Some more VersaChassis Questions

[DampRobot]

Originally Posted by Oblarg

Really? That's somewhat surprising - in the past when I've used 80/20 to mount wheels, no matter how much I tightened the bolts the wheels eventually walked enough to loosen the belts. Admittedly, that was with plastic IGUS bearing blocks pressing against a t-slot, and not with aluminum plates clamping around a piece of 2x1, but I'd have expected the physics to be similar for similar-strength bolts with similar amounts of tension on them.

That said, there are holes in the VersaBlocks for mounting directly through the 2x1, right? So in practice you could simply slide the block until your belts are tight and then match-drill through the framing member and bolt it in place for all time. Won't work as well with chain, which expands, but with belt it should be a very good solution.

I'll give a counterpoint to Andrew here and say that you're correct, at least in my experience. If you tension your bearing blocks with a clamp, say, and then try to tighten them down, even really really tight, they will slide eventually. Maybe not in the first two matches, but I'd bet they'd slide in the first twenty. We ran a setup very similar to the VersaChassis last year, one in the regular season without cams, and one in the season with. The one for the regular season we had to check almost every match and retention frequently (we were running chain and 4" wheels) as it slipped fairly regularly, even when tightened super hard and locktited down . In the offseason, we ran 6" wheels with slightly larger sprockets and cams, and the bearing blocks never slipped. Never.

After the first installation cams aren't really there to provide an easy tensioning method. They're there to keep the bearing block from moving back. Basically, (and I've seen this on many of our robots) if you don't have a cam, the screws holding the wheel truck will vibrate loose, and the block will slip. When these things are in a drivetrain without cams, they will slip sooner or later.

So, please, just buy four cams. They aren't that expensive, and they will save you from a lot of sweat, blood, tears, and losses in the season. I know for a fact that they could have prevented one of our lost matches.