So everyone that has an accident is an idiot? Safety features are not
I see it as reducing the odds that even a careful person may still have
a very bad accident as a result of moving a bit too fast, being a bit
too tired, being distracted and just the wrong time, etc. All safety
features are an effort to reduce these odds, from back up chutes for
skydivers to inflatable buoyancy devices for scuba divers. This is
prudence, not idiot proofing.
HUH? The saw does not have to be turnrd on for the blade to be spinning. I
was injured after turning the saw off and before the blade coasted down to a
stop. In this instance the SawStop would have prevented my injury.
The point of what? Having a motion detector? If that is what you are
talking about, the motion detector to detect the spinning blade would enable
the system. If no "predetermined" minimum speed is detected by the motion
detector the system would be disabled. This would prevent the system from
tripping when changing blades or turning the blade by hand.
Now you would be creating a substantial
I suspect this is already built in for the purpose stated above and a motion
decector or speed sensor would be inexpensive. Almost every automobile has
a speed sensor at the crankshaft to determine timing. Same thing could be
used here. A magnet and a sensor.
Exactly but the more safety you have built in, the less likely you or I or
any one else will be injured. And don't even think that you are 100% not
lazy or stupid when operating any equipment 100% of the time. You are
probably human like every one else and are not capable of not making a
Your paying attention to what you were doing at the time probably would have
as well and I bet you never made that same mistake again. I don't know what
happened to you but if you were already in a position to stop the saw, it
seems likely that you could have avoided it.
That is far more difficult than you give it credit for. Where exactly do
you intend to mount this detector and what is going to power it after you
shut the power to the was off. At best, I would put a 5 to 10 second delay
in it's shutdown to give the blade time to stop which would serve your
purpose and cost much less.
Where exactly do you intend to mount either the magnet or the sensor? And
even then, they will still do nothing without the monitering and logic
circuits the use them.
I disagree with this. I have come to find that when something has too much
safety equipment on it, the users lose respect for it and simply begin to
use it more dangerously. I did notice that in a past thread someone sade
the claim that statistics show less injuries on a RAS than on table saws and
I would bet that that spinning blade above the table makes the user VERY
aware of what they are working with.
I never made that claim and have been injured, sometimes do to being stupid
but I seldom make the same mistake twice.
If at first you don't succeed, you're not cut out for skydiving
Actually I make the same miustke again about 9 months later and realized
that this is how I must have been injured. Fortunately or not, I did not
have as much thumb hanging down as it is half gone now and did not repeat
the trip to the ER. Believe me when you are injured like this you may or
may not remember what happened exactly. For days I thought it was kick back
only to realize no wood was damaged. This makes it hard to prevent a freak
Where exactly do you intend to mount this detector and what is going to
power it after you
The dectctor can be mounted to the trunion and monitor the arbor pully or
shaft. The crank shaft saensor on many car engines is simply a closely
mounted sensor, "about the size of a small cigarette lighter", counting the
times a magnetic spot on the harmonic balancer passed by it in a given
amount of time.
The saw always has power, just not always going to the motor. The sensor
could be energised from the live side of the on off switch.
From what I understand the SawStop has these capabilities and I was simply
explaining one of the possible way that this can be accomplished. I am not
saying that this is in fact how it was accomplished but simply how it could
Again, the magnet could be a 1/4" long pencil lead sized object imbedded in
a small drilled hole on the end of the arbor. The sensor coud be mounted
close to the end of the arbor. As far as the logic and circuits, that stuff
is cheap and mass produced. Many battery operated drills have this
circuitery to maintain speed when a load is applied to the drill.
No, but you get one helluva chance to make a great impression on a wheat field.
"Political language... is designed to make lies sound truthful and murder
respectable, and to give an appearance of solidity to pure wind." George Orwell
As I understand it from the material I posted here, if the blade is
moving the device is active. Once the blade stops, the device is off.
"Sometimes history doesn't repeat itself. It just yells
'can't you remember anything I've told you?' and lets
fly with a club.
-- John W. Cambell Jr.
The questions are (a) does it trip and cost you 50 bucks and a new blade if
you touch the blade while the blade is not turning and (b) does it fail to
trip and let you get cut if the power is turned off but the blade has not
While it is inconcievable to me that anyone would try to market such a thing
without making provisions for the two conditions mentioned above, I have
see manufactureres do enough really stupid things to agree that these are
I distinctly recall a post in which someone did describe what happens in
those situations based on his personal experience either with a delivered
saw or a prototype, but now I can't find the post. Something about there
being a green light that is on whenever it is armed, which included a
certain period of time after power-off, and when the light goes out then
you can touch the blade without triggering. Trouble is I may very well
have dreamed it.
Reply to jclarke at ae tee tee global dot net
From the response directly from SawStop,
A. Speculation here, (a) it will not trip when the blade is not turning.
It would be tough to change blades with out tripping it. (b) if it did trip
it is likely that neither the blade or cartridge would be damaged. IMHO
damage would be the result of stopping a blade spinning at 3600 rpm in 1/8
th of a revolution.
B. No Speculation, the device will trip or trigger if the blade is spinning
even after the saw was turned off.
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