V Impressive - Safe Fingers at last

[rwatson]

Wow - fantastic idea

ttp://www.sawstop.com/contractor/contractor_home.php

for a video of a power saw that self destructs rather than cut off one of your digits!

Who needs Jet Cars!

[PAR]

Yep, they work great and have been around for a while, though they self destruct when used and aren't cheap, they are less costly then finger replacements.

[marshmat]

A very clever device, indeed. It's a popular case study in mechatronics/robotics classes.

A few notes, though:
- As PAR points out, the brake block fuses to the blade when actuated, thus you must replace the blade, brake block and release mechanism when it trips.
- It applies a small electromagnetic field to the blade in order to sense your finger; thus, when cutting conductive materials (ie, aluminum) you have to bypass the stop mechanism so that it doesn't mistake your workpiece for a finger.

[PAR]

I've often wondered if drop of sweat that have landing on the work you're shoving through the saw will trip the device. I've leaned over saws while pouring out enough sweat to steam bend the stock once cut. Having an expensive finger saver trip off, without my body parts being in harms way would piss me off.

[rwatson]

As I understand it, the 'grounding' effect is what does it - a drop of sweat or even some condensation on the wood wouldnt have enough of a change in electrical potential.

I would bet that if that sausage in the video wasnt being held by a persons hand, the saw wouldnt have stopped. Worth confirming before paying the big bucks though.

[Fanie]

An encouragement to be wreckless maybe.

[PAR]

All my life I've had this terrible feeling that loosing a finger, hand, arm or other body part was just going to be my fate. I just use these tools too often and the odds suggest I'm long over due. I've seen too many incidents, picked up fellow worker's, still warm digits and placed them in a plastic sacks on their chest, for the ambulance ride to the hospital, with hopes they can sew them back on.

It's nice to see this level of safety is available, but I still want to see if it can be beaten or fooled, because it would be my luck, that I'd defeat the safety feature without realizing it.

[Fanie]

All my life I've had this terrible feeling that loosing a finger, hand, arm or other body part was just going to be my fate.
Same here. I have cosiously made a decision to work differently around my saws after almost amputating a finger in a band saw while cutting a piece of bone... and it wasn't my own :D

I always place my hands so that the workpiece cannot pull my hands or fingers towards the blade. I don't use any saw if I'm tired, cannot see properly, sweaty (slippery) and especially not when I'm in a hurry. I also make sure the workpiece is properly supported even if it means I have to make a jig.

It's either that or be prepared to spend much more time and discomfort and costs getting sowed back together again.

[alan white]

The Sawstop saw is best suited for schools, factories, and any place where a lot of people use the saw. Reason one, the saw is expensive. I can't remember how much but it seemed it was a few thousand.
If I ran a 10 man shop I might consider one.
However, take that same money (what is in excess of the cost of a good Unisaw) and invest it in an eye-wash system, safety training for employees, an explosion-proof cabinet for solvents, and on and on (even working shorter hours, or taking more breaks-- it's often fatigue that causes accidents, and you've probably done more to ensure full retirement digitation than the saw might provide for the same money.
I too have seen a few accidents, including my own, but mostly employees, and in each case I know they were doing something they shouldn't have been doing.
One accident, my left ring finger kicked back by a dull jointer-- it still looks and works like a finger, until you look close, was caused by my own stupidity. I was young and working in a custom furniture shop. The jointer was in need of resharpening, I informed the boss, and he told me it was okay. I knew it might kick, but went ahead and used it instead of staning up to the boss. After that incident, I never let anyone else decide how risky a tool was.
I see a lot of older guys doing things with saws I would never do. They obviously have never lost a finger or went to the emergency room. They most likely will be overtired one day and that will be all it takes.
Some people, whether carpenters or car drivers, will take unnecessary risks until they learn by first-hand why not to.

[Fanie]

until they learn by first-hand why not to
EXPERIENCE is something that makes you recognise a mistake when you do it the second time ;)

[alan white]

With all kinds of ways people might learn not to risk danger, some people only appear to learn by experience. A guy I know recently chewed a hand up on a shaper. Yechh! He was a "balls to the wall" type (long hours, thrasher), real ambitious and maybe a little reckless. That served him well until the accident. He might have finished his career unscathed, or he might have ended it years ago. As it is, he has one usable hand.

[Itchy&Scratchy]

Chopped a few fingers off in a spindle moulder a few years ago, all guards on and all safety precautions adhered to. I havent had a look at this item that you guys are speaking about but I have my doubts whether any machine can stop or self destruct without doing some damage before it stops-maybe its designed to limit the damage instead of chopping them off completely.

J

[alan white]

From what I understand, the machine is so fast in stopping the blade, it only scratches the fingers. Electricity reacts at the speed of light. Apparently, the solonoid or whatever is very fast.

[PAR]

No it actually stops fast enough Itchy, just costs a lot and is a one shot deal.

[offshoreonly]

There was a show on discovery channel a while back. I dont remember the name of it, but they do super slow motion video of all sorts of things. They did one on this saw. There was a rep/owner/someone from the manufacturer that actually used his own finger to prove the saw works. It only left him with a slight mark. No blood or anything. He did push his finger into it slowly though. I wonder if it was a kickback that yanked your hand/fingers into the blade rather quickly, if it would have the same results.

[marshmat]

PAR - yes, you can disable the blade-stop feature on the Sawstop. There's a manual override to use if you're cutting aluminum or other conductive material.

The saw can be returned to service after it trips; this involves replacing the blade, the brake block and the fusible link that holds the brake block in place. (And re-compressing the friggin' big spring that drives the block into the blade.) Not sure how much this costs, but probably a couple hundred bucks or so to put it back in service.

My main concern with it would be that the system does involve a DSP (digital signal processing) chip to decide when the electric charge on the blade has dropped quickly enough to trip the stop mechanism. I have a hard time trusting computerized stuff, and I would certainly not ease up on normal safety precautions as a result. (Indeed, I would probably not even tell anyone using the saw that it had the self-stop feature.)

[alan white]

Wow. What some people will do to make a sale! Things do malfunction once in a while. I wouldn't hjave done it for love or money!