I am using the Low Cost CNC 4 axis stepper system from the guys in Australia to run a CNC router and I am having trouble sorting out an issue with my motor calibration in Mach 2.  Or at least I think it's a calibration issue. It seams that my stepper motors sometime (unpredictably) lock up when a rapid movement command is initiated.  It will run fine for long periods but then all of a sudden a motor freezes and makes awful sounds.  I have had it happen individually on all three axis on separate occasions. Can anyone provide suggestions or offer advice on how to trouble shoot this?

Steve

Could you please run a driver test and tell me what you see?

Hi Champion,

Thanks for your reply.  Here is what I found during the OCX Driver Test

Interupt Used = 0
Pulse per Second = varying between 24394 to 24389
CPU Speed = 1694
time between pulses = mean is at about 40 but fluctuates between 20 and 60.

Is this what you were looking for?

Steve

sorry I meant to adress my last post to Barker806

That looks good...

Barker806,

When you say it looks good do you mean that the CPU and Mach 2 are working properly? Are there any other ways for me to trouble shoot this problem?

Do you think it might be an issue with the motor tuning settings? The setup I used for each axis is as follows:

Velocity 0.5
Units / sec^2 = 4
Steps per unit = 20000
Kernel speed set at 35000 Hz

Theorectically, with the system flat out the maximum Velocity should be 1.75 inches/second or 105 inches per minute.  To be conservative I limit the rapid movements to 30 IPM.  Do you have any thoughts on this?

Steve

OKay try running the system at 25KHz and set you step to 5us under the motor tuning. If you have trouble with this please post you your XML and I can do it for you.

It will run fine for long periods but then all of a sudden a motor freezes and makes awful sounds.  I have had it happen individually on all three axis on separate occasions. Can anyone provide suggestions or offer advice on how to trouble shoot this?

Steve

That is a classic step motor Stall.   You are probably trying to run them faster than they are able to.

Tell us about your setup.   Are the motors on the machine and driving a load?   Steppers on the bench unloaded will nearly always stall at a lower rpm than when under load.

Also steppers prefer to have some damping between them and the load.   Never use rigid couplings.   I tend to use fenner couplings with a nitrile insert acting as a damper.

Wayne....

Bryan, I will give your suggestion a try in the morning.  Can you explain how kernel speed cause a motor to stall?  I appreciate all your input.

Wayne, The motors are attached to the CNC router and dirve ballscrews using timing belts with pulleys and a 2:1 ratio.

Steve

Wayne,

I attached the specs on the stepper motors. I have size 34 P/N PF4913A-05 on all three axis.

Steve