I don't mind the highjack interesting to read... Although I think the cornflake packet is where I'm headed! Jazz when you build your L gantry machines which option do you use? I thought I had seen you use rails top and bottom?

JAZZCNC
19-09-2015, 11:40 PM
I don't mind the highjack interesting to read... Although I think the cornflake packet is where I'm headed! Jazz when you build your L gantry machines which option do you use? I thought I had seen you use rails top and bottom?

Yes top and Bottom like this.

16100

Or This without tall sides.

16101

Tenson
19-09-2015, 11:49 PM
Hi Jazz,

So your small design above doesn't have a back piece on the Z axis assembly, but has side panels to give strength to the joints?

Looking again at rail location, would one rail on the bottom and one on the front be a good combination? Like this machine:


http://www.mycncuk.com/attachment.php?attachmentid=16103&stc=1

JAZZCNC
20-09-2015, 12:05 AM
Hi Jazz,

So your small design above doesn't have a back piece on the Z axis assembly, but has side panels to give strength to the joints?

Yes doesn't have back piece because it add's no strength just weight. The Panels you refer to are not for strength, thou they do slightly add some. It's purely a Cover to protect the whole Z axis assembly from dust and crap. It's very affective and neat.

The 90Deg joints are perfectly strong enough for any type of work upto and including machining aluminium.!

Regards rail location then it's a personal choice and also partly machine design related. Me personally I prefer to keep things stout and compact and gain maximum real estate. But if you need clearence for ballscrews etc at the front then putting rails on the front allows this and keeps it stiff. Each way has it's own Plus's & minus's. Both work equally well so take your pick.!!

JoeHarris
23-12-2015, 10:27 PM
Bit of an update. I've bought some plate and started to make some of the aluminium parts. Tried out my new counter bores too which were an absolute joy to use [emoji3]1689616897168981689916900

JoeHarris
23-12-2015, 10:30 PM
Oh and the model has changed again too! 1690116902

Clive S
24-12-2015, 12:33 AM
Looking good Joe coming along nicely

Tenson
24-12-2015, 01:40 AM
How do the two gantry profile sections affix together? I can see a ali bar in the T-slot but I'm not sure still.

JoeHarris
24-12-2015, 02:28 PM
Tenson- I tried to explain this in a previous post on this log - http://www.mycncuk.com/showpost.php?p=72346

JoeHarris
29-12-2015, 12:03 AM
16927milling aluminium with a router was fairly successful. More successful than I expected anyway... 1692816929169301693116932 just need to wait for my m12 counterbore and some m12 capscrews of a sensible length to arrive! and the gantry will be well on the way.

Clive S
29-12-2015, 12:28 AM
Just goes to show what can be done with simple tools, very nice

JAZZCNC
29-12-2015, 01:06 AM
Well done Joe. My first machine was hand cut with router so know how scary cutting ali by hand is for first time. . :thumsup:

TonyD
30-12-2015, 06:39 AM
Looking good Joe. :)

routercnc
30-12-2015, 05:01 PM
Great work Joe. Solid looking machine in the making . . .

:thumsup:

JoeHarris
02-01-2016, 02:00 AM
Other side cut... Wishing I had more space! 17033

njhussey
02-01-2016, 09:56 AM
Looking good Joe, coming on nicely!

petercoulthard
07-01-2016, 01:56 PM
Other side cut... Wishing I had more space! 17033

Hi Joe,

I have read all of your build and all of the helpful comments with great interest. You are building more or less exactly the machine that I have pondered about for a long time.
Do you have an idea of what the final cost will be when done?
Thanks
Pete

JoeHarris
07-01-2016, 08:44 PM
A lot! I think the build will be the around 1500 to 2k? But to be honest I've kind of lost track! The biggest cost so far by miles is all the tools I have bought for the project. I keep realising I need another bit of equipment. From drill bits to taps and tap wrenches, centre punches, transfer punches, counterbores, a router, drill press, cut off saw, band saw, lathe, welder, callipers, dial indicator, computer, software etc etc the list goes on - so who knows. What I do know is I've learnt a huge amount and loved the experience so far... Look forward to seeing your build.

