I want a spindle lock so I can prevent any shift on the milling spindle when I do finishing cuts.

Pneumatic seemed the best bet for CNC control so I just bought a ram (32mm piston, 5mm stroke) and a solenoid valve off fleabay.

Started designing complicated lever mechanisms to tighten the spindle lock bolt, then it occured to me it could be totally simple.

If I drill a clearance hole through one end of an iron bar.

Put it under the spindle lock bolt head, as you would a washer.

Put the ram so it tries to lift the other end and tilt the iron bar "washer".

Surely that would lock the spindle with lots of leverage, be totally adjustable and I can still lock the spindle manually if I feel like it.

So why won't it work? Nothing can be that simple :D