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Author Topic: pulse? or step and direction control for spindle speed?  (Read 2398 times)

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pulse? or step and direction control for spindle speed?
« on: March 10, 2008, 07:07:36 PM »
i'm having trouble deciding what type of control to use for my spindle.   The spindle takes an analogue +/- 0-10VDC input.  Mach can output either a pulse width modulated signal (pwm) or step and direction control.  I cannot fathom which is better to use? or are they comparatively equals?   my spindle will run up to 3000 rpm, and has feedback from a tachy generator, I have a 1.4ghz pc running it.     There are a number of convertor cards/boards out there, some convert PWM to analogue volts, some convert step and direction to analogue volts,  any advice / opinions greatly appreciated  ;D 

Offline jimpinder

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Re: pulse? or step and direction control for spindle speed?
« Reply #1 on: March 11, 2008, 04:41:52 AM »
Get a digispeed (Australian) - look it up on the web - very good service by post - worked first time - you only need the cheaper one - the DC01.

This connects to the PWM output of the computer - and converts the signal directly to a voltage. The voltage depends on what voltage you want - so if you put 10 volts in, the output will be between 0 and 10 volts - depending on the pwm.

The two parts of the board are electrically isolated, so there is no danger of anything going wrong.
Only uses one output pin.
« Last Edit: March 11, 2008, 04:44:20 AM by jimpinder »
Not me driving the engine - I'm better looking.
Re: pulse? or step and direction control for spindle speed?
« Reply #2 on: March 11, 2008, 05:47:56 AM »
Different arrangement here, 4hp 3-phase motor driving the spindle through an expanding-sheave continuously variable drive system. A stepper driving the sheaves would be a tasty upgrade later in life, has anyone tried this before?