Hey I have a problem with my lathe. I command M03 the main spindle to run up to a given rpm in MDI mode then I command M103 the sub-spindle to run at the same rpm. The problem is say I command a rpm of 1000 the main turns at that -+ a few revs...but the sub spindle is roughly 110 rpm above, that example is at 1000 rpm...other than 1000 rpm the varience changes drastically the higher in rpm I go the more the difference in rpm is, but it isnt consistent....now if I command M203 which is a main and sub synchronous forward rotation start the spindle speeds match perfectly....another issue I have is verifying my true spindle speeds, because I don't have any other tachometer other than the digital display on the CRT of the machine.

I doubt that it is an encoder issue because I would tend to think with an encoder problem the machine wouldn't work at all OR throw an alarm. I could suspect that one or both of my inverters are crapping out because on occasion when I turn on the main breaker one or both inverters don't come on. Lately they have been behaving in that manner....Hopefully someone has some ideas, because I am running out.

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