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Table Saw Blades & The Laws of Physics

If you wanted to make a device to throw pieces of wood at a high rate of speed, how would you design it? You could look at the machines used in sports for throwing things and start with a spinning disc, say 10″ in diameter. If you had the disc sticking up from a solid table, and had another solid piece at a right angle to the table and parallel to the blade, all you would need to do would be to put a hunk of wood between the spinny thing and the solid parts. Sounds a lot like a table saw, doesn’t it? When we think of the risks of using a table saw, we think of the teeth, but the spinning parts of the blade that don’t do the cutting are where many table saw accidents begin. Many table saw accident stories begin with “the wood I was cutting suddenly went flying . . .”. This forum post from SawMill Creek is an example of that. The likelihood of this sort of thing happening is directly related to the size of the wood. If the length of the material is shorter that the exposed part of the blade, and the material is trapped between the blade and the fence the odds of the material kicking back are quite high. This is why you should never use both the miter gauge and the fence together. That is obvious if you’re cutting completely through the material. What’s not so obvious is that the same laws of physics are at work, even if you’re only making a partial cut, such as the shoulder of a tenon. I know that many of our readers have done this for many years without getting hurt, and will likely want to argue about this. It isn’t as dangerous as making a through cut, but that doesn’t mean it is entirely safe.

The temptation to use the fence as a crosscut stop is understandable. It’s there, it’s accurate and it doesn’t take much time to set it. If you’re not going all the way through the wood, you may get away with it, but it is still a risky operation. But you can reduce the risks to nearly zero if you take a few seconds to clamp a block of wood to the fence ahead of the blade. You still have all the benefits of the fence’s adjustability, and repeatability. The only downside is you have to hold the work firmly to the miter gauge. That really isn’t a negative, it’s what you need to do to stay in control of things.

As you can see in the photo above, as I make the shoulder cut for a tenon, the space between the end of the board and the fence prevents the wood from being trapped and propelled. My hand is a safe distance away, and it isn’t moving toward the blade. That takes care of the shoulder cuts, but how can I quickly remove the excess material to make a tenon? There are a bunch of ways to do it. I could switch to a dado blade, I could use a tenoning jig, or I could make the cut on the band saw. Let’s say I don’t have or don’t want to use any of those methods. I only have a couple tenons to make and I don’t have much time. How can I waste the rest of the tenon? The last thing I would do would be to shove the end of the board into the side of the blade. Here is a way that is faster and safer:

After the shoulder is cut, I can make a series of crosscuts, moving the work away from the blade after each pass. I don’t need a stop because I’m moving away from the shoulder. I don’t need a precise distance between the cuts. My hands are always in a safe position and moving in a safe direction. If something goes wrong or I get distracted my hand isn’t moving toward the saw blade. OK, but what about all that stuff between the saw kerfs; how do I remove that to get a nice smooth tenon?

Here are two simple devices that a lot of woodworkers apparently don’t know about, a chisel and a bench hook. After making the cuts at the table saw, I put the wood on the bench hook to hold the piece firmly with my hand in a safe location, and slice off all the waste with a chisel. It doesn’t matter how you feel about hand tools, this is quick, easy and nearly foolproof. It takes far less time than it would to nibble all this stuff away at the table saw, and the results are just as good if not better.

Speed doesn’t mean much if you have to head to the emergency room. With an understanding of how the tools work and the material behaves, there isn’t any reason that you can’t work efficiently and safely at the same time. If you have to ask “Is this safe?” you should stop, look at the process and don’t go any farther until you can say, “This is safe.”

— Robert W. Lang

Popular Woodworking Magazine is committed to working safely, and we have made available articles on table saw safety that every woodworker should read.

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Showing 21 comments
  • rsites

    Simple and safe, what a great article!

  • willcon

    Once again the most important tool comes out in the workshop…COMMON SENSE! If it “feels” dangerous, it is! This is not only safer, but smarter. There were so many things that felt wrong about that other demonstration. Thanks for showing a much better way.

    Safest way to tenon? Hand saw.

  • WilliamDavis

    I believe the danger of using the rip fence as a crosscut stop arises when you cut a piece completely off the end of a board. That is a suicidal practice because the cut-off piece can and will jam between the fence and the blade and much excitement results. The tenon cut doesn’t create a loose piece so I feel it is safe.
    I also like the fact that the piece can’t drift towards the blade and damage the shoulder cut.
    I use one hand to keep the piece tight to the cross-slide and move the piece back and forth over the blade with my other hand at the end of the piece AWAY from the blade. That hand is not moving towards the blade. If I slip it will come in contact with my other hand long before reaching the blade.
    If the piece is so short that my hands would be close to the blade, I’d revert to Bob’s stop block method.

