Hello, I have an old Bridgeport J head with a Prototrak retrofit that I am working on retrofitting to Mach3. I want to use a VFD for speed control as well as for on/off and fwd/rev. Do any of you have any advice or reccomendation for a specific brand/type? If possible, I would like to be able to use it with Mach as well when I get it retrofitted.

Thanks,
Scott

I don't particularly understand your question, it is too vague.
Do I assume that all your axis are set up , and the only thing your are bothered about is the spindle speed controller.

If that is the case, Mach 3 provides two different systems, you can either have step.dir control, or PWM control.
My system uses PWM. The output signals from Mach 3 provide a PWM signal on one wire, with M3 and M4 signals on two other wires. I use the PWM signal with a Digispeed converter, which provides a voltage signal to an Omron Inverter.

I assume your Bridgeport has a three phase motor, otherwise you will have to change it, since single phase cannot be controlled for speed. To control it you will need some form of inverter, my Omron came free so that is what I used, together with the 1 3/4HP three phase motor to replace my 1HP single phase motor. The system is such that speed of the spindle is controlled to + - 2 rpm. However, most Inverter systems are probably as good as the Omron, so what can you get on the market.

The one thing is, if changing the motor, fit one about twice the power of your original, otherwise you will loose too much power on the speed inverter.

Hope this helps. If  I have got on the wrong tack come back.