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Unread 19-02-2012, 23:09
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Ether Ether is offline
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Re: Fisher Price Overheating Troubles

Quote:
Originally Posted by DampRobot View Post
The final ratio is about 1.8:1 (reduction).

We are using the 0673 Fisher Price motors

speed spinning freely of about 4800 rpm

The motor is drawing about 37 amps accelerating and 27 steady state.
How did you measure the amps?

What is the diameter of your shooting wheel(s)?

What is the design of your shooter:
- top and bottom powered wheel(s)?

- top and bottom wheel(s), only bottom powered?

- bottom wheel(s) (powered) and chute on top?

- something else?
The free speed and current you quoted above (4800rpm & 27amps) - was that at 100% PWM?


EDIT:

4800rpm * 1.8 = 8640 rpm motor speed

from the motor curves, an 0673 drawing 27 amps at 8640 rpm is getting only about 8 volts.

So, you are gearing your speed up and then dropping the voltage down.

I suggest that you get rid of that second-stage gear-up and run this thing with a net gear-down ratio of 4:1 instead of 1.8:1




Last edited by Ether : 19-02-2012 at 23:19.