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Author Topic: CNC Router "Stutters/Loses Position" on Faster Feed Rates  (Read 2115 times)

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Offline ger21

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Re: CNC Router "Stutters/Loses Position" on Faster Feed Rates
« Reply #10 on: November 28, 2017, 10:19:48 PM »
If your drive is set to 400 steps/rev, that would mean your screws have a 1 mm pitch.

Does the machine move the correct distance?

With 1mm pitch screws, 30ipm would be about 750 rpm, which you'd be unlikely to get with only 24V.

Also, you shouldn't have it set to 4 amps with a 2.8amp motor, as it'll damage the motor.


Gerry

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Re: CNC Router "Stutters/Loses Position" on Faster Feed Rates
« Reply #11 on: November 28, 2017, 10:35:40 PM »
It is a 8mm pitch. I've confirmed this with the manufacturer. I could be wrong on the 400 steps/rev (is this the same as pulse/rev?).

Regardless, in your experience, what conditions would cause a skipping/pulsing effect on a jog, but diminish at lower speeds?
Re: CNC Router "Stutters/Loses Position" on Faster Feed Rates
« Reply #12 on: November 28, 2017, 10:58:22 PM »
Hi,
I think ger21 is right, without the correct steps per unit you could be demanding that your stepper go way too fast and it will
fail to do so and quite probably give you the symptoms you describe.

You cannot guess about these things, if its not right, everything else is rubbish.

Microstepping is used because it results in smoother motion of the stepper motor. Most people  use '8 micro steps' or maybe '16
microsteps'. You could use even more if you wish but then Mach may not be fast enough to drive the machine to high speeds.
As a consequence 8  or 16 microsteps is a good compromise. It sound like your driver is set to '2 microsteps'. I really want you
to study the manual to resolve this. I would set the switches to '8 micro steps' which is the same as 1600 pulse/rev or
1600 steps/rev.

Note that is steps per rev, so if the machine moves 8mm per revolution of the screw then the steps per mm would be 1600/8
or 200 steps per mm, or in inches, 200 x 25.4= 5080 steps per inch.

What are the native units of your setup? Look under Config/Select Native Units....you can use either but once you choose it
then leave it alone. If you want to run some Gcode in inches use G20 or in mm use G21, don't fiddle with the native units.

Craig
My wife left with my best friend...
     and I miss him!
Re: CNC Router "Stutters/Loses Position" on Faster Feed Rates
« Reply #13 on: November 28, 2017, 11:37:36 PM »
Do you think having too many steps specified in Mach3 (ie 10,000+) will result in these conditions? Best to keep in the low thousand range?

I guess I am having trouble understanding why the such wide range in microsteps on the driver when you can do your speed manipulation in Mach3?
Re: CNC Router "Stutters/Loses Position" on Faster Feed Rates
« Reply #14 on: November 29, 2017, 12:33:12 AM »
Hi,
there is ONE right number for your machine...it is the number of pulses that Mach has to issue to get the axis to move one unit, whatever units you
choose. If you put the wrong number, say 10000, when your machine  is actually 5080 Mach will issue 10000 pulses and you expect the machine to move one
inch but it in fact moves closer to two inches.

What is the native units of your machine?

Craig
My wife left with my best friend...
     and I miss him!