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-   Driving Mechanisms: Rack/pinion, gears, screws, belts & chains (http://www.mechmate.com/forums/forumdisplay.php?f=24)
-   -   Nema 42 Motor Size Question (http://www.mechmate.com/forums/showthread.php?t=2700)

15mgtar Thu 08 April 2010 02:25

Nema 42 Motor Size Question
 
I have bought the wrong motor size which are nema 42 size with 19mm shaft. Can you guys tell me which rack and pinion size to buy? I will be running mach3 in metric.

KenC Thu 08 April 2010 03:05

Ouch!
No worries, IMHO, you can still use Mod. 1 gear & rack, 24 teeth will be too small but 30teeth is big enough to cater 19mm shaft.
You need to mod the laser profile parts as well, motor mounting plates & carrier plates... Just a few that I cna think of.

15mgtar Thu 08 April 2010 03:22

Thank you Ken, where do you buy your rack from?

KenC Thu 08 April 2010 03:38

Deitech in Hong Kong. they are cheap but with some quality issue, which is still well worth my money.

bradm Thu 08 April 2010 05:12

15mgtar, you have several things to check/solve before proceeding with those motors.
- Shaft size / pinion size; if you'll be happy with the final gear ratio, what the torque will be.
- Redesign of the motor plates, also clearances of the motor positions, changes in the springs.
- Drivers capable of running those motors; power (voltage/amperage) to run those drivers, speeds of the motors, etc.

Bigger doesn't always work out -> think installing a tractor motor in a motorcycle.

You might find it easier and less expensive in the long run to return or E-Bay those motors and get another set.

KenC Thu 08 April 2010 05:18

I second Brad's advise. Unless you are competent with the necessary design alteration on your own.

Richards Thu 08 April 2010 08:15

Size 42 motors may be difficult to drive if you use Gecko stepper drivers. Big motors may require expensive electronics. Big motors often run much slower than smaller motors.

I agree with Brad and Ken. Rather than redesigning the machine, it would be easier to sell the motors and get some size 34 motors that better match the design.

MetalHead Thu 08 April 2010 18:58

Ditto on the sell and rebuy of Nema 34 motors.

Gerald D Thu 08 April 2010 21:14

Why a stepper motor should not be too big . . . .

15mgtar Fri 09 April 2010 02:03

I already have the motors and the drivers :( . the drivers runs on 110-220vac. Selling them would be a greater lost, I'm very low on money so I just have to stick with them.
I really don't know about shaft's size/pinion size (19mm/30???maybe 34 minimal?) and final gear ration so if you guys would kindly guide me through.

KenC Fri 09 April 2010 02:39

I recon not selling them will be a ever bigger lost.
Sell them & start over again.


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