Laser sight question.

[Shield Arc]

Probably about to make a fool of myself. I Googled it but came up with nothing. My 14-year old grandson came by yesterday to show me a project he did in Jr. high wood shop. He was saying during shop orientation the shop teacher was talking about a safety class he went to where they had laser sights on the saws, if you placed your hand under the laser sight the saw would not turn on!
Anybody ever hear of this? Or is my grandson pulling papa's leg?:laughing:

 

[uglyboywith11fingers]

at first thought, maybe a safety feature for equipment in school shops ???
on second thought, how can the sensor distinguish between a hand and a piece of lumber ?

Pete

 

[Shield Arc]

how can the sensor distinguish between a hand and a piece of lumber ?

Boy you got me! But I do good to turn this computer on in the morning. :laughing:

 

[J_J]

Don't know how it works, but it does say it gives a warning.

The laser saw guide provides an instant warning should the operators hand or fingers be in danger.

Laser Us Inc - Laser Saw Guides

Some laser saws activate when the saw is running as it is mounted on the arbor.

Other laser pointers use a switch to turn the laser on /off.

I believe the safety part is that if you see the laser is on your hand, you,using common sense will not pull /let down the saw.

Here is a capacitive type safety saw.

http://www.youtube.com/watch?feature=player_detailpage&v=esnQwVZOrUU

http://www.sawstop.com/how-it-works/

 

[uglyboywith11fingers]

I imagine you still need to have your eyes open to see the red line across your fingers...

Pete

 

[texasjohn]

Interesting...how does it work

Motion detection....nope, it's mounted on the saw blade itself and saw dust moves

Heat detection....nope, blade heats up in operation, wouldn't it stop??

And, all at an affordable price!

 

[Shield Arc]

JJ he did say something about testing the laser with a hot dog.

 

[Scooby074]

In finger safe tablesaws, Sawstop is the dominant technology. He uses a combination of capacitance sensors and a brake cartridge to drop the saw. He (Gass the company founder) the guy that did the hotdog tests.

There are some competing technologies, a new one, and possibly the one your grandson is talking about is called Whirlwind. Whirlwind Tool Patents Pending Saw Safety Technology. His system is based conductive plastic on the guard, sort of like a touch lamp, so he can get around Gass's patents. Problem is, the guard needs to be installed for the system to work. That is a major inconvienance for some types of cuts. There are a ring of LED's around the blade guard, perhaps that's what your gandson saw? AFAIK, Whirlwind is only a prototype.

The bigger problem is, Gass has SO MANY (unjust IMHO) patents on finger safe saws that its virtually impossible for a competitor to get his foot in the door. He's a patent lawyer by trade and has anything remotely related to his system locked up tight. Matter of fact, he was lobbying California to MANDATE his safe saws and have traditional saws declared "illegal" and unsafe. In the woodworking world, there is not a whole lot of love for Gass.

Whirlwind:

 

[Scotty Dive]

yup...saw stop...watch this one....the designer puts his own finger to show how it works...

Time Warp - SawStop - Snotr

 

[NorTracNY]

The reflectance and scatter off of skin is very different compared to a piece of word.

 

[crazyal]

Never looking into how they work but we have laser curtains at work that stop any moving equipment if a person enters the restricted space. They get used anywhere there's contact between people and robots or other moving machinery. For example the silicon wafers get placed in a boat that holds 25 and that gets placed in a box while being moved from one location to another. Often times people will either place (or pick up) the boxes on a platform. The laser curtain will prevent the robot from touching the box as long as there's an arm or hand in the danger area. Otherwise they just have shields in place. Sets off all sorts of alarms so once people set the alarm off once they learn not to cross the line. Of course there's also the mandatory daily testing of the system. Years ago we had someone seriously hurt because someone defeated the system while working on it and accidentally forgot to reset it.

 

[Danno1]

The reflectance and scatter off of skin is very different compared to a piece of word.

I bet it is!!!


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[NorTracNY]

I bet it is!!!


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Sorry, I guess I wasn't clear. As an optical person, that is how I would imagine creating this type of safety device. You have a laser and detector(s) which would have calibration to know the difference between a piece of wood and human skin. I'd still be concerned about getting the accuracy good enough though.

 

[etcallhome]

I forget the name of the table saw , but if finger is detected near or about to hit blade , saw blade quits turning NOW... This came out about 3-5 yrs ago if I remember correctly. Sure beats loosing your fingers , a hand, or maybe your parts of your body if you fell across a running table saw blade.

 

[wyeguy]

Sawstop uses a small electrical current to detect flesh. It might cause a tiny nip, but fires a cartridge to drive a metal stop into the blade so fast, it won't draw blood. It destroys the blade, and is a one shot cartridge (you can replace), but look Ma! Ten fingers! I've heard that guys cutting fiberglass can cause the system to fire. Don't know nothin about laser systems.

 

[Danno1]

Sawstop uses a small electrical current to detect flesh. It might cause a tiny nip, but fires a cartridge to drive a metal stop into the blade so fast, it won't draw blood. It destroys the blade, and is a one shot cartridge (you can replace), but look Ma! Ten fingers! I've heard that guys cutting fiberglass can cause the system to fire. Don't know nothin about laser systems.

I believe Sawstop can also be triggered by wet PT wood.

If you go to the Fine Woodworking website you can read for hours about SS, the inventor ( a laywer!), and a recent lawsuit.



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[schmism]

I believe Sawstop can also be triggered by wet PT wood.

If you go to the Fine Woodworking website you can read for hours about SS, the inventor ( a laywer!), and a recent lawsuit.

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so post the link and keep us have having to search for it!

 

[Danno1]

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