pic: 6 speed?? Great in theory - lets see how it works!

[Tristan Lall]

Originally Posted by Sean Schuff

Tristan - thanks for the insight into the Lewis formula. I'll have to keep that in mind when selecting components that can withstand the abuse of FIRST robotics! $50 each - YIKES! I better find a more financially responsible solution!

Depending on what sort of gear strength you actually need, you can use cheap (and relatively soft) gears in the high-speed stages (where they are less stressed) and only go with high-strength gears for the lower reductions. Also, though I've never tried it myself, getting carbon steel spur gear stock and having it hardened is probably an excellent way to control cost here. SDP/SI (and others) typically sell several inches of the stuff for the same price as a single gear. All you need to do is machine the bore, cut off a reasonable length, and add a keyway (or dowels, or whatever is necessary). Then find somewhere to get it hardened, or maybe do it yourself (and hope it doesn't distort--you'd have to inquire about the specific hardening process to find out if that's an issue).

By the way, for a 6- or even a 4-speed version to work well (it seems to me, anyway) that you'd need to be able to shift on the fly, even while pushing something, or crashing at high speed into something. (Because the chances will be higher that you'll be in the wrong gear for something, as you're doing it.) I think you've addressed that, but just in case it wasn't a priority--please make it one! Part of that involves using sufficiently robust gears, since a partially engaged gear does not evenly apply its load to the entire face width!