We’re looking for good ways to engage the goofy output shaft for the FP gearbox that will handle the torque it can deliver. This has been done 1000’s of times so there are surely some good methods out there. Let’s see 'em.
One year we machined a plug out of hex (I think it’s hex?) stock. Last year we bought some couplers as sold by FP, and when we got them weren’t very happy with their performance – but that’s okay, as we ended up removing the third stage anyway to get more speed out of the thing.
In previous years, we’ve taken a piece of PVC with the correct outside Diameter to fit inside of the octagon on the FP Transmission and then shot a bolt through both the Transmission Output and PVC. It worked well enough for our conveyor systems, but I’d be a bit worried about using the PVC method on anything more than that.
I know some teams have used modified the cases to accept a 3/8’s Hex Shaft on the second stage. This seems to work pretty well too.
We made a plug out of hardwood, and connected a sprocket directly to the hardwood. An axle going through both the sprocket, the wood, and if I recall correctly the gearbox as well, supported the otherwise cantilevered load.
another method i’ve seen, probably best suited for low torque applications, is inserting a pipe into the hex hole and clamping down with a hose clamp. don’t have experience with that one.
I included several methods in the back of this paper.