It always happens in the acceleration phase, toward the end, when traveling a very short distance, as when I am drilling a series of holes, the Y axis freezes, thus losing its steps.  It's random. For example, it cut one piece fine, and then on the second piece, it froze.  I homed it, and then sent it back with a "start from here" command, and it worked fine and completed two separate pieces.

My acceleration is only at 4 ipm, with a top velocity of 70ipm and the motors are at a 1/2 step. ( motors are Kelings 425 oz/in).
I am running the job only between 26-36 in/m feed.

It's the randomness that is puzzling me as well as the fact that it's always in the y axis when it's doing repetitive operations such as drilling a series of holes 1/2" apart. 

I am cutting MDF, using 1/4" bit and depths of no more than .100 at a time. 

Can it be that the acceleration of the steppers is set too low? Or is it in the code?

I know I've got plenty of power( 80volt ps) and there's plenty of current feeding them( 3.17amps).

tony

If X & Y axis are identical then swap them and see if it does it with the X axis. If so, lower the max velocity and maybe increase the accel some ....say 50 ipm max velocity and 5 accel.  

The G0 are rapid moves and as such the axis will try to move at the lowest max velocity setting of a combined axis move, so if they are both set at 70 ipm, with no head room allowed, then you will probably miss steps at random.

RICH