After reading Robin Hewitt's post about his Warco mill drill conversion I started wondering if there is an easy way to incorporate a z-axis lock into my mill / drill conversion, I've got a Rong Fu that looks identical to the Warco.

Rather than using an electrovalve and pneumatic set up, as Robin has done, is it possible to use a shot bolt solenoid fitted to press directly against the spindle sleeve?

Ideally I would like to control the solenoid via a diycnc.com system 4 board, which has two spare outputs, one of which I currently intend to use for a motor on/off relay signal. As an alternative to tying up the other board output I'm thinking that it might be possible to trigger the solenoid to only activate when the z-axis is inactive (probably best to ask Roy at diycnc about that one)?