Chain drive ? What is worth it ?

Hey,

I see several videos in Youtube, that CNC is using chain drive instead of screw or belt.

https://www.youtube.com/watch?v=x-tDJAon3Ag

Someone can share experience about it ? Most interesting is accuracy and speed, lubricating and how stepper motors like nema 34 is working with chain tensioning.

I am thinking about 3 x 3 meters cnc, with 3,5 kw spindle, nema 34 hybrid motors. It will be designed for MDF milling.

Chain drive is terrible.

Hi Morph - Chains have been around for a long time and they are used on many industrial machines. Used correctly they will build a good machine but if you are to use them for MDF the dust will get into them and eventually create problems. Next step is belts and they will build a good machine for MDF. You will need a 25 or 30mm wide belt don't expect a 6 or 8mm belt to do the job..... No maintenance needed except the occasional retensioning. Once the belt settles down I find that it stays tight and accurate. Next step for 3m is rack and pinion and the bees knees is linear drive. Each step is more $$$ but better quality, less maintenance etc. You get what you pay for. So all of this depends on your budget and your expectations and the reality of what you want to do. eg if you expect to build a machine that can cut to 0.01mm accuracy then do a lot of reading and thinking to tone that down a bit. If you need +/-0.1mm for MDF then that's very doable with chains, belts, R&P. Each has its pros and cons. Also put a lot of thought into the dust extraction, your going to need a really good one!! The forum has all the answers, its all here and been done before just keep asking or searching... Regards Peter

afterthought - why interest in hybrid motors plus chain drive? and NEMA 34's? Nema23 or 24 will do your job easily and save heaps of shekels seems to be putting the $$$ into the wrong bits. You need to design a machine in CAD then fully cost it then look at the cost/benefit of each bit. Then you will understand your situation a lot better....

chains are not exactly precision compontents they will work and probably work over long travels but the backlash and inaccuracy you are going to get will be huge also sprockets wear overtime slowly increasing backlash and travel accuracy. If you don't need any level of precision, surface finish, rigidity or longevity they will work but a decent belt system wont cost that much more so I would recommend spending a little bit more money on belts.

Hey all, late reply...

I read all comments want try do small test with my old build... But noething good happens, because I dont want drill my frame, plus after some exploring in internet, I realized, that its not worth do it... I found pretty good solution about how to protect chain drive from dust, and it looks like normal. Brother CNC do the same with ATC gearbox, to ensure, that coolant will not get inside - just pressurize gearbox. I believe, that it will work with dust too.

I still have one idea for that, try make 6 meters x 1 meter CNC, middle heavy moving head, some chain drive and Chinese BT30 spindle with regular 7,5 kw induction motor, to try machine wood log. As I understand now, with 2-3 pairs chain (for reference - google for MB OM642 engine chain), and with some special design, I can get 0,2 mm accuracy over 6 meters. For summer house building it should be nice, but need aditional testing, and info about house logs... But sealed box with some oil, and air pressure applied to stop dust get into that box required. But its still in plans...

Seems that best way for me now (for MDF, plywood machining) will be rack with some belt gearbox and hybrid Nema 34 motors, because table size will be about 2500x1500. But as You said, peteeng, do everything from mind is pretty hard and not systemized. First need spend some time with Fusion 360... It will be much easier to buy aliuminium profiles and get custom parts for head connections...

Hi Morph - Look up your local industrial machinery or engineering supplier. They will have a range of roller chains to select from. The engine chain you refer to won't be available in the lengths you need? Plus industrial roller chain has a range of accessories, joiners tensioners pulleys idlers etc They will have a very good catalogue of parts to choose from. Peter