SawStop and Swiss on rye
It’s Safety Week again. Among woodworkers, there’s probably no more volatile subject when it comes to safety than SawStop. And there’s probably no one more unqualified to talk about table saws than myself, since I have very little experience using one, and I don’t even have a table saw in my shop.
On the other hand, I do know a lot about safety procedures. In my day job, I’m a pediatric oncologist, and one of my responsibilities is to give chemotherapy to kids safely. As you might guess, this is a process where the results could be disastrous if a mistake occurs. It’s in this context that there is a lot of misinformation about SawStop technology.
Now, in this discussion I do not want to talk about nor do I care about the politics of SawStop. Here I am only addressing one thing: does SawStop make using a table saw safer?
A common comment that is made about SawStop is that having a safety device that prevents major damage from contacting the blade with a part of your body will make the user less vigilant, leading to more injuries, and that nothing can take the place of paying attention to what you are doing, which is enough for safe practice. This is a nice philosophy, with only one problem. No one who actually works with safety protocols believes this to be true.
The reason for this is the Swiss Cheese model, first developed by James T. Reason, a British psychologist, in 1990. This model is used to analyze procedures to see if they are safe, where they can be improved, and in the case of accidents, how they might have occurred despite existing safeguards.
In this model, slices of Swiss cheese are our defenses against an accident occurring. The holes in the cheese represent ways that an accident might get past each slice. For a woodworker in his shop making a cut on a table saw, one slice of cheese might represent his concentration as to what’s going on, another represents shop conditions, a third represents how well behaved the board is, the fourth is SawStop technology, and so on. If there are enough slices of cheese, and if the holes in the cheese are small enough, then the arrow might get through some layers, but will be blocked from passing through by another layer.
An accident happens when the holes happen to line up. Here the model turns a little surreal, because the holes are not fixed in position. Rather, they change size and move around over time. For example, over time the lighting in the shop gets worse as your fluorescent bulbs get older, or it gets messier as you get into your project. So the holes in that slice of cheese get a little bigger over time. You may decide it’s not worth putting the riving knife back for just one cut, so the holes in that slice get bigger as well. If you have a beer in your shop and then get back to work, more holes get bigger. Or maybe you decide to do one last thing late at night, when you’re tired. Bigger holes.
There’s no doubt that SawStop’s particular slice must have a very small hole in it. The data is not completely clear, but Highland Woodworking issued a press release in 2009 that over 600 cases of fingers were saved thanks to SawStop. There has never been a contact where SawStop failed to mitigate the damage that could have been done. And the fact remains that whatever the size of the hole in the SawStop slice of Swiss cheese, that hole is quite independent of the state of mind of the woodworker.
At work, we work very hard to try to eliminate the chance of a chemotherapy error happening to a kid by putting multiple layers of checks in the process. I have to write for the chemotherapy. The pharmacy double checks my dosing, my math, and the treatment plan for the kid. The nurses administering the chemotherapy also double-check these factors, and two nurses have to agree things are right before giving the chemo to the kid. The idea that we should prevent chemotherapy errors from happening by solely relying on the vigilance of the doctor is ludicrous. And I can promise that none of us in this process take our roles any less seriously because we know that other people are checking the chemo as well.
We’re not the only ones who use this model of safety. Airline pilots, firefighters, and nuclear power plants all use this approach. And there’s no reason why it can’t be applied to our shops as well.
This is why arguments like, “We don’t need SawStop technology because woodworkers being a little more prudent will fill the same role” simply are not credible. Prudence doesn’t fill the same role as flesh sensing technology. Neither do riving knives, better designed guards, or other alternatives that have been proposed. Flesh sensing technology has one job to do: prevent severe injury if a part of your body touches the blade. This is completely separate from the awareness of the woodworker. At that point, you’ve already gotten past all the other layers of cheese, including the personal awareness slice, so it will be a very good thing if it’s there. To say that you don’t need flesh sensing technology to be safe, now that the technology exists, is to say that we can remove a slice of Swiss cheese and be as safe as we were before. Again, that argument doesn’t hold water.
SawStop technology is sometimes criticized that it won’t prevent kickback. But it still is an additional layer for injuries due to blade contact. And it’s worth noting that SawStop table saws have always had riving knives, not splitters, as part of their standard equipment since 2004 — several years before the other manufacturers came on board.
Now, there are many reasons why a woodworker might not want to buy a SawStop table saw. If you don’t want to buy a SawStop because you don’t like the politics surrounding SawStop, that’s fine. And if you don’t have safety features high on your priority list for deciding on a tool purchase, that’s fine as well. But deciding not to purchase a SawStop because somehow it’s not really safer makes no sense at all.
Sentayehu Teshale is a woodworker in Addis Ababa:
As long as my chairs last, my customers will remember me.
Not once does he mention the obvious aspect of his woodworking.
(Via Robin Wood.)
Making Kumiko
The first in a series of really nice write-ups on making kumiko by Geremy Coy, a furniture maker in Washington, D.C. It looks like he’s using western tools, which makes me feel less bad about using Japanese tools to make western woodworking projects.
John Reed Fox: The Uncompromising Craftsman - Fine Woodworking
John Reed Fox:
If you want to have the hand skills that it takes to do this, you have to do it a lot. There’s just no other way. You have to spend a lot of time at it. The way to learn how to cut dovetails is to cut dovetails. The way you learn how to sharpen is to sharpen.
Rather than being intimidated by this, I think there’s comfort in the fact that practice is all it takes.
It is completely worth the six minutes it takes to watch the accompanying video, and listen to John Reed Fox talk about his work. I would love to meet him someday. My one link with John Reed Fox is that he made the body of the plane I used to illustrate the set up of a Japanese plane.
Resawing technique by Tanaka Kiyoto, a Japanese luthier. I love how he uses an assistant to stabilize his otherwise craptastic workbench. I’ll have to add that to my list of ways to make do when you don’t have a massive workbench to use.
There are more photos of his saw on his blog (Google translation). It’s interesting how his saw has deep notches in it much like western saws with a Tuttle tooth pattern.
(Thanks to Jameel Abraham for the link. Photo from Traditional Woodworker.)
UPDATE: apparently Tanaka Kiyoto’s assistant is his wife, according to the Google translation of this blog post.
Toshio Odate in his workshop. The Workbench Book
One of the more common knocks against Japanese woodworking techniques are comments to the effect of “Why would anyone want to work on the floor?” The thing is, with these techniques, you aren’t working on the floor. You’re sitting on your workbench.
Also, check out that awesome saw collection.
Source: brushfactorywoodwork
New DVD from Jay van Arsdale: "Japanese Hand Tools & Joinery"
Available for pre-order. I pre-ordered my copy.
No affiliation, etc.
User made maebiki saws from France, part deux
Bensonlook Son was kind enough to send me a followup on making a maebiki. For this saw, he used a 2.5 mm thick by 10 inch wide plate. The teeth were cut at 2 points per 2 cm (about 1½ ppi). He was able to grind a taper in the blade so that it was narrower at the top compared to the toothline. This must have been a labor of love since it took over 10 hours to complete, and required a great deal of care in removing the same amount of metal from either side of the plate, and to avoid twisting and ruining the temper of the steel from the heat of grinding.
Bensonlook mentioned that the steel still needs hardening, but doesn’t have an easy way of doing this. Although he said this about his saw:
I hope it will be hard enough. I tried the saw on (very dried) oak , it seem to work correctly.
Sounds like the steel’s hard enough to me.
My hat’s off to Bensonlook. He did a great job.
