AndyMark is out of the 4:1 AM0002 gearboxes again until next Tuesday. I was waiting till today to order some but they were snapped up between the time I got the email last night that they were in and this morning when I found out they were available. Now we are more than behind. What are the options for a gearbox for the Fisher Price Motor? It seems weird that nobody makes a simple gearbox like those for the CIM motors for the FP motor or the Banebot motor. I’m looking for probably 10:1 total reduction. Are there plans for gearboxes somewhere? Also we had no luck last year getting any Dewalt drill gearboxes. It seems that the local DeWalt service center went out of business and the regional one will not give out defective drills due to, their words, “liability reasons”. Our machining capability is pretty much nonexistent but we can call on a shop to turn out some parts if needed and not terribly complex.
You have several Fisher Price gearboxes. They all have gears with various reductions. We are using some of them with a 550 to get the necessary reduction we are looking for. With careful measuring and maybe a couple trial and errors you could probably use a drill press to make a gearbox out of some of them. I think the first stage is something like 7 to 1 but count the teeth and find out. Hope that helps.
Bruce
We’ve opened one of the Fisher Price boxes and the gearing is different at every stage as is the gear mounting. I was hoping someone had a plate design with the holes located and a parts list.
Which brings me to another question. What size are the mounting holes in the FP motor? I need to order mounting screws.
But then you don’t get the engineering experience!
Actually, take a look at http://www.chiefdelphi.com/forums/showthread.php?t=72536&highlight=gearbox and see what reverse engineering you can do to steal the concept. Make sure you scroll down far enough to see the current version.
We made one using the first stage gear from an older FP gearbox, which has the 3/8" hex hole in the gear. The high precision plate that locates the motor relative to the gear was made using a cheap vernier caliper from the physics class to measure the sizes of the gears and the spacing, and lay it out, and a small drill press and Forstner bit to drill the 7/8" holes. You can’t see the hex part of the shaft, but it’s there, between the bearings. The hex shaft has to be turned to fit into the bearings, alternately if you could find some bearings with 3/8" hex holes in them?
http://www.andymark.com/product-p/am-0439.htm
I’m no expert on this subject, but let me throw a couple thoughts out there and I know the CD community will help refine them for us.
It appears that the pinion and 1st stage gear in the FP trans are 32DP. I base this on this pinion at AndyMark.
From what I remember, and here is where I may need some help, most of the stages of the FP trans use the same DP gears. So using the equation for determining the center to center distance for gears, CtoC= (N1+N2)/DP, where N= number of teeth on the gear, you should be able to build your own transmission quite easily.
For each gear interface, adding .003" is a good idea to account for manufacturing tolerances.
or add 0.010" and machine it to within 0.020" like we did 
The one you made looks very nice. I can’t see the shims in the picture.
We are making something similar with two FP motors. Our plan is to cut the motor pilot holes using a centering endmill from McMaster (8918A148). I posted the gear picture earlier.
Oh, and we are using AM-0439 bearings, so our shaft only needs a little machining, on the other end of the load mechanism, where the encoder will mount …
While looking around for supplies in the past I did find a supplier for dewalt gearboxes, looks like they still sell them.
http://www.robotcombat.com/products/dewalt_gearboxes.html