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During this evaluation I did two brake deployment tests and got them both on video. That's good because you wouldn't believe me without being able to see it yourself!
Click image to enlarge

SawStop Professional Cabinet Saw - Part 2

Bang! You’re not dead!

Text, photos and video by Tom Hintz

Posted – 3-22-2012


As soon as I got my SawStop Professional Cabinet Saw I knew that my viewers (and me) would not be satisfied until I triggered the SawStop System at least once. Yes, here we go again……but safer this time.

I should point out that nobody, including the folks at SawStop is saying that the SawStop System protects you from everything you can do wrong at the table saw. Nothing can. Nobody can predict all of the ways people will get themselves in trouble or know when that moment of brain fade will occur that puts a hand in the wrong place. Plus, wood itself is inconsistent, adding another variable that can help things to go wrong unexpectedly. The SawStop System will certainly do its job at reducing injuries as much as is possible. But as always, you must remain in charge of your wellbeing and use the SawStop System as another tool in your safety effort.

The Misconceptions

You can use the Bypass Mode to see if cutting wet wood (left) would have triggered the brake. In the video I cut through this nail (right) to show that unless you are touching the nail itself when the blade strikes it, the SawStop System will not detect it and will not deploy the brake pawl.
Click images to enlarge

Some believe that simply cutting wet wood will trigger the SawStop System but that is not necessarily so. If there is enough water in the wood to create an electrical path from your hand to the blade it is could trigger the brake but is probably too wet to be cut safely anyway.

Another factor to consider is if the wood is pressure treated with the newer materials that often contain large amounts of copper. Combining elevated moisture levels with the copper in some preservatives could create a situation where the SawStop System might trigger the brake.

Cutting through a piece of metal such as a nail or screw does not itself trigger the brake. If your finger is touching one end of the metal when the blade hit it the SawStop System could trigger. But, we are supposed to be looking for metal in the wood before cutting it anyway. SawStop puts a layer of nonconductive plastic on the face of the aluminum brake shoe to try and keep metal chips from creating a momentary connection between the blade and shoe which could also trigger the brake.

Bypass Mode

The SawStop System has a Bypass Mode that can only be engaged using the included keys. This mode turns off the trigger system that deploys the blade brake pawl but retains the detection function. This Bypass Mode lets us make careful test cuts in suspect wood to see if it would have triggered the brake. We have to remember that the inconsistency of wood makes this test advisory which means we still have to use our heads. If the wood feels too wet, wait for it to dry or get dry wood.

To enter the Bypass Mode you have to insert the key, turn on the power and wait for the initializing to finish then turn the key and hold it. After a second the green light will blink slowly and the red light will blink once. Continue holding the key at the end of its travel pull the red paddle out to start the saw motor. Continue holding the key for at least one more second until the motor starts and the red LED flash once more and the green light will begin flashing indicating that the system is in Bypass Mode. You can release the key and make the test cut.

The SawStop System cannot enter Bypass Mode without the key being inserted in the switch box and turned at the right time. Bypass Mode was designed for testing, not every day operation.
Click image to enlarge

When you finish the test and shut the motor off the Bypass Mode remains engaged until the blade actually stops. Then when you start the motor again, the SawStop System automatically reverts to its full protective function and will trigger the brake if it detects contact. You must go through the key sequence to enter the Bypass Mode again.

The procedure for entering the Bypass mode is designed to make it very hard to accidentally put the saw in this mode and unintentionally disabling the blade brake. The keys should be removed and kept in a safe place when the Bypass Mode is not needed as the SawStop System cannot get into Bypass Mode without them.

In the accompanying video I use the Bypass Mode to make test cuts in wet wood and wood with a nail in it. In each case I made one cut in the Bypass Mode and when the system did not detect contact I restarted the saw in the normal brake enabled mode and made another cut. In both cases I was able to make cuts without triggering the brake as indicated by the lack of detection in Bypass Mode.

I then started cutting into a piece of sausage that I was holding on to with the saw in the Bypass Mode and it showed that it detected the contact and would have triggered the brake. Then I turned the Bypass Mode off and made another cut, this time with the SawStop System fully operational and it deployed the brake as you can see in the video.

I show you in the video something that flat amazed me after this first brake activation. I could not find any indication of the blade cutting into the sausage though we can see the sausage react to being touched by the blade in the video. In this case the SawStop System reacted BEFORE injury occurred. It could be that the casing of the sausage is tougher than human skin so there may have been a slight injury to a bare finger but I have a hard time believing it would be more than a scratch. It is important to know that lots of people actually saw off multiple fingers by simply pushing them into the blade like when ripping a board. You don’t need a bunch of speed or force to do a bunch of damage to yourself on a machine designed to slice through heavy oak and hickory. You are way softer.

