Fisher Price used on Arm?

[Ryan Foley]

Team 60 and 254 both used fisher price motors (with big black FP gearbox) to drive their arms last year. Check out the pics, they could probably give you advice on how to use FP motors on an arm.

Here are some pictures of team 254

[kaszeta]

Originally Posted by Ryan Albright

we used fp last year in our arm to pick up the big ball. If you want to use them you need to watch the heat on them. We burnt threw a few. YOu might even think about building heatsinks for them and invest in one of the guns that takes the heat measurements. Fps can be done if they are monitored closely and checked after every match

I'd second this. Team 95 used FP's last year to drive their arm (see Pic 1 and Pic 2) , and they worked fairly well, but they do burnt out rather easily. Careful design or limiting the voltage range is a good idea. Chilling them between matches helps a lot too in a pinch.

[eddwahd]

Originally Posted by MattB703

Don't use the last set of gears on the F-P gearbox. Instead, make a shaft with a hex shaped outside to fit into the second-to-last gear from the F-P assembly. This shaft will then rotate with the second-to-last gear and it can be used as your output. You'll need more reduction after that. It the past we used a big sprocket (about 10") attached to the arm and put a small sprocket on the gearbox output.

Matt B

What a great idea!!!

I am going to dissemble my motor immediately to find the bore and sprocket i need to gear down to compensate for my last gear in the FP gearbox!

thanks MAtt, i really appreciate it. (=

[russell]

Do you guys have access to a mill? If so I envy you. You know the only time I have ever even seen a mill in person was in the portable machine shop at the portland regional last year? And I want to be a machinist too.... I think I am gonna buy that really cheap grizzly drill/mill. Thats not the point. When I said you shouldnt use the FP motor clearly I was wrong, and I should point out our team didnt use them last year (our first year) so I realy wouldnt know.

What we did do last year was use the window motor to drive a sprocket which drove the shaft our arm was on. It worked pretty well too, especialy after we put in some springs to act as counter weights without the weight. The problem was that there was no chain tensioner, so when this one genius got the idea to run a chunk of 1" square thick wall aluminum through the sprocket it cost us about a day. Anyway that worked pretty well, and we cut the power by a factor of three (in the program) and we can still pick up trash cans and chairs and such. The arm had a good ten pounds of pneumatics and such on it too. If you want strong, those motors got strong. This is the best pic I could find just now. The arm drive I am talking about is on the left side of the picture and the motor is almost cut off.

[Gdeaver]

We used the window motor last year with an additional 13:1 reduction. It can lift a tetra however we need more power this year for the arm. The van door and the window together are looking good. We used a 1/4" dryer belt. The belt will slip if the arm is pinned. This is good.

[Joe Johnson]

Originally Posted by Max Lobovsky

...You can get a hold of the FP couplers that were in the kit last year. (for some reason, there is an inordinate amount of FP toy cars in the trash. You can find one) it isn't terribly difficult to bolt a sprocket to one of those....

In my pinion, if you are going to use the standard F-P transmission, you should use the standard F-P coupler.

The best part is from the Jeep model as I recall because they have 10 spokes rather than the more typical 5.

Also, drill the shaft out from the strange dim. that the axle of the Jeep is to something normal - 1/2 inch works great in my opinion.

To attach a sprocket to the coupler, I recommend bolting (or welding) a sprocket to a thin disk that is the size of the ridge of the coupler (about 4 inches in diameter) and then bolting that disk to the coupler. It has worked great for us in the past. See the picture below.

Joe J.

[Gary Dillard]

Anyone have good/bad experience using the FP gearbox and coupler as a cantilever without supporting the end of the shaft? We've always added a support and bearing there because we were afraid that too much deformation in the plastic gears and housing would cause premature failure or demating, but I just wondered if anyone has relied on the stiffness of the coupler for adequate support. Joe I can't tell if you have a support plate there on not in your photo.

[Bruce Newendorp]

Another easy light weight way to attach to the FP ccoupler is to buy an aluminum belt pulley about 4" in diameter and machine off half of it, leaving the part of the pulley with the keyway and set screw. Drill matching holes in the pulley and the FP coupler and bolt toegther.

[russell]

Well, I dont really want to start a new thread for this as it is almost the same question. Here it is:

We are going to have an arm this year (obviously), and after reviewing the motor specs I have decided that we are going to have to use the Fisher Price motor, because of its torque. Our arm is going to be about five feet long (although it will also be able to extend to more like seven) and will need to be able to hold a sprocket on the end. The whole arm assembly should not weigh more than about ten pounds, and we will use springs as a counterweight. Basically our drive for the arm will need about 40-50 foot pounds of torque. Now I am looking at how to gear it. We will have to use two sets of sprockets, one of which (the higher speed, lower torque one) will use bicycle sprockets and a bicycle chain. Assuming that this set of sprockets gives about 1.2:1 reduction (I know it isnt much but we dont want much), and the other will give us 4.5:1 reduction the math would indicate that the arm should be turning about 20rpm assuming no load.

Now my question is how fast do you think it will actually be turning? With friction and load and all that? We will definetly use the 4.5:1 reduction set up, but what reduction should I use for the other stage if I want the arm to turn about 20rpm, or maybe a little bit less?

Thanks,
Russell
WRONG Team 1430

[Peter Matteson]

Originally Posted by Andy Baker

Look inside of the Bosch gearbox from last year (or previous years), and you will find all of the gears you need to build your very own single-stage reduction gearbox. The ring gears, planet gears, and pin-plate that holds the planet gears are all in there. Unfortuneately, the sun gear (pinion) has a larger id (5mm), as the Bosch shaft was bigger than the F-P motor shaft.

We utilized the same Bosch planetary last year by creating an adapter shaft with an interference fit and pressing it onto the FP. Although we used the whole transmission so most people at first glance thought we had 4 drill motors on our bot.

On the other hand this year we prefered a more direct mode to send the FP power into our transmission. I think many of you will enjoy the simplicity of how we use them this year...

Pete