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View Full Version : Looking into converting my Mill to CNC



T0rnado69
22-03-2014, 01:03 AM
ive had a mill for a fair few years now
its a clarke CMD1225D
(http://www.machinemart.co.uk/images/library/product/large/06/060711226.jpg?2)
i need to make a stand for it to sit on with a suds tray etc.

and will proberly sort that out once ive done a welding table.

but i did see a picture of this mill converted to cnc,
and thought WOW....

what a great idea...

now i want to work out whats needed to do the conversion...

cheers all.

magicniner
22-03-2014, 10:12 AM
I plan to embark on a conversion this year and have been putting together a shopping list which so far includes;
..
1. Breakout board, stepper drivers, stepper motors and mounts.
2. Ballscrews with zero backlash stepper end bearing kits, ballnuts and mountings to allow them to replace the table's standard nuts and couplings to connect steppers to shafts
3. Milling head counterbalance system, still wavering between gas rams or a steel bar weight with steel rope & pulleys to allow the Z stepper to deal primarily with movement & positioning rather than a huge vertical load.
4. Pumped lube system, either automated or hand pumped but a simple quick plumbed in way (no pun intended) to get lube everywhere it's needed so it's not a chore to lube the mill every morning before it starts work.
..
Nice to have features include MPG wheels for each axis on the machine to allow manual machining.

ATB,
Nick

JAZZCNC
22-03-2014, 01:22 PM
Can I suggest you don't Pump a lot of money into this converting this machine as they are not very suited to CNC conversion being round column and relatively low strength.

Buying quality parts for the Electronics is recommended ie: Drive's, BOB, PSU etc as you can take these with you to another machine but I wouldn't go to great expense or trouble on the machine it's self. Ie: Zero backlash Ballscrews etc and would just do the minimum required at first with lead screws on it already.
This will give you an idea of what's involved and also show you the limitations of the machine under CNC control.

If you do go to the trouble at first it will seem great has your not used to CNC but it won't take long before you start to see it's failings and want better from the machine and start chasing it.
In time it becomes like digging a ditch your so far into it's hard to to get out and you pump more and more energy and money into it but the reality is you can't make a silk purse out of a sow's hear and your still stuck in the ditch.!!

Jonathan
22-03-2014, 03:24 PM
Did you spot mine?

http://www.mycncuk.com/forums/conversion-build-logs/6544-clarke-milling-machine-cnc-conversion-cmd1225d.html

Going for zero backlash (which is the case now - need to update the thread) does complicate matters and is arguably a bit over the top. It is nice to have though.

Regarding the strength of the mill, yes it's a round column mill so a bit limited in that respect. However if you compare it to say the X3 which is a similar size 'square' column mill, the dovetail slides and table are quite a lot bigger, plus the back of the X3 column is open so its torsional stiffness will be reduced somewhat. So overall it may not make that much difference ... but I hope it does as I've just acquired an X3! When I've put it back together I'll do some testing to compare.

T0rnado69
22-03-2014, 05:37 PM
thats a fair list magicniner.
but i dont think il do everything on this mill.
ive never had a cnc before.

T0rnado69
22-03-2014, 05:44 PM
thats good advice jazzycnc.
i understand its a manual mill and proberly not best suited to be cnc controlled.
and as you say good quality electronics can be taken off and moved to another machine.
i dont think there is much or any backlash on the mill at present, i would need to check.. but i guess fitting it with ballscrews wouldnt be cheap.

so where would be best to buy the electronics from. also i would need the software too.

irving2008
22-03-2014, 05:47 PM
The main issue with round-column mills isn't so much the strength, unless you're trying to hog out large cuts in steel, its the lack of registration on the head. To CNC the Z-axis you can only really drive the quill which limits z movement to 100mm or less. Changing tooling often means raising the head and then you lose positioning in X-Y. While there have been many approaches proposed to address this in the end none are truly satisfactory. a square column mill wins hands down in this respect.



Can I suggest you don't Pump a lot of money into this converting this machine as they are not very suited to CNC conversion being round column and relatively low strength.

Buying quality parts for the Electronics is recommended ie: Drive's, BOB, PSU etc as you can take these with you to another machine but I wouldn't go to great expense or trouble on the machine it's self. Ie: Zero backlash Ballscrews etc and would just do the minimum required at first with lead screws on it already.
This will give you an idea of what's involved and also show you the limitations of the machine under CNC control.

