Our team outsourced the cutting of bearing holes for our tank-style drivetrain. We use 1"x2" aluminum tubing. The holes were cut but around 1/8 too wide, so the bearings are now very sloppy. The CAD had the hole’s diameter set to 1.125". The facility’s processing time is too long for us to get it complete by our first event. I would greatly appreciate any suggestions or possible solutions.
I have considered making small aluminum sheet plates, with 1-1/8" holes to go over the existing holes, and riveting them into place.
You could have little gussets with the correct bearing bore and then rivet them in, that is one option. Another option could be to use 1.125ID tube with the oversized OD and cut spacers from the tube to slip over the bearings and then insert the assembly into your drive tubes.
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This vexpro part (217-4183) seems like exactly what you’re looking for. You wouldn’t have to manufacture the plates:
It also has an alignment notch so you can easily cut them in half to use with one bearing. https://www.vexrobotics.com/versaframegussetsandmounts.html
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Versa blocks
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I have welded a bead around the ID of holes that were over-bored and then re-machined them to the right size.
All of the above options are less effort/better though.
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Thank you! Now I know that the plates can be used. TIs there a way to align it well enough to keep the wheels parallel to each other?
I do think the plates are more feasible, although welding and machining would probably best for alignment.
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The versa blocks just bolt to each other and slide where ever you need them to be and get tensioned with the cam.
Its what we’ve used for the last 2ish years
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+1 for versablocks. Especially for a drivetrain they are certainly your best bet.
AndyMark sells a similar product with one bearing hole:
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Thirding Versablocks, although if they’re out of budget the bearing bore plates will work as well. I think the best way to ensure that the plates are aligned axially is to assemble as much of the drivetrain around them as you can (axles, bearings, chain / belts, and gearboxes) and then match drill the rivet holes through the plate into the tubing. Lots of clamps and extra hands will make this process easier.
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Nearly identical to the Andymark part but half the price (because it’s a 2-pack).
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Thanks so much for the help!
I will go for our own plates first. They seem simple enough to make with my team’s drill press, and there is no shipping and processing time involved (had we had more time, I would probably get the Andymarkhttps://www.chiefdelphi.com/t/bearing-holes-too-big/378586/10?u=thomasart or Vexpro plates (Bearing Holes Too Big))
The versablocks do seem like the best option though. Thanks everyone!
P.S. I just recalled we have the siderails from the KOP chassis. We might as well just cut them to size because the bearing holes are already drilled out.
Indeed.
Mostly wanted to give an extra option if you happened to have a welder handy and didn’t want to wait for shipping on anything.
Yeah, its quiet a neat trick. That will definitely be something to try out, in the off-season. We have a rather limited resource of bearings at the moment 
Fourth+ for VersaBlocks, if you have the space. The two sides will automatically align to each other. The plates will work but you will have to spend time to align each pair
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If you use the bearing block remember to order the cam
Roy
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This might be a long shot, but is the bearing hole actually 1.25" ? If it’s exact then you just need to find a 1.25 OD hex bearing. Much less work and far less redesigning.
Yes, they would probably work best here. I think I will give the plates a try first though.
VersaBlocks+5 are great if you dont have the means to machine those bearing holes!!