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I have also revisited the clips. I have come away with the impression the primary goal of Mr. Butler is to sell or license his invention for the greatest amount of profit possible. Given current economy that could be a big job.

I agree with Dusty on the proximity censor. I guess I wonder if it's a light beam running on each plane surrounding the blade. If a finger breaks the plane the brake switch is triggered. No Dusty I know nothing of engineering. Although as recently proven am a klutz and capable of messing with proven engineering. Jim

fjimp wrote:I have also revisited the clips. I have come away with the impression the primary goal of Mr. Butler is to sell or license his invention for the greatest amount of profit possible. Given current economy that could be a big job.

I agree with Dusty on the proximity censor. I guess I wonder if it's a light beam running on each plane surrounding the blade. If a finger breaks the plane the brake switch is triggered. No Dusty I know nothing of engineering. Although as recently proven am a klutz and capable of messing with proven engineering. Jim

I am knot disagreeing, and I know nothing about how this works, but if a finger can do it, what stops the material being cut from doing it? I.e., doesn't the wood also break the light beam (or whatever)???

a1gutterman wrote:I am knot disagreeing, and I know nothing about how this works, but if a finger can do it, what stops the material being cut from doing it? I.e., doesn't the wood also break the light beam (or whatever)???

You are correct. My fantasy included a light beam that included the wood yet viewed another object of a different density or on another plane or level than the wood as undesirable thus activating. Awww shucks this is too complicated for a mere insurance guy. It must be nap time. JIM

fjimp wrote:You are correct. My fantasy included a light beam that included the wood yet viewed another object of a different density or on another plane or level than the wood as undesirable thus activating. Awww shucks this is too complicated for a mere insurance guy. It must be nap time. JIM

I don't think your nap time enters into this, Jim. I watched the video and he definitely said that the brake system was triggered by a proximity switch but I am at a lose to see how (without having the wood do the same thing). He referred to it as an "electronic fence" around the hazard zone.

dusty wrote:I don't think your nap time enters into this, Jim. I watched the video and he definitely said that the brake system was triggered by a proximity switch but I am at a lose to see how (without having the wood do the same thing). He referred to it as an "electronic fence" around the hazard zone.

Well Dusty there are members of my household that prefer the hair brained thoughts emanating from my slumber to pipe dreams from awake periods. Actually when I translated electric fence around hazard zone; it made sense to me that the fence doesn't include the table or the stock being cut but exactly what the name implies a zone immediately outside the perimeter of the blade. Would it be possible for such a zone to differentiate between the blade/wood/table and a foreign object IE a finger? Jim

[quote="fjimp"]Well Dusty there are members of my household that prefer the hair brained thoughts emanating from my slumber to pipe dreams from awake periods. Actually when I translated electric fence around hazard zone]

I don't know, Jim and Mister Butler is not sharing any trade secrets.

Dusty
Don't listen so much to what the guy says but rather watch closely what he does. First he always starts the dust collector. Notice how he is careful to keep the wood under the guard. Then watch how he places his finger on the wood near the bottom of the blade guard. Notice how he places it there, on side with his finger closing the gap between the wood and the guard.

My question is be it wind, sound, light or what ever how can it work for things like cutting wood that has a notch, knot or something where the wood has to introduced in such a way that wood isn't initially near the guard to start or finish the cut. I will guess that is chink in armour of this idea. The operational requirements are too confining for normal table saw use.

A controlled demo can make things look more fexible than they really are.

Perhaps it uses a similar technology as the SawStop. The ring around the saw guard has a current running through it. When human flesh (or something of similar moisture content) touches it, the current changes and the safety stop engages. You would still have the possibility of a "false positive", but the benefit over a SawStop would be no destruction to your table saw.

My guess is that it is a capacitance sensor driving a relay much like you see on some elevator buttons that activate without being depressed. It senses the capacitance of the human body and trips a relay to turn off the motor and activate the blade brake (perhaps even reverses the motor windings to stop the motor).

Easy enough to use a directional proximity sensor. I never saw a finger go under the guard, it simply got close to external side of the guard. All you'd need is a proximity sensor with a horizontal cutoff.

I would speculate that sawing a non-flat board could trigger the proximity sensor in that case. But that sort of cutting is quite uncommon on a table saw.

And it's my circular saw that has the motor brake. When you let go of the switch the motor becomes a generator and promptly stops itself, with the same sound as this unit.