Re: [CAD_CAM_EDM_DRO] Re: Bridgeport motor question

Tim Leech wrote:

>How do you control the speed? I'm hoping to do it eventually via the
>software, & will be grateful for any pointers on that.
>
>

Most of the newer VFDs have provision for a manual pot or a 0-10 V
external signal to control speed. Check the specs, however, as the analog
input is an extra-cost option on some models.

Once you have a VFD that accepts an analog voltage, then you need software
in the CNC program to handle Snnnn commands in the G-code and
convert that to an analog voltage. Mach1 and Mach2 apparently do this
with software-generated PWM waveforms which you just average with
a resistor and capacitor. You'd need an op amp circuit to raise the maximum
voltage level to 10 V. Using EMC with the Servo-to-Go card or my
PPMC board set you can get a 0-10 V output from an unused DAC channel
to control spindle speed.

Jon