I got together with a Home Built CNC guy I know by the name of Richard Moller at Shade Tree CNC after I got the Shapeoko2 and then the upgrade to the X-Carve he had suggested a chain drive replace the belts since I had a long bit of issue with steps missing and such. He calculated it all up and got me pointed in the right direction to get the parts. I had to put it on hold off and on seems like a little over a year last night I actually did some testing and it looks possible. I ordered gears for the steppers and gears to keep the chain in place, I found the measurements we came to would have the chain hitting the VWheel or at least being way too close for my comfort so I will have to drill a new mounting hole in all brackets for the chain to attach to. I have some .5" thick Delrin I am going to try for the spacers. It will be threaded and use the existing holes the original pulleys were mounted to as well as the lower stepper motor bolts, if there is too much play in the motor I can always switch to longer screws with a nut on the inside. This is what I have so far, now I am also waiting on some .5" aluminum stock and longer pins the ones I got will not work like this.
Sounds interesting. One thing that came to mind pretty quick was that the chain will have to go through some very tight radius turns, so I was wondering if any error would be introduced by the fact that a chain is by nature a set of connected straight lines, so it won’t exactly conform to the shape of a small pulley like the existing belts do - you’d have little corners of extra space taken up around the pulleys.
Richard has been running his home built machine on this #25 automation chain for a long time and the chain can actually do some fairly tight radius’. I will definitely do more pictures on every step of the way here - I know the belts have been a pain for a lot but to convert as far as ball screw is no cheap task this will have me into under two hundred bucks for the upgrade and not a ton of modification to the actual machine.
I do have side shields already but removed it to reach the belt area. I also have an enclosure with a full size dust collector I am working on a pull through dust system that allows me to let go of the dust boot altogether.
OK, I didn’t see from the pics that pulleys and wheels had been switched for sprockets.
I was looking at making new pulleys but the sprockets will ease my thoughts of slipping.
Very nice and great idea !
Sure got my attention, pinion drive is just so expensive 
I’ve read that chain drives are difficult to tension and can have significant lash. It’ll be interesting to see your results.
There must be some space between the pins and shafts. Not much space, but multiply that over many links and it might be significant. That leads me to think that tension is going to need to be really high to avoid lash when the prongs engage. That’s unlike a belt, which will always push in either direction with some force regardless of tension. But, does that make a chain a poor choice? Am I even thinking about the problem correctly? I don’t know. 
What I’m trying to say is that it’s very likely that the inner diameter of the bushing in each link is not exactly equal to the outer diameter of the pin, which means that there would be some unrestricted free play that would allow the chain to expand or contract without significant resistance.
I doubt that it’s very much, perhaps 1/100th of a millimeter per pin? Just guessing out of my ■■■here. But, even if it’s really small, if you multiply that over enough links it might add up to a significant amount. But, I don’t know if this is even a problem. And it’s certainly less of a problem once the chain has enough tension.
Like anything, you’ve got to practice it every once in a while to maintain the skill. 
That’s a very good point.
I’m willing to concede this debate. I just don’t know enough about it to go any further. I’m still eager to see the actual results, though.
We are all just really guessing but some noteable things with the automation chain from a fellow cnc users unit - no need for oil or heavy tension and no massive backlash - he has been running on chain for years on a larger home built unit on the same chain set up so I have faith this will be a good alternative for me. I just got the aluminum bar stock in and an aluminum end mill specifically for the job so I will be making new gear brackets now. As well as new Y Axis Braces the ones I eye balled with a hand drill lack to my standards…
Well I got some Aluminum and a special 1/8" mill bit for Aluminum and 1st attempt when it went to bore the holes it pushed the bit up into the collect so I stopped it reset it all and tightened it slowed the depth of cut and plunge rate - forgot to tighten the stock on the second run and it almost killed it… reset tightened and ran a 3rd time it snapped before it got to the profile cut - probably weakened the bit with the loose stock run.
The pin holes are all good tho.
I switched to my 1/8" router bit from home depot - and 3" sections of delrin. It cut no problem. I reduced the depth of the holes and the depth of the profile to .25" and cleaned up the holes on the drill press and the profile on the router with a pattern bit and bearing. checked it against the print Richard made and within .01 on the thickness I can always wet sand it a bit to clean it up. the 1/4" dowel pins fit nicely and the other holes are perfect for tapping. I need to get more taps Friday cleaned the shop and now they are MIA.
That is one dusty laptop dude! 
it is just the keyboard i run a full system out here in the shop… and I am making a control center to keep the dust off of it.
Fully Assembled and installed. Something was a bit off only 2 of the screw lined up properly but it seems good enough for me to at least test it. I opted to just tear down the entire machine and redo my Y plates too - these ones were rushed and not very good.
There needed to be a new mounting hole for the new location of the chain. I just eyeballed the drill thru front and back.
adjusted the eccentric nuts 100% again since it was stripped and cleaned everything back to factory I am not sure why i did not notice it before but I only have 5 chain links so i have to order more before I can even reassemble and reprogram the steps. I think the hardest part is grinding a flat on the bolt and drilling a hole for the link to lock onto.
I only bought a 10’ section of chain and 4 links for some reason not thinking got the 2 side chains done and about 3" short on the x Axis I could probably make it work but I want to give it a full chance to work properly … I ordered a 10 pack of links and an additional 10’ section of #25 chain should be in from Amazon Tuesday or Wednesday. That gives me time to lay out and make better y axis brackets. This will be test running before the weekend!
Any chance you’d be able to post a link to the chain you have used
This is the actual Chain I am using, I bought 2 - 10’ lengths I have not measured it yet but 1000 mm + the length to go up over the stepper sprocket may need a couple inches over the 10’ length. I did not thoroughly investigate the length issue yet but it is standard automation chain #25. And do not forget if you try this it is 6 connection links. I also have to figure out a better way to do the adjustment bolts grinding a flat and drilling thru a 5mm bolt for the link to go thru is not easy I went thru about 8 of them the other day without success. 5 down 1 to go.
Since I was here and noticed the Y plates I made were really not good - I used thinner stock being cheap and drilled the stack all at once so holes were off. This round I took the time and did it right, never enough t nuts I ordered a pile from Inventables to finish the upgrades all at once. No flex anymore and the wood spacers at each point of both rails are barely touching I may set up the digital indicator to test over all flatness of the waste board now I feel it is square and level all over.
So far the only hold up I have is when I pulled the wire channel bracket off the back of the x axis I lost the screws - screws and parts all over the shop but they are MIA. So I not only ordered t nuts I ordered the correct bolts and the upgraded X Axis I wanted to go for the upgrade but that is not in the budget this month. Trying to keep the rigidity of the steel bar upgrade I did and lose some weight. I still have hopes of putting the water cooled spindle in this unit.
Skip the drilling. Make a “hook” out of a screw.