SmoothStepper-Enquiry

[leMaitre777]

Hi I`m currently using a parallel port BOB with my CNC system but I`m having major resonance problems with my x axis at a certain speed. I Tried increasing the micro stepping and the output/kernel frequency in mach but to no per-vial, it still shakes crazy at that speed. This is only one of my problems the second I have is with Mach3 just randomly going input emergency mode, I believe this is due to induced emf in my input cables but they are shielded and grounded, oh yeah also increase the debounce time to 2000.

This leads me to the Smooth Stepper, could it possibly cure both these problems or at least reduce their effect?

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[jfong]

Can you give us more info in the CNC, type of stepper drives etc.

Most stepper motor resonance issues are usually taken care of by using good anti-resonance drives like the ones that Geckodrive sells.

[leMaitre777]

Hi, well yeah these are pretty cheap drivers and motors.

Drive : http://www.wantmotor.com/ProductsView.asp?id=271&pid=82
Stepper : http://www.wantmotor.com/ProductsView.asp?id=173&pid=80
I dont believe my exact motor is actually list there but is a of that model range. Mine just the 7Nm spec and 6.8 all tough it could be that one.

These motors had resonance at that speed even before I installed on the machine structure, just free turning on a flat surface they would literary bounce at certain (only one small range) pps.

[jfong]

I'm not familiar with that driver and webpage isn't really specific if it has any anti-resonance capability.

Depending on the motor, resonance is usually around 300-500rpm, which leads to motor stalling.

If it is resonance, I don't think a smoothstepper will fix the issue at all.

[leMaitre777]

It behaves exactly like resonance.>> It only occurs at the resonance speed which I can work out because its exactly at 20% jogging speed but I'm not at the CNC setup today will check tomorrow but my feeling is its at about 40-70rpm which is a really slow speed. Every time the axis goes to full speed it will have to go through that resonance point, it will eventually which wont be that long (few operating hours) destroy the motor bearings.

I will also contact the supplier on Monday and ask him if this is a common occurrence, because they usually sell this motor and driver as pair... (puzzled face)

[leMaitre777]

Just had a quick look my max speed is 195 RPM
Therefore resonance at 20% jogging speed gives me 39 RPM
The micro stepping on the driver is set to 3500 pulses per revolution

[jfong]

Which CNC do you have and pitch of your leadscrew/ballscrew? 39rpm seems low for stepper motor resonance but you do have large high torque steppers.

Did you try swapping motors between axis. It could just be a faulty stepper or even a bad driver.

[leMaitre777]

I have two that run in parallel on a rack.
It looks better a present all neat and connected but you get the idea. Its a big drilling rig I build. yes the speed is low because I get 46mm/rev [1.8in/rev] of the motor.

I get the exact same resonance on both motors which have separate drives of which the one is slaved in mach3 so I doubt its a faulty motor or drive because then it will have to be that either both the motors or drives are bad.

[jfong]

The only thing I can suggest now is to get some geckodrive 203v drives. They have a adjustment for low speed stepper motors. It makes them run smoother. It's a expensive upgrade but it will probably solve your resonance issue.

[leMaitre777]

Well thank you for you input into this matter. You answered my question and possibly saved me money. 2x 203v drives are about the same price as a smooth stepper and I do agree that changing the drives would have the best results.

[jfong]

To make sure it isn't a computer problem, I would wipe out the drive and reinstall WindowsXP 32bit and then Mach3.