Motor noise

[m_c]

On the AC or DC side?
Have you got a diode to absorb the surge on the DC side from the relay being turned of?

[M250cnc]

Thanks, the motor noise manifests itself as glitches in Mach3

The way my relay is switched is as follows i use a solid state relay package that is operated by Mach3 via a bob

This operates the bigger 240v 10a relay. I am switching the live and the neutral.

My pump motor is single phase as was the spindle motor when i got the machine, it was run from a 13a plug.

As i said in my post it only seems to happen at switch off.

The coolant motor is maybe 20+ years old the spindle motor in new along with the VFD and they are quality makes.

Phil