Fisher Price Motor Replacement Gearbox

[jgannon]

Originally Posted by Joe Johnson

Note: it takes about 15 minutes from start to finish to take a FP motor and get it running in either the 42mm or the 36mm gearbox from Banebots.

Dr. Joe, could you briefly go over what the 15 minutes entails work-wise and tool-wise? We like to fly by the seat of our pants with respect to tools ("Chain breaker? What's that?" was a phrase I was not thrilled to hear three weeks into build last year), so if we end up ordering one of these gearboxes after kickoff, I want to make sure we have what we need to make it work.

[Joe Johnson]

Originally Posted by jgannon

Dr. Joe, could you briefly go over what the 15 minutes entails work-wise and tool-wise? We like to fly by the seat of our pants with respect to tools ("Chain breaker? What's that?" was a phrase I was not thrilled to hear three weeks into build last year), so if we end up ordering one of these gearboxes after kickoff, I want to make sure we have what we need to make it work.

This is a rough sketch of the process:

• Remove motor from FP gearbox
• Remove pinion from motor (use gear puller if you have one or press it off with an arbor and a yoke under the gear or grind it off - gently gently -- don't damage the shaft or the motor innards)
• Remove motor from Banebots Motor/Gearbox
• Cut shaft of FP gearbox to same length as Motor from Banebots (Dremel with a cutoff wheel works fine)
• Either open up hole in replacement pinion OR remove spline on FP motor shaft -- pinion will split if you use the standard hole and the splined shaft!!!
• Press pinion on to FP motor (use an arbor if you can or a vice if you are careful) -- try to keep things as square as you can to avoid damaging the motor
• Assemble FP motor to Banebots Gearbox
• DONE!

That is it*.

I am hoping that I can get Banebots to put something up on Instructables or on their website or perhaps even a whitepaper here on ChiefDelphi.com Stay tuned...


Joe J.

*If you are concerned about the motor "breathing" then you can space the motor back from the mounting plate (I suppose that washers will work just fine, but you may want to make a fancier one based on your level of paranoia and/or your access to machine tools). If you do, you will need to replace the motor mounting screws in the Banebots gearbox with longer ones. They are M3 or M4's, it is on the print -- don't make the screws too long or you will screw up the motor -- it is not too fussy but you have to be aware of the issue and make sure your motor spins fine after you tighten down the screws). Also, you will have to make the motor shaft longer by the thickness of the spacer so that the pinion ends up in the same spot as it would have been in had you not spaced the motor back. Not too tricky but something to watch out for. Note: it is a lot easier to shorten a shaft than to lengthen it -- be careful!

[sanddrag]

When we did the dewalt gear on the FP motor, we found that using a good quality vise (mill vise) to press it on was far easier than using an arbor press.