Thread: This is for metal workers too!

Originally Posted by danielhobby

i will simply say that there are quite a few very carefull operators out there that have lost a digit or two and up until that micro second of red mist they belonged to the" it wont happen to me" group.If you dont touch the blade the unit wont need replaceing(a little like seat belts or airbagsheh!?

A friend of our family worked for nearly 40 years in cabinet making with no workplace injuries other than a few splinters. He was also known by his apprentices as a bit of a safety nazi. A few days before he retired he was cutting up some small pieces with a small table saw . When he finished cutting he switched off the saw and went to flick a couple of small bits of wood off the table and ended up taking two fingers off. It's that quick. It ruined the first few months of his retirement as he and his wife had extensive travel plans leaving Australia the day after he retired.

Hi Bob,
I wonder what saw stop would have done in that instance? Anyone know?

Stuart

p.s. I had an uncle that worked for himself for over 20 years with out a scratch. Within a couple of year(?) he'd lost the best parts of three fingers and a thumb in two accidents on a spindle molder(isnt that what table routers are called?)

p.p.s. I guess I should add his made wooden furiture

The spindle moulder is the scariest machine ever made. I reckon mine is out to get me.

Originally Posted by Stustoys

Hi Bob,
I wonder what saw stop would have done in that instance? Anyone know?

Did you see my calculation results above - cut depth is related to speed. A simple flick wouldn't be more than about 1 m's so he would have received a ~1 mm skin puncture. The sawstop reaction time is so quick the digit has to be traveling at karate punch speed to remove a digit.

Hi Bob,
Sorry, what I meant was, would sawstop still trigger once the spindle is turned off? If so for how long? I've never seen anything about it monitoring the spindle speed. If it triggers when the spindle is off do you have to remember to put it on bypass every time when you are setting up?

Stuart

Originally Posted by Stustoys

Hi Bob,
Sorry, what I meant was, would sawstop still trigger once the spindle is turned off? If so for how long? I've never seen anything about it monitoring the spindle speed. If it triggers when the spindle is off do you have to remember to put it on bypass every time when you are setting up?

Stuart

Good point!!!

I had a look around their website and couldn't find anything but what I did find was that the reaction time for Sawstop is now showing as 3 - 5 ms. This is not so good as the 1 ms I based my initial calcs on. It means a push and slip injury goes from a skin nick to the likelihood of a bone cut. Based on this it probably probably still not take a finger off but it's not as good as I first calculated.

Another thing I turned up was on the Wikipedia entry for Sawstop where they claim the blade stops in 1/8" of rotation.
My calc for this is as follows
3000 rpm = 50 rps
0.005 s x 50 = 0.25 rev
For a 12" blade 0.25 rev = 9" or rotation.
To get the claimed 1/8" rotation the reaction time needs to be 0.17 ms (can someone check this?)
However there is another factor and that is that the blade is pulled town and back at the same time it is being slowed down. This is probably more important than the rotational speed being slowed.
To do a more complete analysis would required a time stamped slomo video of the triggering event.
I've wasted more than enough time on this.

I also found a page with pictures of finger injuries
SawStop - The World's Leading Maker of Safe 10-inch Table Saws » Finger Saves
Of course they are not going to show anything too bad.

Stu, I could be wrong here but I'm pretty sure I read or maybe heard at one of the demos at the Wood Show that the Brake sensing unit stays active till the blade has stopped moving

Originally Posted by Stustoys

How many airbags do you know with a bypass button?

at least 2 in my cruiser...a little switch that you can turn off the side airbags for driving on inclines....
factory fitted!!!

Originally Posted by BobL

Another thing I turned up was on the Wikipedia entry for Sawstop where they claim the blade stops in 1/8" of rotation.
My calc for this is as follows
3000 rpm = 50 rps

I got as far as here and you lost me.

I assume the " in 1/8" is a typo?(or its possible I am misunderstanding completely)

50 x 0.125=400 So that 400 1/8th of a turn per second
1/400=0.0025. thats not a lot of time even if they mean from when the brake hits the blade(opposed to when it is triggered, which would be a little naughty)

Hi DJ,
Now you have me wondering how slow a speed it turns off.

Stuart

Originally Posted by eskimo

at least 2 in my cruiser...a little switch that you can turn off the side airbags for driving on inclines....

What!!!!!! just so long as you remember to turn them on quickly if you roll it?
Now thats a new one.

Stuart

What concerns me about air bags was when I had my 2008 Hiace had a head on with a Honda Civic and totalled both cars neither car's air bag deployed. I thought that was what they were supposed to be for? I can understand maybe why mine didn't come on as I was probably only doing 10 kph but the other guy was doing about 50.

Bob I have to agree with you, I had a Holden combo which I got rear ended in by a p plater in a vectra. We where in an 80 zone and I was stopped at lights she hit me that hard I was pushed about 20 feet and sandwiched between her and the car in front of me(not a good feeling when you have the brake pedal to the floor and you just won't stop).the seatbelt thingies went off , the entire contents of the van slammed against the cargo barrier and even the pen in my top pocket went flying. No airbags went off on either car though. They even have warning stickers on the underside of the sun visers about driving up gutters may set them off.....I hardly think so.

Originally Posted by Stustoys

What!!!!!! just so long as you remember to turn them on quickly if you roll it?
Now thats a new one.

Stuart

no dont have to do that..it...they come back on automatically when you get over 40kph ( i think it is)...

the car has sensors to deploy the bags if the car gets over a certain angle...hence the switch to prevent deployment as it is expected that one will put a 4WD in such situations on accasions.