  • Harlan Barnhart

    European table saws typically have a fence that can be advanced or retracted parallel with the line of cut. To make a cut like you demonstrated, just slide the fence back past the blade. It’s also safer in long rips.

  • leejones

    Thanks for the idea and picture of a bench hook. It’s so obvious now that I see it. I’ve been doing woodworking (part time) for 50 years — my father started me when I was very young — and I had never heard of a bench hook. I’ll build myself one tomorrow.

  • Nordichomey

    Great points Bob… especially the direction of hand movement AND I get to use my chisels!

  • BillT

    I use a combination of the “unsafe” method espoused by that other magazine, and this one.

    I first make a series of parallel cuts, exactly as Bob has shown here. I usually make them very close together, though, so that either there are not little bits left in between the kerfs, or any that are left are very, very thin. Then, to knock out any little bits left in between the saw kerfs and to flatten the side of the tenon, I do the “other” method and slide the tenon across the blade. That way, rather than using the “slide sideways across the blade” technique to hog off all of the waste, I am only trimming up the tiniest little bit and smoothing out the tenon cheek. It kind of skips across the blade with very little resistance, and leaves a quite flat and smooth tenon cheek.

    I then fine-tune with a shoulder plane as needed.

  • Recruiter

    The one that always gets me, almost every week, is when I watch “The Woodsmith Shop” on PBS. Almost every week they show using the miter gauge and fence together, whether it be with a regular blade or Dado blade. Every time they do that, I keep asking myself, why hasn’t someone told them, they should not be teaching this practice. IT’S DANGEROUS!!! Well, maybe someone from that magazine will be reading this blog.

  • David Keller

    Bob – it shouldn’t surprise you that the editor at “that other WWing magazine” is espousing unsafe practices. The man is well known to us former subscribers and users of the website as unimaginative and extremely arrogant. His input and creative decisions at that magazine is the principal reason why I and many others chose to cancel.

  • B Jackson

    I use similar nibble techniques on my bandsaw, but for cutting tenons, I’m likely to use a 3/4″ bit on the router table after making the shoulder cuts on the bandsaw. It may be better to devise a jig to carry the stock into the cut by no more than 1/8″ increments so that your hands are unlikely to slide into the cutter / blade. How I carry out this technique and what tools I use is likely to depend on the size of the tenons I cut. I certainly don’t envision nibbling away really wide tenons on the bandsaw. But it seems tenons no wider than 3″ would be OK. And then one question: what if you were fitting a tenoned stock to a curved mortised stock? How do you cut a curvilinear shoulder?

  • MarkS

    Thanks Bob. I was bothered by what FWW said but couldn’t put my finger on it. I’ll continue to follow the same practice that you highlighted.

  • Fred West

    Bob, a truly safer way than was shown in a video elsewhere that not only used the fence but cut sideways across the wood.

  • Eric R

    You have a lot more know-how then me Bob, so your method looks like the one I’ll use.

  • bbrown

    This would be a great first article in a series on safe methods of work.

  • bobbollin

    Thanks for the article and the lessons, Bob. I have been using the “block of wood” and multiple crosscut methods for a long time, but I’m glad you are getting them out there for all to view.

    To reiterate what the man in link says, if your tiny little mental voice is telling you, “This is stupid!”, THAT is the time to stop and re-think your methods. I have had 2 experiences with kickback, one of which could have been serious but wasn’t due to safety glasses, but in each case that little voice was whispering…and I didn’t listen.

    I listen…and listen hard…now.

    There’s ALWAYS a safer way!

  • J. Pierce

    I don’t have a tablesaw, so I can’t use one, but I appreciate any discussion that brings up how to work safely and the importance. I also like that in the pages of PW I haven’t seen any “questionable” practices offered or displayed like I have in some other publications.

  • Richard Dawson

    I am constantly amazed by people who, after suffering an injury, mention they “knew it was going to happen” about a tenth of a second before it did.

    We each have a little voice in our gut; we need to listen to it, else get the message about a tenth of a second too late.

    I concur, an excellent response to a dangerous practice.

  • Gary Roberts

    My hat’s off to you Bob! An excellent response to a dangerous practice.

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