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Author Topic: Spindle speed not follwing correctly  (Read 1068 times)

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Spindle speed not follwing correctly
« on: January 03, 2013, 10:33:24 PM »
Hello all. I am new here so be patient please...

The problem I am facing is this...

My setup:
 I have a South Bend Magna turn 612 Lathe being controlled by mach 3 with a c11 bob, c3 index board, a kbpb-125 dc spindle contoller, and a c6 spindle speed contol board w a perm. magnet dc servo motor from SEM...

My problem:
I have been playing with this for awile now... I have everything hooked up and mach shows the correct speed in the true spindle speed box (verified with a digital tach)... Ive adjusted the pot on the c6 board to so that when i command a max spindle speed i get a voltage out of 10.8 volts and when i command mach to half the max spindle speed i get 5.4 volts... okay... not perfect yet though... the rpm at max rpm and half the max rpm is good and accurate and follows what a command  but anything inbetween half rpm and max rpm is incorrect and half max rpm and zero is incorrect... :-\ ... If I understand correctly if I do a max spindle speed figure and test the voltage then match the output at half max rpm to be exactly half of the max rpm voltage then everything inbetween should follow in tandem... Am I missing something here.... Ive read about the debounce but if im getting accurate readings in the true rpm i would think i am good in that aspect...

One thing I want to note is the kbpb controller calls for a voltage from 0-9 volts to control the spindle... I have read elsewhere that the voltage is somewhat irrevalent as when commanded rpms are commanded the rpm at half the max rpm shoud be exactly half of that at max rpm...

Anybody out there with some insight I would greatly appreciate it...