JoeHarris
07-01-2016, 08:49 PM
17145 on the subject of buying stuff my new m12 counterbore has arrived. Time to finish the gantry. 17146

njhussey
07-01-2016, 09:17 PM
I love the sight of shiny Aluminium.....really looking forward to seeing this move Joe :thumsup:

routercnc
07-01-2016, 10:22 PM
Fabulous job Joe !

Even more so that you are making it by 'hand' without another cnc machine to help cut bits. Keep ticking away at it and before you know it you'll will be rewarded with a really solid machine.

trigus
10-01-2016, 05:52 PM
Hello,

I'm very exiting your cnc design. Maybe you have video how cnc works? maybe can get drawings from you?

JoeHarris
13-01-2016, 08:59 PM
Hello,

I'm very exiting your cnc design. Maybe you have video how cnc works? maybe can get drawings from you?

Hello, whilst I'm not at all opposed to sharing, in my experience the design process is essential if you want to understand what you are building and why. I would encourage you to read a lot on this site and others then get drawing!

JoeHarris
19-01-2016, 10:04 AM
17272

I had decided to go with slaved motors but I really want to use a CSMIO/IP-M Motion Controller and they don't like slaved motors. Early on I had toyed with a belt drive and after reading posts on biketrialdave's build log I'm heading back that way I think. The belt will need to be made as it is over the size limit for standard belts but the cost of a custom one does not seem extortionate! The basic idea is as the image above... which would not require much modification from the existing setup. As usual, any comments are gratefully received!

routercnc
19-01-2016, 01:23 PM
17272

I had decided to go with slaved motors but I really want to use a CSMIO/IP-M Motion Controller and they don't like slaved motors. Early on I had toyed with a belt drive and after reading posts on biketrialdave's build log I'm heading back that way I think. The belt will need to be made as it is over the size limit for standard belts but the cost of a custom one does not seem extortionate! The basic idea is as the image above... which would not require much modification from the existing setup. As usual, any comments are gratefully received!

Hi Joe,
I wonder if that long unsupported run of belt would flap and vibrate around. Do you think it would be in perfect syncrony on each ballscrew? Also, a single motor would need to be more powerful than 2 singles.

On my new machine (not CSMIO) I am going with 2 motors and 2 short belts, then one long slave belt between them which mostly does nothing unless there is a problem. Would CSMIO let you feed step/dir signals into 2 drives? Is that acceptable? I know you can't 'slave' home in the traditional sense with that suggestion, but with a link belt you wouldn't have to.

JoeHarris
19-01-2016, 02:11 PM
I was going to up the motor to a nema 34 12nm beast. This is a similar size belt to Dean's first machine I think? He had an idler part way along not at one end. If I get flapping I could add one in the same way. I understood that the ip-m just did not allow proper slaving...17273

JoeHarris
19-01-2016, 02:15 PM
Hi Joe,

Sorry not replyed to some of your previous post's where you asked me directly, I've had eye trouble so time on computer has been limited hence me not being around much.!

Others have answered the belt Q's regards width, pitch etc but there are things you need to be made aware about with this size machine.?
One of the things I found when I built my machine was that long belts where not available in 5 x 15mm HTD so depending on the X axis screw centres you may have the same trouble.?
The X screw centre's on my machine are 1300mm using 30T pulleys so needed belt length over 2750mm the longest HTD 5mm pitch 15mm wide I could find was around 2400-2500mm.
The way I got around it was to have them special made costing around 20 each. I bought 2 keeping one for spare, that was over 3yrs ago and I've only recently swapped for the spare and that was because I left a pulley lose after changing ratios from 1:2 to 1:1 for high resolution job and it fell off killing the belt in the process.!!

Regards mounting pulleys you will need the ballscrew ends machining longer than standard so the shaft goes all the way thru the pulley giving better purchase for the grub screws. Also grind a small flat on the shaft for the grub screw to grip and stop the pulley spinning.
Regards idlers and tension then You don't need lots of tension on the belt and infact if you put them under too much tension they wear quicker and it also puts tension on the ballscrew bearings and if Ott can cause binding and possible missed steps.? Just enough tension to stop the belts flapping around and jumping teeth is all thats needed and lightly tensioned idlers is all thats required. (I just use 2 bearings with large penny repair washers for guides)

I'm posting the pics of my well used setup and While my setup looks ugly and is roughly thrown together it's simple, works very very good and accurate with high reliabilty even thou I run it in some of the worst conditions for running belts.!!
I dont have any guards or shields, the machine mostly 98% of time cuts Aluminium with chips flying every where and it has never failed or lost position either thru skipped teeth or missed steps. While It's capable of max rapids around 11mtr/min with 5mm pitch screw 1:2 ratio(effective 10mm pitch) 6Nm Nema 34 motor running 75Vdc I detune it to 7mtr/min which is more than enough for my needs and also why It's NEVER, NOT WOUNCE missed steps or lost position or sync under cutting conditions or rapid movement.

