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john calendrille
02-05-2015, 01:23 PM
I am looking to achieve an output of 1.09 Nm torque and a velocity of 7.2 RPM on a shaft. I know I will need to create a compound gear train (MOD 0.4) but how do I choose a motor to start with?

jwatte
02-06-2015, 05:37 PM
Your power comes from your torque and RPM. You can model gearbox losses as a fixed percentage (10%?)
You can then model full-power versus 100%-duty-cycle as a factor 4 or 5. That gives you the minimum power to look for.
Once you find a motor you like in the right power range, you can then figure out what your gear train looks like by looking at the RPM value of the motor.

It turns out that 1.09 Nm running at 7.2 rpm is less than a watt of power, so almost anything will achieve your particular goals. 5W-or-better motors are cheap and plentiful. Lucky you!

john calendrille
02-07-2015, 01:52 PM
Your power comes from your torque and RPM. You can model gearbox losses as a fixed percentage (10%?)
You can then model full-power versus 100%-duty-cycle as a factor 4 or 5. That gives you the minimum power to look for.
Once you find a motor you like in the right power range, you can then figure out what your gear train looks like by looking at the RPM value of the motor.

It turns out that 1.09 Nm running at 7.2 rpm is less than a watt of power, so almost anything will achieve your particular goals. 5W-or-better motors are cheap and plentiful. Lucky you!

This is great information, Thank you! However I am very new to this technology (& this will be my first attempt at prototyping something like this) If you could break it down into laymen terms a bit that would help tremendously. I especially don't understand "model full-power versus 100%-duty-cycle as a factor 4 or 5". I am looking for a reversible motor that I can put a worm gear on (This is what others have done for my application, to eliminate any backlash, then add a compound spur gear train).

Thanks!