Recommended viewing - even if you never use a table or other power saw.

Auto stop saw protection - blade is stopped in about 1 millisecond
after contact with a conductive object - typically a finger.

I've seen videos of this before but this is by far the best.
Shown it in action with a sausage and then in fast and slow motion
from various views with a real finger - attached to its inventor. He
said it tickled.

Also show the mechanism in action in slow motion so you can see how it
stops, how fast, what happens to the blade and the energy and more.

            http://www.youtube.com/watch_popup?v=E3mzhvMgrLE&NR=1

Approach speed doesn't want to be "too fast".
If stopping time is say 1 ms then a 1 m/s feed rate - probably at the
upper likely end of the speed range, would result in ~= 1 mm
penetration into the cutting zone after 1st contact. At say 1200 RPM =
20 rps a blade will rotate 20/1000 = 1/50th of a turn or about 7
degrees in 1/1000 second. Scale up for faster RPM. Blades have from
about 20 teeth up or from about 18 degrees per tooth or less, So
stopping COULD be under 1 tooth time but may be several teeth and
perhaps several mm into the "target" worst case (fast feed, fast
blade, many teeth). So you'd expect you MAY get a nasty nick worst
case, as long as the system works OK.

Blade and brake die at each actuation so you don't want to try this too often.


               Russell






                     Russell McMahon


__________________________

Reference from Iona.
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