Re: Do you have to use 2x1x1/8" tubing for a WCD?
 

We have used 9mm HDT. That ratchets when we go from full forward to full reverse. This could have been the width, profile, or pulley size as well changed all three for this year.

This year we used 15mm GT2. That is also what 2415 uses. We plan on using this in the future. We didn't experience any ratcheting.

I have heard multiple teams shredding XL belts.

Re: Do you have to use 2x1x1/8" tubing for a WCD?
 

There are always UHMW clamp tensioners, but screw/CAM tensioning is so much cleaner and more effective, albeit being slightly (but not significantly) more complicated.

Re: Do you have to use 2x1x1/8" tubing for a WCD?
 

A 1 1/8 TCT hole cutter, available under the Ideal brand from Lowes, can be used to make bearing holes for FR8 bearings if proper machining equipment does not exist. Best thing short of a CNC, boring bar/head, or reamer.

Re: Do you have to use 2x1x1/8" tubing for a WCD?
 

We've used a "poor-team's" version of WCD for several years now. I hope I can make this make sense without pictures...

We put oversized holes in the 1x2x0.125 chassis rails to allow for the live shaft to be adjusted both horizontally and vertically. The bearings are actually supported on 0.25" plates that are "boxed" around the rail. These bearing plates are actually on the outside of the frame, held square by a plate across the top and bottom. The overall result is that we are able to adjust our outside wheels horizontally for chain tension and vertically to control the amount of center drop we need. Once the center drop amount is fixed, we simply place a shim between the bearing block cross plate and the chassis rail.

I suppose this system could be adapted to any chassis rail structure, as long as it was stiff enough.

- Mr. Van
Coach, Robodox