Re: pic: 1156 Off season Fisher-Price gearbox
 

Over the years we've made a few of our own FP gearboxes, for use in applications where the motor is not likely to stall. That means, powering a roller, not an arm. They have worked well, and we didn't make them nearly this fancy. The cooling holes are a good idea. The motor location needs to be set by the mounting hole for the motor pilot (the large area around the bearing, on the end plate, just behind the gear), and not by the mounting screws. The screws are just too small to be able to hold things in place on their own.

Good work, and it's a really neat project!

Re: pic: 1156 Off season Fisher-Price gearbox
 

The gear distance is adjustable so we can use different gear ratios with this gearbox. Yes, that's true, it would be less reliable in high-load applications, but we designed this gearbox for high speed applications, like shooting and collecting game pieces, so that is probably not going to be a problem.