>> Alan (who has a mangled hand due to incident with table saw).

I had a friend (now dead) who was a joiner. He had 4 reasonably
functional fingertips with a diagonal line running across them at
increasing distance from the end of the fingers - where the saw blade
took them off and the surgeons successfully put them back on again. He
did it a long long time ago - I'm surprised how well the "repair"
worked. I'm sure he'd have been a SawStop customer if they'd been
available some decades earlier :-).

I think SawStop is a great idea - and one day (almost) all saws will
be built  SOMETHING like that. But not until they make one with  a
detection system which is truly preemptive and makes it truly injury
free in normal use AND costs zilch if it false trips.
I think I'd have a fair prospect of making something now which comes
close to all that. (Read prior posts for some of that).
SawStop are going to have to have extremely broad and insightful
patents if they want to keep asking 8% royalties.


               Russell

For following, all rights reserved.
:-) - what rights those are vary with administration. NZ = none. US =
much AFAIK.

Some mix of some of:

- Pop back blade to withdraw from user at a velocity which rapidly
exceeds some design feed rate.
- Cover/guard which shrouds blade - with blade having withdrawn far
enough that finger is not impacted by closing guard.
- Rapid but non damaging braking.
- Non contact proximity sensing. "Those skilled in the art" [tm]  will
easily envisage many methods by which this may be achieved.
  Examples only include capacitance, optical (& electromagnetic in
general)  (eg camera hand position tracking, beam blocking,
reflective, doppler, TOF ranging, ...) , acoustic (much of as for
light), etc.
- Adding a signal to machine or user to enhance operation both in
isolation and wrt conductive materials. eg em signal capacitively
coupled from user to blade system. Increasing frequency allows
decreasing capacity coupling requirement until substantial non contact
proximity viable.
- Glove / hand / finger piece or mark or ring etc fir highly positive
tracking. More applicable in professional systems allowing very great
freedom of movement relative to open blade etc in exchange for
discipline of utilising the system.
- Extension to many or any other systems - saws, rotating and linear
action machinery, presses, stampers, guillotines and anything that
moves. Non contact proximity vvv desirable in some of these  - eg
large press - ir pressing your fingertips is unwise AND a hand in the
air may be well inside "maw" of machine when closing action starts.
Active hand etc (limb, head, body ...)  tracking allows extremely good
control. Two or more systems can track and vote to give near failsafe
operation. This is getting well away from SS ideas but is even more
useful.






                         Russell
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist