Alright guys, I need some help, and I'm sure this group can make short work of my problem.

In short my Y axis is stalling during rapid moves. The axis stops moving and the stepper emits a high pitch whine. It doesn't happen on every move but at what seems like random intervals. I did a bit of trouble shooting yesterday and have listed my findings and machine specs below. Let me know what you think. I need to get this problem solved and preserve the rapid speed of the machine if possible.

Machine Specs (pic attached)



The Y axis rides on V-bearings and V-rails (hardened steel) from Pacific Bearing.
The drive system is the CNC router parts belt drive (3:1 1" diameter pinion) mated to racks from Moore Gear (20 DP).
I am using a 425 oz stepper from Keling Inc. (KL23H286-20-8B) powered by their 24V power supply, the KL-4030 stepper drive with 1/8 steps and the C33 multi function router board from CNC 4PC.
I am using Mach3, SPI are approx 1500, accel 25, rapid speed 500 ipm.

Troubleshooting and testing

The first test was to confirm that the Y axis was not binding. I checked the preload on the V bearings and everything seemed fine. I then disengaged the pinion from the rack and moved the Y axis back and forth. It moves very smoothly and does not take much effort at all to get it moving.

The next test was jogging the Y axis back and forth using Mach3. The Y axis moves smoothly and quickly, but occasionally stalls while in motion. The axis stops and the stepper emits a high pitch whine.

The third test was to check for resonance. I removed the dampener from my Z axis and placed it on the Y axis motor. I jogged the Y axis with Mach3 and got the same results as before.

Test number 4 was performed with G code. I wrote a quick test program of a series of G0 moves back and forth along the Y axis using random distances Whit an M47 command to keep the program looping. The motor did not stall on it's own, but I was able to get it to stall sometimes by applying resistance to the Y axis, but not every time. I would apply pressure with my finger against the side of the Y axis, as if I were trying to stop it from moving. Some of the time it would not stop and in fact had a considerable amount of force pushing against my finger. Other times it would stall immediately with almost no pressure from my at all.

I tried varying the engagement pressure of the pinion by adjusting the turnbuckle, but it had no effect.

I do not have a torque curve for the stepper. Does anyone have one for this particular motor?

Any idea's what might be causing this?

Thanks,
J