Success!!!!!
The C-37 single relay board from cnc4pc.com is an excellent little unit.
No 10k pull-up was necessary!
Pulled 5 v off the HobbyCNC board to power it, and attached the input to pin 14.
Wired the vac in on the NO pins of the relay.
Didn't need an extra in-line switch as the vac already has one!
Sweet!!!!!
Thanks to every for their suggestions!
The idea of turning something off as an alarm was a stroke of genius!
Many thanks to all who participated!