Seeing as the fisher price motor is illegal this year, has any team adapted their gearboxes to accept legal motors?
The Fisher-Price motor from previous years is in the family of ‘500-series’ motors. Pretty much anything using the same case size, like an AM-9015, BaneBots RS550 or RS555 will fit into the same mounting geometry as the FP motor. The only real part that’s specific to that motor or transmission is the pinion, some of which are 19T 32DP, and then there are a handful of other sizes out there.
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.
How does one go about pulling the pinion off of the FP motor to swap it onto the correct AM motor?
With a gear puller like this one:
You can also make your own using a short piece of 1x1x1/8 wall box tubing, by cutting a slot in the bottom and tapping a small #4/40 hole on the top side.
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.
As stated previously, you can take the pinion from the fisher price and but it on one of the legal motors with the same motor housing. However if you don’t have a gear puller…
My team has had a lot of success with the FP gearboxes in the past on our Rebound Rumble bot we used 4 of them actually.
We don’t have a gear puller but if you have a shop press you can still take the pinion off the motor. We have a 1.5x1.5x.125" piece of steel angle that we cut a notch in that can fit under the gear. Just set the motor and gear up on the press and put a 4-40 bolt on the shaft to press the motor off of the gear.
Some of the FP gearboxes we have actually come stock with 4 mounting holes. 2 holes fit the 500 series motors and the other 2 can fit RS 775’s. We bought some of these pinions (http://www.andymark.com/product-p/am-0604.htm) that fit the 9015 motor and 500 style motors but you can also bore out the center to fit the 775 as well.
Hope this helps!
I’ve actually got an array of 32DP Pinions from a few different RC car manufacturers floating around somewhere.
We ran (2) different sizes of Robinson racing pinions (23T, 17T) on our revised shooter in 2013, and found that they don’t like to be run with just the set screw alone to retain the pinion. After losing a pinion along the way (It might have been during testing, it’s been a while) we started to apply a drop of loctite 609 to the pinion’s bore prior to installation, and then tightening the setscrew as normal. We also swapped the set screws to cupped-end screws, IIRC, and haven’t lost a pinion after 3 Off-Seasons, a dozen or so matches at the CMP and a bunch of demo stuff.
Our revised Arm transmission ran this guy from AM: http://www.andymark.com/product-p/am-0896.htm which has a 6-32 set screw compare to the #5 set screws in a lot of RC-Car pinions. After numerous burned out motors, 5 or 6 events of abuse, I’ve never seen one of these slip, and I’d imagine that if it were going to slip, a 550 at stall would do the trick.
Also, AM actually stocks the ‘standard’ 19T pinion used in some FP Transmissions, so if you really wanted to, you could use that one with the AM-9015 and shouldn’t have any problems: http://www.andymark.com/product-p/am-0604.html If I remember correctly, that pinion has a .125" bore, and doesn’t like to seat on RS550’s without a bit of help. As I said above, an RS550 has a 3mm output shaft, which measures out to be something like .118", so there’s about .005 - .007" of play between the .125" pinion bore, and the RS550 shaft, which is enough to ruin any shot at a good press fit. In 2012, the team I was with used loctite 609 to fill the gap, but it wasn’t an ideal solution by any means.