On Oct 15, 6:50*pm, Stuart wrote:
In article ,
* wrote:

That's my point. Nobody else, so far, has addressed how they would
control the application of this "convenience brake", however
implemented. My pushbutton solution was rejected out of hand - but how
would any of the other suggested possibilities be implemented???

OK, here goes:

Pair of AC solenoids, one each side of the blade holding a brake pad away
from the blade, paralleled with feed to motor. When motor is powered
brakes are off, when motor switched off solenoids de-energise and springs
press pads against sides of blade. This is a "convenience" brake, no need
for great forces to be applied. Solenoids mounted on a sliding
arrangement, operated by a lever, which allows them to be moved out of the
way for blade changing.

See? I knew there was a rational suggestion around. Now put some
pincer articulated bicycle brake pads at the bottom of the blade and
presto! same results.
Now the aggressiveness of the relief cuts in the blade bodies could
make the pads wear out rather quickly.