What @Muzzer said,

I have a Boxford VMC260 and is has homing switches but no limit switches. When you startup you home the 3 axis, if configured correctly it will know the extent of your axis travel

Caveat, I'm new to all this and still finding my way around

If you are looking to convert your Harrison mill to CNC, this might be worth a read https://www.mig-welding.co.uk/forum/...achine.109112/