My company recently purchased a PCNC770 and I have noticed that doing retracts that have a g2 or g3 (helical retracts or g2/g3 in xz/yz plane) the z axis stalls for a short time, has an audible pop, but then continues to retract normally. I can't tell if the machine is actually completing the circular move or if it stalls for the entire move. This usually makes it lose its z position by about .005" so this is a problem when doing multiple cuts and retractions. This has only happened when doing circular moves while simultaneously moving in the positive z direction. The machine has no problem with circular or helical moves down into the material.
This isn't a big deal because I can still do straight retracts just fine so I can avoid doing these moves but I was wondering if anyone else has noticed a problem like this or has an idea what can cause this.