To give you an idea of the resolution and what 1:2(10mm pitch) belts can achive then I've attached the Aztec calender pic with a link to video see the detail better.

Hope this helps and inspires.!

http://www.youtube.com/watch?v=wjDvimSdH8M&feature=youtu.be

59505951

JAZZCNC
19-01-2016, 04:56 PM
Hi Joe,
I wonder if that long unsupported run of belt would flap and vibrate around. Do you think it would be in perfect syncrony on each ballscrew? Also, a single motor would need to be more powerful than 2 singles.

Yes and No. Yes it needs a some support in the middle to stop flap. Does it keep perfect sync.? Yes it does.


On my new machine (not CSMIO) I am going with 2 motors and 2 short belts, then one long slave belt between them which mostly does nothing unless there is a problem.

Not so sure that will work has good you expect.? While in theory it will help keep screws in sync I'm not sure about the conflicts you might get if one motor starts missing steps. You'll have one motor fighting the other and because the Motors are connected directly to the screw I think you'll still get racking because the motors torque will force racking or affect the other motor and cause stalling etc.?
Also Don't see the point in taking the conflict risks when you still have the same belt setup.?

Edit: Then you have the affect of extra inertia of 4 pulleys on screws. It will affect performance.!

One thing for sure if you do this then make sure you have good drives because it will do funky things to the resonance and the drives will need to able to deal with it.!


Would CSMIO let you feed step/dir signals into 2 drives? Is that acceptable? I know you can't 'slave' home in the traditional sense with that suggestion, but with a link belt you wouldn't have to.

Bad idea with any controller but this isn't needed anyway the IP-M does allow slaving just doesn't independantly home each Axis.


I was going to up the motor to a nema 34 12nm beast. This is a similar size belt to Dean's first machine I think? He had an idler part way along not at one end. If I get flapping I could add one in the same way. I understood that the ip-m just did not allow proper slaving...

12Nm is way to Big Joe and will affect performance. 6 or 8Nm will be more than enough. Try to find motor with lowest inductance possible and use plenty of volts.

JoeHarris
07-02-2016, 04:57 PM
17540

The revised plan for the twin ball screws is to drive them from one motor with a long belt as shown in the image. The plan is two use two idler pulleys one of which will be fixed. I have been advised by one of the guys at beltingonline to support the long length of belt on sheets of UHMWPE which will not wear and is self lubricating. I will fix this to some lengths of steel angle I have left over. I should get the recommended 5 tooth engagement on all pulleys. I have allowed long enough slots for the motor mounts to use a smaller pulley if i want to change to 1:1 ratio. What do you think?

njhussey
07-02-2016, 06:28 PM
Joe, I'd put a plate over the square steel section your rails are moumted on, move the top pulley to the right and move the other pulley next to it. That way you'll have more teeth in contact with the ball screw pulley.

JoeHarris
07-02-2016, 08:31 PM
Joe, I'd put a plate over the square steel section your rails are moumted on, move the top pulley to the right and move the other pulley next to it. That way you'll have more teeth in contact with the ball screw pulley.

Yeah that's quite a nice idea. I think I might be too tight for space to get a good depth to tap for the idlers. I could certainly pull the lower left one up though which will improve things. This was a quick and dirty to test. I still need to draw a nema 34 as this is still based on the smaller nema 23 frame. Going from 56 to 86mm will change the setting out quite a bit...

Also any ideas why the SY85STH118-6004B Nema 34 Stepper motor from Zapp costs 94 and the cnc4you 86HS115-4208 8.7Nm Nema 34 Stepper Motor costs 71? Same size and torque and Inductance is the same...

