Mounting / Connecting The Fisher Price Motor

[Paul Copioli]

What we have done for several years now is make a round part that fits into the octagonal hole and feeds all the way through to the back hole. We use either steel or aluminum and screw the round part through the slots in the octagonal part. It makes for a very strong connection and allows you to put a potentiometer on the back side. A picture says 1,000 words so I will find a picture in the next hour or so. I will send another post with this picture.

This connection held up even when we broke our output shaft at Chicago two years ago (sorry 93 and 107).

-Paul

[Paul Copioli]

Here are the views I was talking about. I couldn't find any pictures, but I have the solid model views. The real parts were made directly from the model so the views are accurate.

-Paul

[Andrew Blair]

Paul, today we did something very similar, and it works beautifully. Much better than trying to use the black coupler. One thing we found, is that by using 5mm bolts, which are larger in diameter than the slot is wide, and then drilling the slot out slightly to accept the bolt, makes for an extremely strong connection, even without the bolts tightened down.

[Nitroxextreme]

Are their any lighter ways to make these FP gearboxes usable?

My team is trying to use them, but without being able to make the output shaft able to hold sprocket, they will be "useless".

[Andrew Blair]

Originally Posted by Nitroxextreme

Are their any lighter ways to make these FP gearboxes usable?

My team is trying to use them, but without being able to make the output shaft able to hold sprocket, they will be "useless".

This really is an easy (with access to a lathe), light way to do it. The entire aluminum slug with bolts weighs maybe a few ounces, and the necessary shaft support can be as light as you want to make it.

[Nitroxextreme]

Originally Posted by Andrew Blair

This really is an easy (with access to a lathe), light way to do it. The entire aluminum slug with bolts weighs maybe a few ounces, and the necessary shaft support can be as light as you want to make it.

Are you talking about making a metal "slug" to fit in the octahedral shaped plastic piece?

I'm still a bit confused how this would work? Would the slug have a shaft on it like the whole thing milled/lathed out of one aluminum rod?

[Andrew Blair]

Originally Posted by Nitroxextreme

Are you talking about making a metal "slug" to fit in the octahedral shaped plastic piece?

I'm still a bit confused how this would work? Would the slug have a shaft on it like the whole thing milled/lathed out of one aluminum rod?

Well, really whatever you want. Heres how it breaks down:

On the white output of the fisher-price, there is an octagonal hole formed by tabs. It appears to be round at first glance. So, by maching a round slug that fits in this octagonal hole closely, you have now effectively "Plugged the hole". Between the slots of the FP output, you drive bolts through, into holes tapped on the Aluminum slug. So, the slug can then have whatever you want on it. Want to drive a 1/2" shaft with it? Machine and broach a 1/2" hole into the Al slug! All it is is really plugging the output hole with something that is easy to interface.

[Nitroxextreme]

I was talking with one of our mentors about connecting to the FP gearbox output "shaft"

And the first thing that he said was that a 1in or 1 1/2 in nut would fit in there

We haven't been able to get a nut that big yet, but I believe that this may also be able to solve our problem

[Andrew Blair]

Very interesting solution. But arn't most nuts hexagons, and not octagons?

[Rick TYler]

How about a proven method to take power off from the next-to-the last gear? IIRC, this stage is about 450 RPM.

[Manoel]

Originally Posted by Rick TYler

How about a proven method to take power off from the next-to-the last gear? IIRC, this stage is about 450 RPM.

We did that last year, cutting the gearbox to eliminate the last stage. I don't remember exactly how we did it, tomorrow I'll take a good look at the robot and post the results here.