View Full Version : Running chains on zipties
We have a little problem with our robot: since we have a gap in the frame, we added a support beneath the robot, connected to buth inner and outer c-channels on both sides (we have a kitbot drive). Up to this point everything is pretty with unicorns and sunshines.
The problem is it's now passing between two wheels connected by a chain. The chain is a bit loose and brushes against the support. We don't have enough room for an AM tensioner (http://www.andymark.com/product-p/am-0286.htm), and we couldn't find anything small enough to fit yet strong enough not to break.
I thought of wrapping a bunch of zipties on the support, parallel to the chain's movement direction and have it run on them.
Questions are two:
Will it work? (Sub questions: how well? Will the zipties give? Will it preserve more energy than letting it run on the support? What would harm the chain more? etc.)
Got any better ideas? We would very much appreciate some.
The chains are #35 series and the support is an aluminium square profile.
BTW, feel free to discuss a theoretical, unrelated secnario of chains running on zipties :P
Delrin or UHMW. Get a small, flat piece, maybe a little bit too thick for the chain. Bolt it to the support and run the chain over it. The chain will probably wear into the Delrin or UHMW a bit; this is OK, it's just tensioning itself.
While not ideal I have seen teams use HDPE as well, usually sourced from an old cutting board.
BrendanB
30-09-2012, 16:55
Delrin would be ideal but if you don't have any, grab some small diameter PVC and split it down the middle and attach.
DampRobot
30-09-2012, 19:09
I saw I team use this at 2011 SVR. I forget what team in particular, but when I asked them about it, they said it ran great and never failed on them. As far as I can remember, it was 35 chain. I've heard of other teams using it without problems as well.
Try it, and it it works, great. If it doesn't, try some of the other suggestions in this thread. There's nothing wrong with experimentation.
I saw I team use this at 2011 SVR. I forget what team in particular, but when I asked them about it, they said it ran great and never failed on them. As far as I can remember, it was 35 chain. I've heard of other teams using it without problems as well.
Try it, and it it works, great. If it doesn't, try some of the other suggestions in this thread. There's nothing wrong with experimentation.
What's "it"?
BrendanB
30-09-2012, 19:13
If you can get a picture of this area, it would be extremely helpful in offering advice!
If you can get a picture of this area, it would be extremely helpful in offering advice!
I would, but by the time I get to the robot there will be no point asking. You see, our next (and last with this bot) competition will be Wednesday, and we won't get to work on our robot until Tuesday.
DampRobot
30-09-2012, 19:16
What's "it"?
Tensioning the chains with zip-ties.
Tensioning the chains with zip-ties.
Oh... Great, thanks.
rcmolloy
30-09-2012, 19:21
In which direction does it hit the support? Top or bottom of the chain? Like many other individuals have suggested, delrin would be the best bet for this application.
After doing a bit more further reading, it sounds like it is hitting the bottom. Encompassing the delrin solution, I would personally get a nice uniform 3/8" block of any nominal length and tap for 1/4-20s while fastening from the top of the frame. Also, round the edges on any belt/disc sander to give a nice profile so that way the chain isn't hitting a 90* edge.
If you guys could provide a picture as well, this would help eliminate the problem completely!
PhantomPhyxer
30-09-2012, 19:38
I would also recommend Delrin. It is sold by Mc Master Carr in several shapes. We are currently using Derin on our 2012 Robot for Chain Guides. Just make sure you have plently of rap on your sprockets.
We usually take those AM tensioners and drill a hole through the nylon pieces and just bolt one half (as in one nylon piece) to the frame somewhere along the length of the chain. I wasn't able to find a better picture of it but you can see the top of the piece in between the 2 middle wheels.
https://lh3.googleusercontent.com/-RQpdyP7Et-U/UGjZaAUqygI/AAAAAAAAAEQ/ObT3KaB2pC0/w396-h297-n-k/0309012117.jpg
About the zipties, we have actually used them as tensioners before in very desperate situations (like at a demo when we forgot everything else) and they work for a very very short time before the chain cuts through them. We have however had chain run against metal (1/4" bolts) before and it usually is fine.
MrForbes
30-09-2012, 20:08
We used some pieces of ABS sewer pipe to tension the chains on our 2011 robot, easy and it worked well (until the axles bent but that's a story on another thread). Kind of like the PVC pipe suggestion.
Good luck!
zip ties will find a way to pop off the master link.
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