JoeHarris
08-02-2016, 03:39 PM
1754917548
More or less complete design for the single motor, long belt method.
The idlers are both fixed and made from standard skate bearings spaced in the middle with a washer and edged with two penny washers to provide flanges - these will be mounted on a M8x40 bolt taped into the aluminum plate and stood off with a stack of washers. I can adjust the height of the whole motor assembly if necessary and fine adjustment can be made by raising or lowering the motor on 10mm slotted mounts, this was the max I could achieve with the large circular projection (which I assume houses the bearings) at the center of the motor.
17550
Both lengths of the long belt (top and bottom) are supported on UHMWPE (blue stips on the image below) which will be bolted down to steel angle which in turn will be welded or bolted to the frame with strips of 90x6mm flat bar. This support framework can then double up as the framework for a belt cover.

17547

The motor this is all based on is the cnc4you 86HS115-4208 8.7Nm Nema 34 Stepper Motor as highlighted on the data sheet below:

17551

njhussey
08-02-2016, 03:49 PM
I'd still put the top idler on the end of the square section (with a suitable thick plate welded/bolted in) and move the lower idler to the first idler's position.....:whistle:

JoeHarris
08-02-2016, 04:00 PM
I'd still put the top idler on the end of the square section (with a suitable thick plate welded/bolted in) and move the lower idler to the first idler's position.....:whistle:

Like the blue lines in this?: 17552

JoeHarris
08-02-2016, 04:02 PM
I like the idea but it's a pain to implement. I only have a few mm of space: 17553

njhussey
08-02-2016, 04:04 PM
Like this....excuse the freehand scribble!!

17554

Edit...Hah just seen the lines you drew....need to open my eyes!! Yes like that, will give much more teeth in contact, I know 5 is the min but I always think the more the merrier!!

JoeHarris
08-02-2016, 04:06 PM
[QUOTE=njhussey;76714]Like this....excuse the freehand scribble!!

Yes, sorry that's what the really faint blue lines were supposed to show!!!

JoeHarris
08-02-2016, 04:08 PM
I'm still getting the best part of 7 teeth engaged and 5 fully. According to Jonathan this should be sufficient. I'll have a think...🤔 as always - appreciate the critique even if it does mean more redrawing (again and again!!)

njhussey
08-02-2016, 04:12 PM
"should be sufficient."

Hmmmmm.......

JoeHarris
08-02-2016, 04:13 PM
Hmmmmm.......

Haha like your confidence

njhussey
08-02-2016, 04:17 PM
17555

That's how I've bodged mine in, at some stage I'll design a neat back plate and use the machine to cut it.....a bit Heath Robinson, but it works :thumsup:

JoeHarris
09-02-2016, 06:19 PM
1756117562If at first you don't succeed... be glad you modeled it first!

Lee Roberts
09-02-2016, 09:32 PM
That looks loads better Joe n1!

JoeHarris
09-02-2016, 10:43 PM
Cheers Lee!

njhussey
09-02-2016, 10:54 PM
That looks good Joe :)

Clive S
09-02-2016, 11:01 PM
New you would get there in the end Joe its tons better now:applouse:

JAZZCNC
10-02-2016, 10:12 AM
That's it Joe.:thumsup:

JoeHarris
10-02-2016, 10:17 AM
Cheers guys. When measuring the belt to order a bespoke length, do you measure one side or the centreline or what? Won't make a big difference I guess but if there is a right way I'd like to know.

JAZZCNC
10-02-2016, 10:54 AM
You build it then you get a piece of string and rap around pulleys and take to belt place and say I want one that long.!!:encouragement: (or then measure it's length.)

JoeHarris
10-02-2016, 11:26 AM
You build it then you get a piece of string and rap around pulleys and take to belt place and say I want one that long.!!:encouragement: (or then measure it's length.)

Ha ha. Love it. Yes ok it's not like me to over complicate things!

JoeHarris
05-03-2016, 12:53 AM
Z axis progress pictures. 17826178271782817829

Clive S
05-03-2016, 09:02 AM
Very nice as always Joe. Great idea on the spacer plates to save pocketing the ball screw BK mounts although it does push the spindle further out slightly. :thumsup:

voyager1972
29-03-2016, 10:08 PM
hopefully be starting my own build shortly ,capable of holding an 8*4 sheet.,,,,,,thinking of going with rack and pinion,,,,i am looking on the net for extrusion suppliers in the uk,,,does anyone have any recomendations on material suppliers..i am located in n.ireland.

