Way out of my depth

[JAZZCNC]

Mach3 cannot use Serial port for motion or I/O without special software/hardware. Do you mean parallel port.?

By far the easiset way to get this working will be to buy new BOB and wire servo drives directly.

However Mach3 using the parallel port won't provide high enough pulse rate to use those servo drives to there full potential and you'll have very limited speed. Even if you used whats called electronic gearing which will be built into the servo drives you'll still struggle with mach3 25khz default kernal speed. Even 45Khz which is about high has would advise running mach3 will need high electronic gearing ratio depending on servo encoder count.

To do this correctly with Mach3 you'll need Motion controller with at least 100Khz frequency. This KHz frequency also applies to any other controller as well because the number of pulses required for fully motor speed is dictated by the servo motor encoder count and Electronic gearing ratio if used.

Simple mach3 BOB will get you moving but it will be very slow and unreliable.

Edit: To work out the Frequency required for full Motor RPM without electronic gearing we would need to know the Encoder resolution or put another how many encoder counts per revolution. Any details on the encoder would help as there are several types of encoder.