I'll sort the wiring out but to be honest it's probably not what you want / think.

Because the Kress is thumb wheel controlled I just used the relay on Roy's Uniport board to power a sealed 3 pin socket that the kress just plugs in so the computer turns it on and off but i control the speed with the thumb wheel.

The air cooled one runs the same, inverter plugged into the socket and the speed controlled by the knob on the front of the inverter.

This can be fully computerised but I'll need to add a speed board.

Recently I have been fitting Roy's System 1 board with the plug in speed board that fits the system 4 setup.
very cost effective, work brilliantly.

If you needs Roy's boards http://www.diycnc.co.uk/html/cnc_boards.html
buy direct, they work out a lot cheaper.