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Author Topic: Stepper Speed on XYZ Router  (Read 2295 times)

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Stepper Speed on XYZ Router
« on: January 14, 2010, 04:21:56 AM »
The router table, steppers and drives were provided by foundertop, but a long time ago. I don't have any information on the drives, but I've reversed engineered a lot.

Motors do say 4A, 6.5 Nm. Ball screw pitch is approximately 0.175". In general, the fastest velocity I can get is about 35 ipm using a 10 accel. This is with 2000 to 2200 steps per inch.....I just got it close enough for now (less that 0.060" error out of 1"). I don't know what the 4 dip switches on the drives control, as it's written in chinese. The motor appears to be a hybrid stepper (i took it apart).

The router table is approximately 4'x4'. I haven't been able to find out much as to the voltage of the motors.

Speeds above the 35ipm cause the motor to resonate unstably. I changed the pulse duration on both the step and dir to 5uS, but it didn't improve. I've tried running Mach3 at 25KHz up to 65KHz, didn't improve it either.

Thank you,

Offline stirling

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Re: Stepper Speed on XYZ Router
« Reply #1 on: January 14, 2010, 05:15:19 AM »
The motor appears to be a hybrid stepper (i took it apart).

Not exactly sure what your question is but...

disassembly of a stepper motor will typically demagnetize the magnets to a point that the motor is useless until it has been properly remagnetized. With a few motors, the reduced energy will have little effect until the motor is under full load.
Re: Stepper Speed on XYZ Router
« Reply #2 on: January 14, 2010, 12:30:10 PM »
True enough regarding dis-assembly, but i had no choice (well, could have used the repair shop). Even though the motors had never been used in the 5-7 years it had sat...the Y axis was internally damaged, restricting rotation. When I opened it, there was a single laminate on the end that had come loose from the alignment pins. I carefully secured the laminate back on the guide pins.

The torque of this motor appears consistent with the X Axis (same motor size) so I doubt there is much measurable reduction in torque.

My question is, for a gantry router of this size with the 6.5Nm motors, what velocities have people been experiencing before stall? I don't know what the max RPM of this motor is (500? 1000?), but it only reaches about 200RPM before stalling. The motors are directly coupled to the ball screws and the spec's are in my first post in this thread. I would think it would move at near twice the velocity that it is, but I haven't ran any loading calculations. I could estimate the weight....friction would be tough?

I'm hoping that one of the DIP switches is not set to micro-step etc....and that changing it will improve....but I can't read chinese...LOL

I attached a picture of the gantry for size reference.
Re: Stepper Speed on XYZ Router
« Reply #3 on: January 14, 2010, 07:17:27 PM »
So I really think this could be a resonance problem, especially after reading the chronicles of information on this site. I need to try several things here:
1. Determine if micro or 1/8 stepping etc. is being applied
2. Provide damping from either a better coupling, or motor flywheel

In dissecting the problem, what relationship has anyone seen between the resonant frequency of the motor uncoupled, to the resonance coupled? I may try some testing tonight and compare the stall point coupled and uncoupled. In theory it should be much lower when coupled. I would expect it should reach at least 500RPM uncoupled.

Thank you,