I was having a similar thought. Instead of the magnetic base with the
rotating switch, I was thinking along the lines of an electromagnet.
Attaching the featherboard would be similar to the above .pdf approach.
Simply run around 1/2 amp at 12V DC through the magnet and it will
hold the featherboard down with 120-150 lbs!! No plastic levers to
rotate and no magnetic switches to turn - just flip a switch. The
downside is the need for the power supply and wires running all over
the place (and into the blade!!!). Also, these magnets are around $40
for the 120 lb version. Just a thought. PS - I looked into building a
step-up power supply to generate the 12V from a single (or couple) of
rechargable nicads, but it's not as simple as I wish. This would
eliminate the need for the external power supply and all the wires...