pic: Sliding Wheel Chain Tensioners

[Ice Berg]

Marketing these was certainly not my initial intention in designing them, which is why they are made from aluminum tube and why they do not require much machining. My team also doesn't have the capability of producing any large number of these. However, if they do work, I imagine they could be quite useful. I plan to make a few variations of these in the next week or so to test them out. If they do prove to be successful, AndyMark would be the company to market them if they were interested.

[MrForbes]

When you try out this idea, I suggest you look up the torque specification for the size of bolt you plan to use. Get a torque wrench, and see what happens to the tube and channel when you tighten the bolt to spec torque with a spacer, then remove the spacer and try again and see what happens. I'd be interested in the results.

[Ivan Helmrich]

We did something similar but used a short section of 1" 80-20 instead of tube. No need to slot the frame, the slot in the 80-20 worked fine. We just drilled a 3/8" hole through the 80-20 to hold the axle. We used 2 bolts from the bottom up into the slots. I think this is about the same thing you proposed in your second post. It worked really well but I'll be interested to see if it will hold up when the floor isn't so slippery. The loads on the wheels were pretty low this year. I guess a scheme with a bolt threaded into the end of the 80-20 would make it stronger as would using more bolts from the top or side.

One thing that was a problem was that a couple of our corner blocks were a little thin. The channel got a bit squished and the wheel mounts were too tight. We solved this on the belt sander but it was kind of crude. Next time we'll shim around the corners if needed.

You have a good design there, lighter than the 80-20. I'm curious if your axle holes got oblong. I was a little worried about ours but it seemed to hold up fine for the one regional we went to.

[kapolavery]

Yea the chasis will flex when you tighten the bolt.. thats what happend to our robot this year. To fix it all we did was just cut aluminum blocks, drill a hole for the bolt to fit in, slide it into the channel of the chasis, and then tighten.

Neat Idea.

Andy Mark Sells something that tightens chains though.

http://www.andymark.biz/am-0286.html