adapting the fisherprice gearbox

[s_forbes]

Originally Posted by thefro526

If you decide to use an AM-9015 which is physically identical (within reason) to an FP motor, you should be able to swap the pinion from the FP onto the 9015 without issue. If you use an RS550 which has a slightly smaller shaft diameter (3mm vs. .125") and lacks the knurling that the FP and AM9015 output shafts have, then you may need to look into a pinion with a set screw, or some type of retaining compound like loctite 609 to get a proper fit.

We've used some pinions from the RC car market to fit these types of motors for 32p applications. We have yet to use one in a high torque application though... mostly just for high rpm shooting type mechanisms.

Something like this might fit the description you posted above.

They come in an array of tooth counts and bore sizes, and are pretty inexpensive compared to other mechanical off the shelf parts. Maybe someone with more experience from the RC background can chime in.