Spindle control

Dinuka_Shehan wrote:

Pin 17 use as spindle output then connect pin 17 to common pin of 5v bob relay.5v relay switch on another 5v external relay module.
external relay module switch the 3 phase motor contactor coil.

What is the rating of the relay on the BoB? Most of the ones I have seen are capable of switching 230V AC directly. In fact they seem to be rated to power single-phase spindles such as routers directly. (240V / 10A)
So you probably don't need the extra relay between the BoB and the 3-phase contactor.