VFD spindle control safety

[magicniner]

This is like a health and safety thread on a model engineering site! ;-)

Commercial CNC machines rely on the spindle motor drive, with a suitable signal from the controller, to prevent the spindle starting up whilst changing tools, that works, failure to understand why will lead you to think you need breakers and stuff between the motor & VFD when you don't.

If you have a decent VFD it has the facility for an E-Stop data input, this will suffice on equipment of a reasonable quality.

[Kitwn]

A-Camera,
I appreciate that a proper procedure for stopping and isolation protects the VFD. My concern would be the occasional operator error, possibly starting the VFD before closing the contactor which is why I suggested the back-contact interlock to prevent the VFD from operating with the contactor open. This ties in with my earlier comments about the 8 second delay etc. These spindles are a big investment for a hobbyist and anything you can reasonably do to prevent one of those potentially expensive "Oooops!" moments is worth considering.