Author Topic: Changing stepper motors with more amp draw  (Read 204 times)

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Offline expressjoe

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Changing stepper motors with more amp draw
« on: December 10, 2018, 01:58:06 PM »
Hi all,

Very green to all of this,  so bear with me...

We replaced our green 3 amp stepper motors on the X axis with 5 amp stepper motors. Once running the machine started tapering X axis cuts. We are going to change all 4 motors on the table to the black 5 amp motors. Is there anything we need to change in Mach 3 to make for a smooth transition?  Both motors have 200 steps per rev. Running Windows 7 Ultimate.

Any help on this would be appreciated.

thanks in advance.

_

Offline RICH

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Re: Changing stepper motors with more amp draw
« Reply #1 on: December 11, 2018, 10:39:15 AM »
The steps per unit should be the same but I would still check the calibration after retuning the motors for max velocity and accel values.
Suggest you have a look at stepper info provided on the Geckodrive site. Your drives should be capable of the amp requirements.

RICH

Offline expressjoe

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Re: Changing stepper motors with more amp draw
« Reply #2 on: December 11, 2018, 10:57:36 AM »
Right on , will do , huge thanks Rich

Offline ger21

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Re: Changing stepper motors with more amp draw
« Reply #3 on: December 11, 2018, 11:37:37 AM »
If all you changed is the motors, then the new motors may actually have less torque at higher speeds, causing loss of position.
Do you have new drives, or are you setting the old drives to provide 5 amps to the motors?
Gerry

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Offline expressjoe

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Re: Changing stepper motors with more amp draw
« Reply #4 on: December 12, 2018, 11:56:33 AM »
I am using the old drives ( control boards?) for the new motors. they worked great for two weeks then started acting up.

Offline joeaverage

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Re: Changing stepper motors with more amp draw
« Reply #5 on: December 12, 2018, 12:36:00 PM »
Hi,
when a stepper motor de-accelerates (in fact any motor) it becomes a generator and pushes power back into the stepper drive, the amount of energy pushed
back into the drive is equal to the kinetic energy of the rotor and moving load.

Some drives handle the regeneration phase better than others....it sounds like your original drives were a bit weak.

Gecko's have the best reputation among CNC'ers  but Leadshine  AM822's also have a good reputation at about 1/2 -2/3 the price of a Gecko.

Craig
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     and I miss him!

Offline expressjoe

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Re: Changing stepper motors with more amp draw
« Reply #6 on: December 12, 2018, 02:29:06 PM »
Thanks Craig. I  got all 4 new motors working now, cables, motors and controllers working as normal , now test cuts.