Sawstop Rave: not what you think

[Brad Gobble]

[note: this is not a "should you buy or not" thread so if you think they are worthless please save your breath... there are 100 other threads debating the necessity of the SS's break feature]

I have a 4 year old SawStop ICS. Love it. Picked it up used for a great price (see FWW forums for gloat - username BradG). It does it's job well every single time I fire it up.

I was cutting some 50 yo maple recovered from a bowling alley into useful pieces for a current project. half way throug a simple miter of a 2x3 the blade spins down as if I'd turned the saw off. I backed the piece of wood off and saw that I had missed a metal scrap (tip of a nail) with the metal detector. I was pleased but also concerned: I thought the brake would have triggered, costing me a very nice Matsush!ta blade and a break cartridge, nearly a $175 total bill. However, what about my fingers in the future? I've been cut once before and the stitches were 10x worse than the blade.

I called Sawstop - their reply is that the trigger mechanism is capable of distuinguisning between metal and meat (square / stepped curve vs. smooth curve) and behaved as designed. Wow this thing is smart!!

I still put new batteries in my metal detector and am that much more careful, but I thought I'd share yet another smart feature of a well reviewed and well used tool.

[Brian Penning]

[note: this is not a "should you buy or not" thread so if you think they are worthless please save your breath... there are 100 other threads debating the necessity of the SS's break feature]

I have a 4 year old SawStop ICS. Love it. Picked it up used for a great price (see FWW forums for gloat - username BradG). It does it's job well every single time I fire it up.

I was cutting some 50 yo maple recovered from a bowling alley into useful pieces for a current project. half way throug a simple miter of a 2x3 the blade spins down as if I'd turned the saw off. I backed the piece of wood off and saw that I had missed a metal scrap (tip of a nail) with the metal detector. I was pleased but also concerned: I thought the brake would have triggered, costing me a very nice Matsush!ta blade and a break cartridge, nearly a $175 total bill. However, what about my fingers in the future? I've been cut once before and the stitches were 10x worse than the blade.

I called Sawstop - their reply is that the trigger mechanism is capable of distuinguisning between metal and meat (square / stepped curve vs. smooth curve) and behaved as designed. Wow this thing is smart!!

I still put new batteries in my metal detector and am that much more careful, but I thought I'd share yet another smart feature of a well reviewed and well used tool.


Hmmmm...wonder why my SawStop didn't do that when the blade hit my miter gauge once.

[Peter Aeschliman]

I'm no engineer. But my understanding is that the conductive material needs to have enough mass to cause a significant voltage drop in the blade. A small nail embedded in non-conductive wood won't necessarily cause the voltage drop necessary to trigger the brake.

The human body is big enough to cause that voltage drop.

Apparently, if you throw a hot dog at the spinning blade, the brake won't trigger. If you hold that hotdog and touch it to the blade, it will... because it conducts the current through the hot dog to your body.

[John Coloccia]

I'm no engineer. But my understanding is that the conductive material needs to have enough mass to cause a significant voltage drop in the blade. A small nail embedded in non-conductive wood won't necessarily cause the voltage drop necessary to trigger the brake.

The human body is big enough to cause that voltage drop.

Apparently, if you throw a hot dog at the spinning blade, the brake won't trigger. If you hold that hotdog and touch it to the blade, it will... because it conducts the current through the hot dog to your body.

What about if you throw a fried chicken leg at it? :p

I've been using mine about a year now, and to be honest I've completely forgotten about the brake. I only think about it when I read a thread about it. It's nice to know it may not fire if I run into a staple, or something like that. On a separate note, will you lumber mill guys please stop stapling little notes to the wood? I go a year without one staple, and then all of a sudden I find 2 or 3 in a batch. Errrrg.

[Steve Peterson]

Hmmmm...wonder why my SawStop didn't do that when the blade hit my miter gauge once.

The miter gauge is grounded and will allow a lot of current through the detector. The nail head is floating and will only allow a small amount of current to flow.

It is cool that SS can detect the difference between a small amount of metal and a finger. Then they shut down to try to minimize damage to the blade.

Steve

[JohnT Fitzgerald]

I believe that SS takes back triggered cartridges so they can read back the data stored inside and make it even better over time.

[Peter Aeschliman]

An interesting thing happened to me with a false brake firing the other day... still need to send the brake into Sawstop for analysis.

I had a piece of plywood sitting on the saw table without the saw running. I put it up against the rip fence and put the leading edge really close to the blade so that the workpiece wouldn't fall off the table.

I then turned around and walked over to my dust collector to get it started. Like a total bonehead, I forgot to pull the piece of plywood back before starting the saw. Turns out the leading edge was so close to the blade that it in a gullet between two teeth.

When I started the saw, it stalled. I cursed. I turned the saw off. No brake firing. But the saw wouldn't start back up right away. I cursed some more.

I waited a minute or so, and tried to start the saw again. It ran. I wiped my brow and let a sigh of relief. Turned the saw off, went and grabbed the piece I was trying to cut before, and tried to start the saw. Before the blade even started moving, I heard a pop sound. Many more curses ensued.

The brake had fired. The blade wasn't embedded in the brake. Again, if the blade moved before the brake fired, I couldn't see it with the naked eye.

All I can think of is that stalling the motor caused an overload which fried something in the brake cartridge, which maybe closed a circuit, which maybe caused the saw to think it had hit something conductive.

Who knows.

It was a huge PITA trying to pry the brake cartridge out.. the spring was still under pressure against the blade, because it hadn't compressed at all (again, the blade wasn't spinning). I did it really carefully and luckily it didn't cause any damage from what I can tell... no significant arbor runout, and a new cartridge and blade put the saw back in service.

[Neil Brooks]

On a separate note, will you lumber mill guys please stop stapling little notes to the wood? I go a year without one staple, and then all of a sudden I find 2 or 3 in a batch. Errrrg.


All the notes that I've come across have said one thing -- the same thing:

"Hi, John !"

:D

[John Coloccia]

Nice :rolleyes:

:D

[Kyle Iwamoto]

The ICS SS has a current sensing circuit. This is to detect against bogging down that 5 hp motor, pinching and then tossing the lumber back at you with 5 horses of 220V power behind it. My saw stopped too, so I dug around in the manual..... Perhaps the nail had created enough additional resistance to trigger that circuit.

[michael case]

Peter:
This is a guess. I think that when the blade started in the ply it distorted the blade and forced a portion of it too close to the brake. Contact with, or being close enough to arc with the brake will fire it. Just a guess, but it seems a likely cause.

Brad:
I hit a screw once with on my ICS and it didn't fire. I too called Sawstop and received the same explanation they gave you. I've come across a number of posts on this issue. They are really polite at Sawstop, but I bet they are rolling their eyes when guys like us call with this particular question. They must answer it about 5 times a day.

[Joe Mioux]

Hmmmm...wonder why my SawStop didn't do that when the blade hit my miter gauge once.

ditto that

[Prashun Patel]

I had an incident with my SS last week:

I was (stupidly) cutting a green cherry log to make into a turning blank. It got half way through, then the motor spun down. The light pattern legend in the manual said the saw detected a wet condition and was close to firing. I got the impression it was like a warning: this time I caught it, but beware next time. Pretty smart!

[Ted Wong]

They must have fixed something in the last couple of years then. Last time (about 2 years ago) our Sawstop hit metal it popped. I'm happy they were able to figure out a fix for that situation. I think metal contact has been the #1 cause of triggers in our shop.