Clive S
30-03-2016, 12:32 AM
hopefully be starting my own build shortly ,capable of holding an 8*4 sheet.,,,,,,thinking of going with rack and pinion,,,,i am looking on the net for extrusion suppliers in the uk,,,does anyone have any recomendations on material suppliers..i am located in n.ireland.Hi and welcome to the forum it would be better to start your own thread so as to keep all the questions you might have in one place.
Have you built a machine before? and have you decided what you need to cut?
Why not put a design up of what you would like to do. Good luck with the build.

JoeHarris
02-05-2016, 12:10 AM
I have finally levelled the frame as best I can - in its "final" position. I decided to tack weld the beams which will support the x rails (now I know they are as parallel as they ever will be) prior to pouring the epoxy and most significantly I have started to make the mdf channels in which to pour it.
I still need to grind the mill scale of the top surface and for the weather to warm up! 18353

JoeHarris
02-05-2016, 12:16 AM
Btw I have decided on 1no 30mm wide bridge and the channels for the rails will be 40mm wide (for 20mm rails) I hope this will be wide enough to avoid meniscus problems - I'm trying to get the most out of my tin of west system!

njhussey
02-05-2016, 12:33 AM
Watch for shrinkage at the ends of the rails, mine were slightly lower at the home ends...dunno why! Also double and triple check the seal between the MDF moat and your rails, leaks are a bugger to stop! If possible line the MDF with packing tape as it'll make getting them off so much easier...much less work with a file :)

JoeHarris
02-05-2016, 12:36 AM
Thanks for the tips!

Clive S
02-05-2016, 09:06 AM
Joe I did not have any shrink problems at the ends on mine but do put the effort in to stop any leaks you will be surprised how easy it is to get one, a small bead of silicone is the key

Neale
02-05-2016, 09:29 AM
I sealed my moats by running a small amount of epoxy along the gap first. Small amount and it doesn't run through but will cure in the gap and stop it leaking when the full depth goes in a day or two later.

voyager1972
02-05-2016, 11:17 AM
been looking at nema 34 stepper motors online,,,,,would they be suitable ?,,,,,i plan to be machining sheet material like mdf,,,melamine,,,oak and ash ect.. also i see the motors are avalable with differant holding torque......would the higher values be advisable.

Clive S
02-05-2016, 12:48 PM
been looking at nema 34 stepper motors online,,,,,would they be suitable ?,,,,,i plan to be machining sheet material like mdf,,,melamine,,,oak and ash ect.. also i see the motors are avalable with differant holding torque......would the higher values be advisable.It is impossible to say what size of motors you require without giving details re your machine. It might be a good idea to start your own build log to keep all the questions in one place.

JAZZCNC
02-05-2016, 08:24 PM
It is impossible to say what size of motors you require without giving details re your machine. It might be a good idea to start your own build log to keep all the questions in one place.

Clives 100% correct but it's also 95% chance they won't be suitable for few reasons. First reason high chance they will be high inductance motors which mean you'll need expensive high voltage drives.
Second reason is they'll be all wrong for your machine unless large or heavy load to move.

Jo be careful you have enough epoxy because it's proper ball ache if you run short. However I know 1ltr should be enough for machine your size so shouldn't have any trouble.
Really make sure you seal it well because it's amazing how epoxy finds leaks and they don't always appear instantly so keep checking and be ready to make repairs. Putty is handy stuff to seal quickly.

JoeHarris
04-05-2016, 12:24 PM
18386
Surface ground and scored with sandpaper. Dams almost complete... 18387

njhussey
04-05-2016, 12:42 PM
Looking good Joe....looking forward to seeing the pour!

JoeHarris
06-05-2016, 09:00 PM
Looking good Joe....looking forward to seeing the pour!

Me too. Bought some silicone sealant and found an oil radiator donor! Nearly ready...

njhussey
06-05-2016, 09:43 PM
Me too. Bought some silicone sealant and found an oil radiator donor! Nearly ready...
What's the oil radiator donating?

