Hi All,
Again; thanks VERY much for your help. I wish I could buy you a pint or 6...
I tried the suggestions both of you gave, but no joy. Here's some more info. This is to be added to what I said earlier.
-My kernel speed is 25KHz.
-The DROs and toolpath display work correctly (showing both axes moving even when one axis is not physically moving.)
-The X-axis is definitely changing to a different velocity and acceleration when the Y-axis stops working.
-If I quit Mach3 and restart, it usually takes 2 tries of clicking the desktop shortcut for Mach3 to start again. The 1st attempt seems to be ignored.
-I have found that sometimes the Y-axis continues to work but is considerably out of sync with the X-axis. IOW, if I try to draw my circle, the Y-axis doesn't start moving at all until the X-axis is many degrees into the circle.
-Several times, after successful tries drawing the circle, I could wait a few minutes and try again and the Y-axis had quit working.
-Once the problem showed up, Driver Test would report "Pulsing too fast" before Mach3 took over, and then "System Excellent" afterwards.
-The version I was running was 3.42.40. I installed 3.43.22 over the top of it.
-Each time the problem showed up, I could install the latest version and things would operate correctly for several tries, then goof again.
-I slowed down both axes to 125 IPM with low acceleration. My feed rate is set to 30.
-I have not tried uninstalling Mach3 completely and reinstalling. I'll try that next unless I get different advice.
Thanks again,
Tim