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eurikain
14-07-2015, 12:35 PM
Hi,

I've seen belt drive, ballscrew, rack and pinion, but what about chain ? Guys at build-your-cnc use chain drive.

For a large steel CNC, would chain drive be a possible option, at least on X and Y, considering using a large chain (like those found on dirtbikes.

Would belt drive be an alternative ? If yes, which type of belt would you use for a 2x1.5x0.3m work area ?

And if all else fails, what is the cheapest drive system you could use on such a work area ?

Thanks a lot for your help !

Procato
14-07-2015, 02:27 PM
https://www.youtube.com/watch?v=d13SGoGt0tU

eurikain
14-07-2015, 09:08 PM
Looks nice ! But the sliding system seems a bit odd isn't it ? Why doesn't anyone use chain drive out there ? So rare to see it. Popular belief is that it flexes a lot and doesn't have enough torque, but dirt bikes use extremely resistant high torque chains, dans when under enough tension, little resonance will be seen, and no flex as it is made of steel.

m_c
14-07-2015, 10:22 PM
It's just not as good a choice considering the other options.
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Biggest issue I can think of now, are if you adjust chain tight enough to eliminate backlash, then you'll get binding, so you always need to run with a bit play otherwise you'll get accelerated wear. It also needs lubricated, which generally leads to dust/dirt sticking to it (I know there are dry lubes available, but you nearly always get left with some form of sticky residue). And they need regular adjustment.
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Ultimately, belts are usually easier to implement, and longer lasting with less maintenance needed, for similar money.

eurikain
15-07-2015, 09:21 AM
So belt would be a better choice then, price wise equivalent ? Would AT/HTD belt a good choice ? GT would be a no go for this kind of work area (2x1.5 xy) ? 25mm or 30mm width belt ?

michaelw
15-07-2015, 11:32 AM
Much depends on the speed , rigidity and accuracy that you want to achieve and on design of the motor/controller/feedback system .

A rough and ready machine can use a variety of basic motion drives but as requirements get more demanding then higher quality drives are needed .

Also a machine running closed loop with independent position feedback is usually a little more tolerant of basic motion drives than a machine running open loop and which is dependent on the intrinsic accuracy of the screw/chain/belt .

Incidentally a cheap motion drive for undemanding applications and smaller machines which is often overlooked is the friction screw - just lengths of coarse pitch studding and simple nuts with backlash adjustment .

eurikain
15-07-2015, 01:42 PM
Interesting :) I have Nema23s 3.1NM, with 24V-36VDC 0.9A~3.0A Stepper Motor Driver (model CW230). I don't know much about which kind of power is needed for a belt drive, but most designs I have seen use this setup (except maybe for the steppers). I suppose that correctly chosen gear reduction will do the job :)

njhussey
15-07-2015, 02:37 PM
Interesting :) I have Nema23s 3.1NM, with 24V-36VDC 0.9A~3.0A Stepper Motor Driver (model CW230). I don't know much about which kind of power is needed for a belt drive, but most designs I have seen use this setup (except maybe for the steppers). I suppose that correctly chosen gear reduction will do the job :)
If you're looking at making a "large steel" CNC machine then you'll struggle to get any performance from 24-36V drivers....you'll need 70V to get any sort of performance. What do you class as a large steelmachine?

Edit: for a 2 x 1.5 machine you'll need higher voltage drivers and PSU.