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General Mach Discussion / Mach3 Output For DC Motor Control
« on: July 31, 2013, 11:16:53 AM »
Hello Everyone...I'm new here today.
I have a Bridgeport style mill (48" table) with a Leeson 90volt DC motor attached (no speed control other than pulleys)
I plan to convert this mill to CNC shortly, using Mach3 as control software.
I'm well versed in digital and analog electronics, as well as computer science and programming ( basic, C, C++, visual basic )
Sorry, no bragging here, but I don't want anyone to hold back tech info.
My main question is with spindle speed control.
While reading other posts, I notice that with Pusle Width Modulation control of DC motors, most users on this site
convert the PWM output of Mach3 to a 0 - 10 volt analog dc voltage and use it to control a PWM DC motor driver board.
I don't get it. Why not just drive a hefty Mosfet ( like a irf260n (50 amps @ 200 volts) ) directly from the Mach3 output pin? (through a suitable FET driver chip such as a 4420CN, and an opto-isolator of course )
Why go from PWM to Analog and back to PWM again to drive the motor?
Am I missing something?
Thanks!
I have a Bridgeport style mill (48" table) with a Leeson 90volt DC motor attached (no speed control other than pulleys)
I plan to convert this mill to CNC shortly, using Mach3 as control software.
I'm well versed in digital and analog electronics, as well as computer science and programming ( basic, C, C++, visual basic )
Sorry, no bragging here, but I don't want anyone to hold back tech info.
My main question is with spindle speed control.
While reading other posts, I notice that with Pusle Width Modulation control of DC motors, most users on this site
convert the PWM output of Mach3 to a 0 - 10 volt analog dc voltage and use it to control a PWM DC motor driver board.
I don't get it. Why not just drive a hefty Mosfet ( like a irf260n (50 amps @ 200 volts) ) directly from the Mach3 output pin? (through a suitable FET driver chip such as a 4420CN, and an opto-isolator of course )
Why go from PWM to Analog and back to PWM again to drive the motor?
Am I missing something?
Thanks!