JoeHarris
07-05-2016, 12:35 AM
To heat my workshop... Someone is lending me a couple of them. A minimum of 16 deg C as a constant temp is recommended and West System state: "As the temperature drops, epoxy becomes proportionally thicker, reducing its ability to flow out." They also state that air bubbles are more of an issue at lower temperatures.

mekanik
07-05-2016, 11:00 AM
Hi Joe
If you have a vacuum pump you could knock up a degassing pot, i use an old pressure cooker.
Regards
Mike

lucan07
07-05-2016, 11:08 AM
Hot air gun across surface would usually deal with any bubbles.

JoeHarris
09-05-2016, 07:44 PM
Ready to pour! 18429 I made some little brackets to hold the mdf in place 18430 sealed both sides with silicone so hopefully no leaks! 18431 and heat gun and Vaseline at the ready! 18432

Wobblycogs
09-05-2016, 08:15 PM
Best of luck, looks like you've got everything prepared though so I'm sure it'll go fine.

JAZZCNC
09-05-2016, 08:53 PM
careful with the heat gun joe you can easily cause hot spots which harden at different rate. Only a quick flash is needed and only if really needed. Few air pockets won't hurt anything.

Not quite sure what the vasoline is for thou.?

lucan07
09-05-2016, 08:58 PM
Not quite sure what the vasoline is for thou.?

Vaselines for the same as heat gun apparently "Some like it Hot!"

JoeHarris
09-05-2016, 09:01 PM
careful with the heat gun joe you can easily cause hot spots which harden at different rate. Only a quick flash is needed and only if really needed. Few air pockets won't hurt anything.

Not quite sure what the vasoline is for thou.?

Cheers Dean, I will take it easy on the heat. The Vaseline was for the mdf sides to act as a release agent... I think Clive suggested it?

JoeHarris
10-05-2016, 10:25 PM
This is why you want slow cure epoxy - this a time lapse- https://vimeo.com/166112200 the movement is barely perceivable in real time. 18448 well it's done. Now we wait... 18449

routercnc
10-05-2016, 11:27 PM
Great stuff especially the time lapse video. It might be worth keeping the bridge between the 2 rails in place during initial setting up if you need a datum to DTI off to align the gantry Y rails - depending on the gantry rail design you've decided on

njhussey
10-05-2016, 11:38 PM
Looking good joe...now to wait....

JoeHarris
11-05-2016, 12:44 AM
Cheers guys - forgot my favourite photo?! 18450

JoeHarris
06-07-2016, 11:07 PM
Setting up these rails is insanely hard work!! I wish I had a straight edge the length of my rails... I managed to get one pretty much bang on but the more cap screws I add, the harder it is to keep the rail exactly straight... Time to take a break! https://vimeo.com/173678941

JoeHarris
07-07-2016, 12:04 AM
Some photos http://uploads.tapatalk-cdn.com/20160706/5ab4a877dd84b5cc56fe56f97710ca4b.jpghttp://uploads.tapatalk-cdn.com/20160706/b5e1ede6a0c545c28b2bba4614fddb39.jpghttp://uploads.tapatalk-cdn.com/20160706/7b8defa3f6299d0e02efe1c22ab4259b.jpg

JoeHarris
26-08-2016, 10:13 PM
Evening guys - I have just finished mounting my rails - whoop - and have to say that is one long and screwy task!! I have attached a video of the various sounds of the bearings moving up and down depending on what they are mounted to as the hollow shs makes them sound much more noisy than on the aluminium. At least I hope that's what it is?! I've mounted these things pretty straight, parallel and level!https://vimeo.com/180356379

Clive S
27-08-2016, 12:04 AM
Joe Stop panicking they sound fine see what they are like when you put the gantry on:onthego:

JoeHarris
27-08-2016, 12:46 AM
Thanks Clive! It's just taken such a bloody long time I don't want to be doing it again! They sound about the same with the gantry on although the next task is to get that all squared up.... I'm sure it's fine - when I give the gantry a shove it keeps going for a while before it stops which I take to be a good sign.

Neale
27-08-2016, 09:02 AM
These carriages also seem slightly rough when moving unloaded - try moving them with your body weight on them. Under load they become much smoother.

JAZZCNC
27-08-2016, 09:22 AM
Perfectly normal Joe that's the preload your hearing/feeling. When greased and under load they will sound different again and work great.

JoeHarris
27-08-2016, 09:49 AM
Perfectly normal Joe that's the preload your hearing/feeling. When greased and under load they will sound different again and work great.

Thanks Dean and Neale, reassurance is much appreciated!