Lathe control, can it be done?

[medic29]

@JBornstein90

The only thing I could think of aside from a mechanical piggy-back system to move the pots would be something like a mosfet/opamp voltage controller or source that when fully on, produces the high end of the voltage range, and with a PWM signal generated by the arduino, the voltage can then be varied to its minimum range. This would be a new approach to the old tech. But would require atleast a few cups of coffee for damn sure. You said half is 250vDC. Since we know its 5hp, we can find out what the stall current is. You'd need to ask your electronics buddy if there are any "impedance matching requirements " i highly doubt it, but with old mechanical systems, upgrading to new-age controllers, you never know... If you're interested in seeing if this avenue is possible, I'm around!

The way this circuitry and how it controls the spindle speed is as follows, paraphrased obviously. When you start turning the first pot (50 k) from the CCW position 0 ohms. When increasing the resistance it increases the spindle speed from zero to about 1000 rpm, when the 50k pot is maxed out CW. Then the second pot (10K) begins to increase resistance which slowly weakens the field, but in doing so dramatically increases the spindle speed to 4000 rpm when maxed out full CW.

With how I understand this circuit works, I'm not sure how your suggestion would fit in. This is most likely due to my lack of knowledge. Does your suggestion replicate what the first pot does and what the second pot does....essentially increasing the resistance of the two circuits??