You can see how deeply the blades teeth sunk into the brake pawl (left) before crushing some of the pawl structure in a planned deformation event. The pawl and teeth (right) here are from the second test and while the teeth do not appear damaged just by looking at them the tremendous hit they took demands that the blade be junked out or inspected by the manufacturer! There is no way I use a blade that has been through something as dramatic as a SawStop deployment. See the video below for visual proof of the impact!
Click images to enlarge

As you can see in the video and photos the damage to the brake pawl is significant, including collapsing the rear most cavity near the pivot which is also distorted. The blade sunk into the aluminum pawl more than tooth-deep at the leading edge showing that the folks at SawStop did their homework in designing this system.

After a Trigger Event

If the SawStop System triggers the brake the cartridge and blade are often fused and must be removed as a unit. The instruction manual goes over this procedure well but I can tell you that experience in doing it helps. Using the blade wrenches as shown in the instructions it takes a couple minutes but before long you have the damaged pieces out.

After the trigger event the blade arbor will be in its down position and must be returned to its normal position for operation. A gloved hand is all you need to swing it back up until it contacts its stop. There is a detent that holds the blade in this position until sufficient force is applied by the braking event to force the blade down below the table.

Installing the new cartridge is also explained well in the manual. If the cartridge is not properly installed the saw will not operate. An important part of this procedure is checking the gap between the cartridge pawl and the blade. The included wrench and gauge make this an easy task as well.

Before going through this post-brake activation procedure myself I thought it would be more involved than it is. This is another testament to the thoughtful design of the SawStop System. I did find that it is easy to get the cartridge ahead of the blade, cocking the blade on the arbor which makes it more difficult to extract. The manual and the folks at SawStop had told me about this but I managed to mess it up anyway. The good news is that this mistake does not damage anything but your ego and the length of time required to get the now joined blade/cartridge unit out.

The severed piece at the top (left) came when I swung the sausage down onto the blade with the SawStop System in Bypass Mode. It detected the sausage but did not deploy the brake. The small cut (right) is what happened when I turned off the Bypass Mode and again swung the sausage down on the blade. You can see the relatively small cut and destroyed brake pawl that cold very well save you some fingers. Incidentally, the spot of blood on the brake pawl came from me not wearing a glove when I started removing the blade and cartridge. the human mind is capable of dumb mistakes just about anytime!
Click images to enlarge

Installing the new cartridge and blade was easy and I had that done in a couple minutes. I carefully used the included gauge to set the blade to brake pawl clearance and I was ready to trash my second cartridge and blade!

Test #2

This time I was going to swing the sausage down onto the blade at roughly the same angle as my hand was moving in the slow motion video of the Kickback on Camera footage. I say roughly because I can only approximate the angle and speed. The important thing here is to be consistent in the swing between the Bypass Mode test and the full activation one. It is unlikely that any two kickback events are identical but I think we can achieve a reasonable representation of the difference in injury between contact with an unprotected blade and one with the SawStop System in force.

First I set the SawStop System in Bypass Mode and then carefully swung the sausage down onto the blade, angled towards the operator side of the saw to match the path my hand was taking when it passed over and alongside the blade in the kickback video.
I expected lots of damage to the sausage with direct blade contact augmented with a little speed and force behind it. That proved to be true when the sausage was torn in two leaving rather ragged edges. I checked the lights and the SawStop System had indeed detected the contact. I started thinking that this doesn’t bode well for the SawStop System because as easily as the sausage was severed I didn’t think the system could catch it in time.

I armed the SawStop System fully and again swung the sausage down onto the blade in the same direction and as close to the same speed as I could. When the sausage contacted the blade there was a bang and the blade was gone below the table. I was shocked to see an approximately 1” long by about 3/16” deep cut in the sausage but no other damage. So much for the speed and force theory of compromising the SawStop System. The cartridge and blade were trashed naturally but if this had been my hand, I’d be only slightly injured.

Conclusions

Video Tour

The SawStop System is remarkable in the speed at which it stops and withdraws the blade. I honestly did not expect it to work very well in my second test because of the speed and force behind the sausage. I have never seen the SawStop System tested like that. But, it happened right there in front of me. The hot dog thing is cool and has sold lots of people on the SawStop System but I think this higher speed/impact test shows me that this system can mitigate the severity of what would otherwise be far more serious injuries.

We have to remember that the SawStop System will not prevent all injuries and in my test the hand being cut may well have needed a few stitches but without the SawStop System it is not hard to see an amputation level injury to one or more fingers. There is no other conclusion than that the SawStop System works.

It is also obvious that people are not aware of the quality of the table saw surrounding the SawStop System. I have had lots of email and seen lots of posts regarding the SawStop System and not one mentioned the high end table saw supporting the SawStop System itself.

If you are looking to step up your table saw you owe it to yourself to check out the SawStop Professional Cabinet Saw, no matter how careful you think that you are being. Being human brings with it liabilities, one of which is making mistakes now and then. Most major woodworking injuries result from innocent mistakes made by people who know better. Having the SawStop System lurking within the table saw could very easily mean you wind up with a little cut rather than something much, much worse.

See Part 1 of the SawStop Professional Cabinet Saw Review - Click Here

Visit the SawStop web site – Click Here

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