If you do go to the trouble at first it will seem great has your not used to CNC but it won't take long before you start to see it's failings and want better from the machine and start chasing it.
In time it becomes like digging a ditch your so far into it's hard to to get out and you pump more and more energy and money into it but the reality is you can't make a silk purse out of a sow's hear and your still stuck in the ditch.!!

magicniner
22-03-2014, 06:48 PM
Not all round Column mills are created equal ;-)
My Emco FB-2 based manual mill (the conversion I have planned) and current CNC - a Rishton based Connect are both round column but have good Z travel with excellent registration and gib strip adjustment.
I've considered doing the work to machine a slot in the column and add registration with gib strip adjustment to my floor standing mill-drill, then I remember how heavy it was when I assembled it :-O

- Nick

T0rnado69
22-03-2014, 06:53 PM
hi jonathan, i did see your thread about the mill..

i did send you a PM when i joined here,
was going to ask about the mill. but you didnt reply.

so i thought il post up a thread and get advice from fellow members.


cheers.

T0rnado69
28-03-2014, 12:18 AM
so where would it be best to buy the electronics from.
what size steppers.. nema 23 ? or .....

also i would need the software too.
and the pulleys and belts ?

thanks..

JohnHaine
30-03-2014, 12:22 PM
Zapp Automation are good for steppers and mechanical components. Drivers are a bit pricey IMHO but I'm sure excellent quality. Quick look on eBay shows you can get a BoB and 3 stepper drivers for about 75 quid. There are also a lot of suppliers of suitable psus on eBay. I fitted my Denford Novamill with new electronics for significantly less than 200 mainly from eBay.

On the question of strength of the mill, with cnc because the machine does the work you can use smaller cutters running faster which I think makes less demands on rigidity. But having a round column without a gib will makes tool changing a pain and really only a lead screw gives good z dimensional accuracy, rather than a quill feed.

Backlash is a pain, and in my experience the backlash compensation in Mach3 only works well for very small amounts of play. You may think that your screws don't have much backlash, but I think you will be surprised if you measure it. My manual VMB and Super7 both have about 0.2 mm backlash in their leadscrews - I've cnc'd the lathe with a ball screw on the x axis, but I need to convert the z axis, as it's a pain having to plan some cutting sequences to compensate for it.

JohnHaine
30-03-2014, 12:36 PM
Oh and on software, Mach 3 is pretty good overall. LinuxCNC may be better and it's free but I think unless you are comfortable with a non Windows environment you could find it harder to set up. Another point is that standard Mach3 assumes a PC with a parallel port, and these are getting rarer now. You then use the BoB to adapt the parallel port to the stepper drivers. I've followed this route on both lathe and mill but starting again I would use a USB or Ethernet motion controller. Look for Smoothstepper or CSM products, there are others around too.

m_c
30-03-2014, 09:40 PM
Backlash compensation in any software, not just Mach, is pretty much a sticky plaster approach. All it takes is for whatever cutter/drill you're using to push the table, and the free play could end up in either direction of the lead screw.
Things like always conventional milling do help to control the play, but it's still not guaranteed.

T0rnado69
30-03-2014, 10:19 PM
thanks guys for all the input.
i did look on ebay at the electronics, as you say you can get the kit for less then 200. but the sellers are either hong kong or china.
now i bought a few things before from sellers in china, but what if a stepper fails or there is a problem.... posting stuff back to china isnt going to be cheap and turn around takes longer then in the uk.

OliTech
09-09-2014, 01:24 PM
thats a fair list magicniner.
but i dont think il do everything on this mill.
ive never had a cnc before.

Hi with regard to slide lubrication I have been thinking of adding an oil pump to lubricate the slides to replace the gease nipples, and has I do a bit of work restoring motorcycles I have found a pump that was fitted to Yamaha RD125 & RD250s two strokes, the pump was designed to pump oil into the induction tract and to provide lubrication to the engine one advantage of useing this pump is that the oil discharge can be adjusted. as the pump stroke was increased as the throttle was opened.
I have not got round to fitting this yet but will let you know the results when I do.
Phil