resetting window motor driven arm after each round

[Da Kid]

does anyone know about a gear box with a wormdrive in it that uses a cim motor? our mentor was thinking about doing this because of the cim motors' strength.
in a related matter, what would the gear ratio need to be for a denso window motor to rotate a 10 lbs, 50 in. arm that extends to 62 in? we want it to not put too much strain so that the thermal breaker doesn't get tripped. we do have a spring on the arm so that makes it a little easier, but what would the gear ratio be without the spring, just to be safe?

[pfreivald]

Originally Posted by Da Kid

in a related matter, what would the gear ratio need to be for a denso window motor to rotate a 10 lbs, 50 in. arm that extends to 62 in? we want it to not put too much strain so that the thermal breaker doesn't get tripped. we do have a spring on the arm so that makes it a little easier, but what would the gear ratio be without the spring, just to be safe?

That should depend largely on how quickly you intend the arm to rotate.

There is a relationship between torque and power that isn't more than algebra to compute... Do the math -- an engineering mentor or physics teacher can help!

[LLogan]

Originally Posted by Da Kid

does anyone know about a gear box with a wormdrive in it that uses a cim motor? our mentor was thinking about doing this because of the cim motors' strength.
in a related matter, what would the gear ratio need to be for a denso window motor to rotate a 10 lbs, 50 in. arm that extends to 62 in? we want it to not put too much strain so that the thermal breaker doesn't get tripped. we do have a spring on the arm so that makes it a little easier, but what would the gear ratio be without the spring, just to be safe?

Just do the math. 10lb *16oz/1lb * 62in = 9920 oz*in. A window motor's stall torque is 1501 oz*in.

That means you need about a 7:1 reduction with a single window motor. That'll give you an angular velocity of about 12 rpm. You also should design it so that the window motors don't operate at their max stall torque, so you may actually need to increase the reduction some more or add another motor.

[Torbots 1197]

Originally Posted by Da Kid

does anyone know about a gear box with a wormdrive in it that uses a cim motor? our mentor was thinking about doing this because of the cim motors' strength.
in a related matter, what would the gear ratio need to be for a denso window motor to rotate a 10 lbs, 50 in. arm that extends to 62 in? we want it to not put too much strain so that the thermal breaker doesn't get tripped. we do have a spring on the arm so that makes it a little easier, but what would the gear ratio be without the spring, just to be safe?

We're powering our arm through a combo of a fisher-price and RS-775 motors. The F-P is fed into a banebots P60 gearbox with a 20:1 reduction and the 775 through a P60 with a 16:1 reduction. The output of both motors are then fed into a torque summing gear that is also tied to a custom 30:1 worm gear setup. For us, this results in around 20 RPM at the output of the worm gear under a load.

If you're to just use one CIM motor to drive this setup, I'd expect a noticeable reduction in speed as you'll probably be driving the motor somewhat close to it's stall condition. Our arm is designed to still limp along even if one motor happens to die during a match. Don't be fooled by the size of the motor; the F-P motors have the highest power ratings of all the motors available to us.

[Mike Betts]

Originally Posted by Torbots 1197

...Don't be fooled by the size of the motor; the F-P motors have the highest power ratings of all the motors available to us.

Brrraaappp! That's one down, Kitty Carlisle...

Are you saying that the posted motor specifications are incorrect?

The CIM has a peak mechanical power of 340W versus the FP at 292W. Add to this the additional gear reduction required to gear down an FP, and the CIM wins every time.

Now, if your intention is to build a smoke generator, the FP is a natural choice...

JMHO,

Mike

[Al Skierkiewicz]

I am guessing that the phrase "for it's size" was left out.