Z-axis overrun on G30?

[roamingdrone]

Hello! First, let me say - I'm a newbie - I just got my K2 machine setup for the first time this weekend, and I believe I've run into my first issue, after tuning everything.

My setup:

K2 29x14x5 router frame
Probotix Probostep motor kit w/ RF isolated breakout board
Porter Cable 892 router
Mach3 software

Lead screws are 0.1", and the steppers are 200 steps @ 2x microstepping. I configured all axis for 4000 steps/inch.

So, after some experimentation and a lot of reading of the documents, I got everything hooked up, including home switches on the k2. Everything is configured to do exactly as I would expect, and "calibration" on all axis always moves as far as I request it to. (As far as I can tell.)

However... I have an issue with the Z axis, primarily, after several G0 commands moving all three axis around, one out of every five G30 commands will result in the Z axis overshooting zero (heck, overshooting the home switch, too). If I put the Z (or any other axis) just positive of home, they all ref to home properly. This doesn't seem to happen with the "Go to Zero" button in mach3, only in MDI w/ G30. (Of course, it could happen, and I just haven't experienced it yet!)

I can't seem to find what's triggering the Z to overshoot, but on at least one occasion, it overshot enough for me to have to hit the E-stop before it burned up my motor.

Any advice or suggestions on how I can eliminate this problem?

Thanks very much!

!c

[ger21]

Try using G28 and set the G28 location in Config>Homing/Limits.

[roamingdrone]

Thanks - that command seems to imitate the "go to zero" button (or vice-versa). -- moving the Z axis first and then the X and Y, instead of all three at once like G30, and hasn't overrun run in a dozen or so tries.

!c