Fisher Price Motor Into Drill Gearbox

[Chris]

John, and some other members of our team who were walking around the pit, were telling me about a team that took the fisher price motor and through some method were able to mount it directly to the drill gearbox that comes in the kit. I was wondering if anyone knew who this was and how they accomplished this task. Was it by changing out the pinion gear on the Fisher price? Somehow modifying the last stage of the planetary gear reduction? I’m wicked curious to know. Thanks a lot

Chris C.
Team 229

[David Bridge]

That would be team 177... Not only did we press new gears onto the motors to allow them to interact with the planetary gears inside the bosch transmissions, but the original design also called for a worm wheel reduction to be used to move our arm (we actually did this to both motors and ran them together to get double the power) this effectively gave the motors a 70+x reduction which we thought would have been and awesome way to hang, folding the entire robot up without having to worry about backdrive or not having enough power... however we were having trouble getting a good mate between the worm wheel and gears and and the set up was so powerful that it kept tearing the wheels apart (they were brass) so we finally wound up eliminating the worm gear and just using the fisher prices through the drill transmission as our winch

[JVN]

ah HA!
I KNEW it was 177, but my collegues told me I was mistaken.

Do you have any more info about how you guys did this?

Thanks,
John

[David Bridge]

Originally Posted by JVN

ah HA!
I KNEW it was 177, but my collegues told me I was mistaken.

Do you have any more info about how you guys did this?

Thanks,
John

Well I can tell you that after switching the gears we bored out an alluminum tube so that it had the same id as the motor and the same od as the transmission, then I made little rectangular piece out of 1/8 all. and drilled a hole in the center for the little nub on the back of the motor and to little holes which were then tapped which lined up with the holes in the back of the motor finally there were two holes drilled on either end to put threaded rod through. Next I made and all. support that slipped over the transmission with holes for the threaded rod and that was how we locked the motor into the transmission and kept it from free spinning... As far as I know the process wasnt really that complicated. The hardest part is when you are screwing the plate into the back of the motor you can only get a couple of threads in without going to far and stalling/smoking the motor (Design credit goes to Dzdconfusd... PM him if you have any more questions)

[Xufer]

hmm i wish i would have known about that at UTC or nationals heh i was talking about doing that beofre this season but my team just kept brushing it off, i hope you guys intend to go to the bash at the beach in the fall so that i can take a look at it, i would love to see it, (even in picture form) im always toying with drive train ideas especially after this year where my drive train left much to be desired, we had no torque at all. but we could get to mid field in under 3 seconds which wasnt much help when we were pushed right back to our starting position.
Just out of curiosity did you have any problem with the clutch slipping on the planetary gear box i know last year we did (driving me from drills this year) and when i stopped by 250's booth at nationals they were having problems with it staying up even when wired in place.

[David Bridge]

I believe that in the final version of the winch the clutches had been removed in favor of a dynamic electric break... I do believe that they were giving us trouble when we ran with them in our first attempts at nationals because the clutches had not been removed in that pair yet (i could be mistaken)

[JVN]

Originally Posted by David Bridge

Well I can tell you that after switching the gears...

This is what I'm most interested in.

I do not have the motors in front of me. Are the actual output shafts the same size? Did you just pop the Mod7 off the drill, and throw it on the FP, or did you use a different gear? Is there any voodoo involved?

I know there have been several threads about press fitting gears onto/off of these motor shafts, which method did you use? Anything fancy?

Thanks -- We're already learning new tricks for next year,
John

[Xufer]

yea if you guys had some pictures of those gear boxes with the modifications i would love to see them. I was lookign for a way to end that little slippage problem, becuase i am looking to use the drills for next year.

[sanddrag]

Originally Posted by JVN

This is what I'm most interested in.

I do not have the motors in front of me. Are the actual output shafts the same size? Did you just pop the Mod7 off the drill, and throw it on the FP, or did you use a different gear? Is there any voodoo involved?

John

I was recently interested in this myself. The drill pinion bore measures ~5.0mm and the FP ~.124" (from firstcadlibrary inventor files). So, you can bore out the FP gear to put on the drill but you'd have to do something really special to put the drill gear on the FP. Maybe weld it up and bore it out or press in a solid piece (tight), bore it out, then press it on the motor. I have never pressed a gear on a motor so I don't know that much about it. I do know the Tecknokats have done this a bit so you might ask Andy Baker.

[Travis Hoffman]

Originally Posted by David Bridge

That would be team 177... Not only did we press new gears onto the motors to allow them to interact with the planetary gears inside the bosch transmissions, but the original design also called for a worm wheel reduction to be used to move our arm (we actually did this to both motors and ran them together to get double the power) this effectively gave the motors a 70+x reduction which we thought would have been and awesome way to hang, folding the entire robot up without having to worry about backdrive or not having enough power... however we were having trouble getting a good mate between the worm wheel and gears and and the set up was so powerful that it kept tearing the wheels apart (they were brass) so we finally wound up eliminating the worm gear and just using the fisher prices through the drill transmission as our winch

Team 48 also used this method with great success on our lift mechanism. Two FP's mated to two drill transmissions were coupled to the second stage chain lift system on our arm. Those babies are what enabled our robot to hang so quickly and reliably all year. After the anti backdrive pins failed to keep the bot suspended in the air during the finals of the Buckeye Regional, we ultimately removed them from the drill trannies and added a servo actuated ratchet lock system to the lift to keep the robot hanging. The system was flawless after that.

I will ask the mechanical designers to explain their methods in a later post.

[Peter Matteson]

I'll try to answer as many of the questions as I can. I have a white paper prepared but have been having trouble posting it.

First of all we welded the clutches in order to permanently disable them. This is fairly easy and works well. We initially left the anti-backdrive pins in the motors but later removed them to alieviate other problems they caused in favor of dynamic breaking with the Victors. We also locked the transmission in low gear. For an output we welded 7/16" deep sockets to 1/2"-10 (going on memory for that) nuts that we threaded onto the output of the transmission. We then locked these in place with a ground down Bosch reverse thread screw into the inner part of the output.

For the motor we used a bearing seperator and a hardened pin on an arbor press to remove the pinnion gear. We had already removed the pinnion gears from the drill motors in the same way. We then created an adapter shaft out of drill rod for the problem Sandrag pointed out. We made a .002" press fit on one end for the gear to go onto and at the other end did the same for the motor's output shaft. We pressed the gear onto the adapter first then onto the motor shaft.

As mentioned we also made a sleeve to cented the FP motor in the drill transmission and tied the whole thing together with thrust plates that also worked as anti rotation. We tapped the pre-existing holes in the motor housing for 6-32 to accoplish this.

If it worked this time attached will be a tif file that contains most of the infor required to do this except for the output and drill transmission mods. Certain dims are flagged as needing to be checked because we had to tweak them to get things to work correctly.

-Pete

[Edit] I actually thought more people would be asking about the vacuum generator that actuated our shifting mechanism than this. [edit]

[Jack Jones]

We (#1447) mated both the FP and Bosch motors to DeWalt three speed trannys, which are superior to the Bosch trannys - the shift ring gears are all metal and will shift on the fly, especially if you radius the inlets.

We cut our own 32-15 pinions out of 0.3" titanium on our (USA-TARDEC) watercutters and pressed them onto the motor shafts. Used Loctite 680 retaining compound just to be sure the press fit would hold. Drive setup worked great except that our mounts didn't hold the trannys well enough; they wanted to spin, so we retrofitted a bolt through the nylon assembly. Too bad that our proto-type was only used for photo-opps, we'd have discovered the problem well in advance instead of staggering through so many matches