Identify and document gearmotors

[jasonwebb]

Gearmotors used for shoulder, elbow, wrist (bend), and base

• Manufacturer = Pittman
• Model = GM9413G937-R3
• Voltage = 24 VDC
• Current rating = needs to be tested
• Torque rating = unknown
• Gear reduction ratio = 127.7:1

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[jasonwebb]

Looks like the motor on the wrist joint is a little bit smaller than the others, so it should be documented.

Also I have not looked inside the base yet, and there may be a different motor in there too. Will investigate.

[jasonwebb]

Have confirmed that the motor in the base is the same used for the shoulder, elbow, and wrist (bend).

[jasonwebb]

Located the datasheet for the gearmotors, which contains all the information I needed: https://github.com/jasonwebb/loogie-robot-arm/blob/master/docs/datasheets/DC%20gearmotor%20(large)%20-%20GM9413-1.pdf

Specifically it contained the values from the original post I was missing:

• Current rating = 1.4A (max)
• Torque = 15 oz-in continuous, 36 oz-in stall

Only discrepancy is that the datasheet says these are 12V motors, not 24V.

I tested the motors at both 12V and 24V using my benchtop power supply and found the current draw under load to be close to the stated spec.

[jasonwebb]

The motor use for the rotational axis of the wrist is a bit smaller than the other motors. Here are the specs I've been able to identify:

• Manufacturer = Pittman
• Model = GM8712F255-R2
• Voltage = 24VDC
• Current rating = 1.76A (max)
• Torque = 16 oz-in (continuous), 72 oz-in (stall)
• Gear reduction ratio = 60.5:1
• Datasheet = https://github.com/jasonwebb/loogie-robot-arm/blob/master/docs/datasheets/DC%20gearmotor%20(small)%20-%20GM8712-21.pdf

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