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Author Topic: Setting up a Motor/Driver for high torque  (Read 2518 times)

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Setting up a Motor/Driver for high torque
« on: July 24, 2013, 11:57:02 AM »
Hi, I have a 4 axis CNC machine with a spindle running on a profile. I have added a fixture with it's own motor/driver that I want to run on it's own profile. It is never required to run with any of the other axis or spindle at the same time. I do not need to worry about speed, it is mostly to run to programmed positions when an input is actuated, and set an output when it reaches the position. The torque required to drive the fixture is quite high and unknown. All I know is that the motor gets very hot as it runs, and I don't want to 'fry' it or the driver. My components are:

Driver - 1.4A -5.6A (dip switch set), 400 - 25000 pulse/rev (dip switch set)
Motor - Nema 23 565 oz/in (4NM), 8 wire, 4A wired parallel, 2A wired series
Gear reducer 12:1 (to reduce the torque)

My question is, what sort of settings should I be looking at on the driver? I have my motor wired Bipolar Series, is this the best?
I can work on my Motor Tuning when I know everything else is optimised.

I hope this combination works as I really don't want to purchase a larger motor (Nema 34) as I will have to also purchase a new gear reducer, driver, and possibly a power supply.

Thanks, Barry.

Offline stirling

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Re: Setting up a Motor/Driver for high torque
« Reply #1 on: July 24, 2013, 12:17:49 PM »
As you're not concerned with speed, series is correct for highest torque. Drives current limiting should be set to match your series current so 2A as stated. (Never over current a stepper). Steps/rev should be 2000. BTW I assume you mean your 12:1 gear reducer INCREASES torque (as well as resolution of course).

Ian

EDIT: BTW moved this to general - you'll get more responses there. (Don't know why we have this FAQ forum really)
« Last Edit: July 24, 2013, 12:23:44 PM by stirling »
Re: Setting up a Motor/Driver for high torque
« Reply #2 on: July 24, 2013, 12:54:14 PM »
Hi Ian, thanks for the reply and moving this to the General forum.

The gear reducer actually reduces the torque. It takes 12 revolutions of the motor to drive the output shaft 1 revolution.

Barry.

Offline Hood

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Re: Setting up a Motor/Driver for high torque
« Reply #3 on: July 24, 2013, 01:42:46 PM »
That will increase the torque by 12 :)
Hood
Re: Setting up a Motor/Driver for high torque
« Reply #4 on: July 24, 2013, 02:08:14 PM »
Hi Hood, I don't know if my description is confusing, but my motor torque requirement decreases. If I manually take the gear reducer and spin the shaft at the motor end, it is pretty free and the load end rotates slowly. If I do the same with the load end shaft and spin it, it's a lot harder to spin, but the motor end rotates faster. I would use the gear reducer the opposite way if I didn't have an issue with torque and wanted my load to spin 12 times faster than my motor. No?

Barry.

Offline Hood

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Re: Setting up a Motor/Driver for high torque
« Reply #5 on: July 24, 2013, 02:20:29 PM »
If you have your motor on the input and it takes 12 turns of the motor to turn the output then you get a torque increase of 12x.
If you had it the other way about, ie you hooked up so 1 turn of motor equals 12 turns of  output then you would be reducing the torque by 12.


So yes for a given output torque requirement if connecting per the first method then your motors torque requirement would be less :)


Hood
Re: Setting up a Motor/Driver for high torque
« Reply #6 on: July 24, 2013, 02:42:46 PM »
Thanks Hood, I think we were saying the same looking from 2 different angles. I was saying that the motor torque REQUIREMENT decreased by 12, while you were saying that the motor torque CAPABILITY increased by 12. :-)

Offline Hood

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Re: Setting up a Motor/Driver for high torque
« Reply #7 on: July 24, 2013, 02:48:04 PM »
Yes, if you had said

Gear reducer 12:1 (to reduce the torque required) then I would have known what you meant :)

Hood