Adjustable Limit Switch Cam Arm for Hex Shaft

thingiverse

FRC Team 4026 required an arm on a 1/2" hex shaft to activate a limit switch (catapult design and we must stop when cocked then load the ball) so I replaced the ugly lexan hacked thing we used with this. Two parts - there's the hub, which is designed to fit snugly on the hex shaft and won't rotate, and the cam arm, which has a round shaft hole and slots allowing for 90 degrees of adjustment off of the hex shaft alignment. The two are attached with a pair of M3 bolts and captive nuts on the hub. Make the cam diameter equal to the distance between your shaft and your limit switch, and the bottom (there is a distinct "bottom" because that's the orientation we needed) of the cam should end up square to the switch when it hits. The hub will be slightly smaller than the cam. There are a few areas for fudge factors - I printed in ABS because that was on hand, but it needs a little extra room for hole sizes. PLA probably doesn't. These include a 5% increase in nut size over "actual", .5mm for the shaft size. Play with them as needed. The cam has a scale on the edge to mark alignment and the hub a small bump to align to. I added that after we made ours, so I can promise nothing other than they exist. Warning - this was a really clean piece of openscad code to begin with and got a little messy as I added cute (though probably not necessary) features, like a scale around the edges of the cam, etc. I'll clean it up when there's time, but wanted to put it out there in case any other FRC teams could make use of it.