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Unread 12-02-2011, 12:38
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Exclamation CIM Motors with gearboxes: torque

Our team was using pneumatics for the arm, but then found out yesterday night that our pneumatics setup is illegal. So we want to use a CIM motor, with an andymark toughbox from previous years. Does the Toughbox increase the torque, or increase the speed of the CIM motor?
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Unread 12-02-2011, 13:02
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Re: CIM Motors with gearboxes: torque

Edit: How much torque do the CIM mtors put out? How much torque do the Toughboxes attached to the CIM motors put out?
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Unread 12-02-2011, 13:45
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Re: CIM Motors with gearboxes: torque

A cim has a Stall Torque of 2.42 N-m, or 343.4 oz-in, according to:
http://www.andymark.com/ProductDetai...ctCode=AM-0255

A toughbox has a gear reduction of 12.75:1 , which means that the speed is reduced by a factor of 12.75 and torque is increased by the same factor.

total torque of a toughbox with 1 cim: 30.855, and twice that with two cims.

please note that the above is the stall torque, and it is not recommended to work close to it.
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Unread 12-02-2011, 19:34
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Re: CIM Motors with gearboxes: torque

I'm curious, what made your pneumatics setup illegal? Maybe you don't have to give up pneumatics altogether and switch to a motor for what you're talking about.
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Unread 12-02-2011, 21:19
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Re: CIM Motors with gearboxes: torque

I would suggest that you sould consider using a much larger gear reduction on the motor. A CIM with only a gear ratio of 12.75:1 will not have enough torque to lift an arm that weights more than 4 pounds (according to the JVN mechanical design calculator). Worse than that, even if you do make your arm that light, then the motor will be going so rapidly that your arm will spin nearly as rapidly as the wheels on your robot. This will make it so that your arm will be totally uncontrolable and possibly damage your robot. If you use a 12:96 sprocket reduction out of the toughbox, then you should be able to lift the arm, but it would still move very rapidly. (you can get a 96 tooth sprocket at VEXpro)
If you are certain that you want to use the CIMs, then the GEM planetary from AndyMark would probably be the best idea. Otherwise, you could use a different motor with a larger reduction gearbox that you already have or you could try to make your pneumatics legal.
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Unread 12-02-2011, 22:36
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Re: CIM Motors with gearboxes: torque

We were trying to stop the cylinder mid-stroke with a secondary solenoid connected to the exhaust ports of the primary solenoids. That would stop air from exhausting from the cylinder, thus effectively stopping it. The GDC ruled this as illegal, per rule <R74>, yesterday.
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Unread 12-02-2011, 23:03
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Re: CIM Motors with gearboxes: torque

I think there are (legal) valves available that will allow positioning. Perhaps you can research that option, or someone else can chime in.

Since there are only a few set heights, will your design allow you to use multiple cylinders stacked to achieve the set heights?

Do you have additional Toughbox parts? You could stack 2 toughboxes, or make new plates and add additional gear reduction internally. Or use a small sprocket on the output to drive a larger sprocket. You will need to balance the arm or do something to prevent backdriving.

You could also use the output of the toughbox to turn a screw, which would further reduction, and convert to linear motion (to replace cylinder)

Another option, if you are not using them already, could be to use multiple window motors.
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