paper: Belt Driven VersaChassis WCD - Step by Step guide

[asid61]

Originally Posted by lamk

The versablock is designed so that one can slides it up and down the frame tubing. One can position it to the desire C-C distance with or without CNC capability.
If one have the CNC capability one can mill a slot and use the vex bearing block (P/N 217-3436) for a more compact solution:


The question that begs for an answer is the necessity for a chain tensioner.
This year's kit chassis AM14U is belt driven and has no belt tensioner.
From what I read timing belt usually does not stretch and theoretically if you have the optimum C-C then you just set it and you're done. But what is the optimum C-C distance? Is it the distance that the WCP calculator spits out using the pulley size and belt size?? I felt that there is more to that. When I build the prototype the belt tension has a significant influence on binding and the ability to rapidly go backward and forward without slop. Too tight and things bind, too loose and there is slop.
Right now we are using the Cam belt tensioner to adjust the tension until we have a smooth drive train that is also responsive to rapid change in direction.
My guess is once I find the right tension than I can leave it alone but what is the best way to find the optimum C-C distance for the optimum belt tension without using a CAM tensioner. Does anybody have a good formula for the optimum C-C distance?

Ken Lam

From what I've read, you should put in tensioners regardless because of the tolerances required for belt engagement. Adding a cam tensioner is less than 0.1lbs anyway, so there's no reason not to have one.