Re: resetting window motor driven arm after each round
 

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.

Re: resetting window motor driven arm after each round
 

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.

Re: resetting window motor driven arm after each round
 

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

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

Re: resetting window motor driven arm after each round
 

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

Re: resetting window motor driven arm after each round
 

Evan,

That has to be one of the coolest things I have seen. Great idea!

btw, I absolutely love your robot this year! Good luck at WPI this weekend.

Re: resetting window motor driven arm after each round
 

Okay, I'm not going to let 190 get all the "cool credit" anymore :P

Here's some pictures of our spring loaded window motor disengager. We use it to lower our arm after a match. We still have to power the robot arm to get it in exactly the place we need but we use it to save on time a little bit as well as making it easier to carry to the pits.

http://i.imgur.com/O1NR1.jpg

We have the window motor coupled to a 3/8 hex shaft, which drives everything. The "seam" in the sprocket is where our makeshift dog connects to the sprocket in order to drive it.

http://i.imgur.com/2NsiC.jpg

Here clearly shows how the dog and sprocket connect, transferring power to the shaft. There's a hex pattern in the sprocket, but it rides on a round portion of shaft so the arm can free spin when disengaged.

Re: resetting window motor driven arm after each round
 

Timing is everything....:rolleyes:

My school is blocking the pictures, do you have any other way to display them?