Chris Schwarz's Blog

Tapered Sawblades: That's Not a Defect, it's a Feature

In the world of handsaws, certain topics are taboo (or should be).

We dare not talk about the origin of “the nib,” lest the conversation turn to the ridiculous.

When discussing backsaws, it’s best not to say if you think the back should be folded over the blade (you old-school traditionalist, how do you post on the Internet with that goose quill?) or if it should be a solid billet of brass that has been slotted (I bet you’d use a saw with a plastic handle).

And wading into the debate on Japanese saws vs. Western saws is, in the words of Vizzini, a blunder equal to a land war in Asia.

But today I’d like to talk a little bit about one verboten topic: blade tapering. Now, a saw blade can be tapered in a couple of its dimensions. With a handsaw , a 26″-long saw with no back , it was typical for the sawplate to be tapered in its thickness. The sawplate would be thickest at its toothline then get thinner up near the top of the blade. My beloved Disston D8, for example, is .039″ thick at the toothline and .029″ up at the top of the blade.

This kind of taper is quite useful. It means the saw is less likely to jam in a deep kerf. And I don’t have to add as much set to the saw’s teeth, so it’s easier for the saw to follow a line (more set creates a bigger kerf that the saw is likely to wobble in).

But that kind of tapering isn’t controversial. Though early handsaws weren’t taper-ground, most people agree that it was a useful invention and embrace it.

The other kind of tapering , the kind that makes tool collectors blue in the face , is in the width of a backsaw’s blade. With this kind of tapering, the sawplate is narrow up at the toe and wider back at the heel.

I’ve seen a lot of vintage saws, and I’m always surprised at how many are tapered this way. One school of thought is that this taper is a defect. Either the sawplate has come loose from its back and slipped down at the heel, or the saw was sharpened over the years to this shape unintentionally. So some tool collectors disassemble the saws, and pound the sawplate back into the back at the heel to remove this taper.

Unless the sawplate is flopping around, I think this is usually a mistake. After years of using a wide variety of Western backsaws, I’ve concluded that the taper is brilliant. Here’s why: It keeps me from sawing too far and crossing my baseline by accident.

Think about it. Let’s say you are cutting dovetails at your bench. The work is secured in your face vise and you are sawing a tail or a pin down to your baseline. Now, unless you are some sort of magic flounder, it’s impossible for you to look at the front and rear of your joint at the same time. And so when you get close to sawing to your baseline, you’ll peer over the board to see if you’ve hit the baseline on the exit side.

A tapered blade makes this process easier. When I saw dovetails, I simply saw until my teeth touch my baseline on the front face of the board. If the blade is tapered and I haven’t tipped my saw in a radical manner, then I haven’t crossed the baseline on the back of the board. Usually all I have to do is peer over the board, tip the tote of the saw up a degree or so and make one more stroke to hit my baseline on the back.

Here’s the backside of my dovetailed board , after I’ve touched the baseline on the front side.

The taper works like this for all your joinery , tenons, half-laps, you name it.

Now the naysayers claim that the taper might be useful, but it isn’t correct for a pristine, true vintage saw. It’s a user-modification, like the dual Weber carbs I’m contemplating for my Volkswagen. To that I say: Read Joseph Smith’s “Explanation or Key to the Various Manufactories of Sheffield” (1816).

The four backsaws shown in “Smith’s Key.” Note the tapered blades.

In case your copy of “Smith’s Key” ain’t handy, here’s the deal. This book was kind of like a clip art file for early Sheffield toolmakers. Engraving was expensive, so a toolmaker needed an image of a bevel-edge chisel for a catalog, they could get one from “Smith’s Key.”

“Smith’s Key” has one page devoted to handsaws and backsaws. And on that page, all four backsaws are shown with a prominent taper. If a tapered blade was a defect, why would you show that characteristic on a new saw in a catalog that might be used by as many as 150 tool makers?

By the way, I own two dovetail saws by modern makers that are tapered in width. My Gramercy Tools saw is 1-1/4″ wide at the toe and 1-3/8″ at the heel. My Wenzloff & Sons Kenyon-style dovetail saw is 1-5/8″ at the toe and 1-3/4″ at the heel.

– Christopher Schwarz

12 thoughts on “Tapered Sawblades: That's Not a Defect, it's a Feature

  1. Ray Gardiner

    Having dissassembled and tuned up a number of British made
    back saws, all the ones I have seen the taper is set by the
    assembly process, that is the blade is inserted into the back at an angle, the actual blade is rectangular. And no it hasn’t slipped or moved over time. The positioning of the holes in the handle and blade confirm that this was done deliberately.

    I agree with the sawing to a line theory, that explains why Dozuki’s have similar taper (albeit backwards !) However I would add that tapering the blade also changes the cutting angle of the teeth relative to the grain, which provides a more oblique cutting action. Look at the line of the teeth relative to the grain, rather that the line of the back.

    Nice blog Chris, informative as always.

  2. Adam Cherubini

    You’re a rabble rouser, Schwarz.

    This may sound far fetched, but I think all saws are tapered for the same reason; it moves the center of gravity of the saw and effects its moment of inertia. The result dramatically effects the way the saw feels. The tapered bladed back saw really does feel lighter in the toe and a little more nimble than one that is not tapered.

    Likewise, Mike Wenzloff’s kenyon long saws are a little fatter in the toe than comparably set up Disstons. This permits more aggressive teeth and handle combinations which, in my tests, subtly out performed similar Disstons.

    As to thickness tapering, I tested two similar toothed saws- one tapered one not. The un-tapered saw was noticeably heavier, which I liked by the way. As far as speed goes, both blades has similar set and blade thickness at the tooth line. So frankly, I didn’t notice any difference in speed. Maybe the heavier saw went a little better. As far as the blade sticking in the kerf or friction, kerfs that close need to get wedged open. The kenyon saws in the Seaton chest ARE taper ground, but very subtly; only a few thou each side. So again, I noticed no real difference in use.

    I’m not sure why saw makers tapered their blades. It seems a lot of work for not much, if any, advantage.

    Adam

  3. Rob Porcaro

    Chris,

    What an interesting historical reference from 1816! It makes me wonder if we’ve forgotten more than we learned over the centuries regarding hand tool work.
    I agree with Mike, above, in noting that Japanese saws have a similar, but opposite, taper. This seems unlikely to be a coincidence especially since the Japanese tool tradition was so reverential in preserving the function and spirit of hand tools.
    Here’s my take, for what it’s worth. The taper just feels right. One pulls (or pushes) the saw in the kerf pretty much horizontally. The tapered profile of the blade then automatically causes the row of teeth to produce a shearing approach to the wood at the bottom of the kerf. If all the teeth meet the wood at once, with the row of teeth moving parallel to the wood, in a "flat" approach, the saw wood tend to skip and jump. This is a somewhat like the shearing approach we all use intuitively with a file, a rasp, a chisel, or a plane. I believe the taper in the backsaw helps to "automatically" produce that sort of meeting of the saw teeth to the wood. That just feels right.
    I suspect that the LACK of the taper in new Western saws may be due in some cases not to informed preference but rather to having forgotten that hands-on feel. The sawmakers didn’t understand and figured, well, might as well make it nice and neat and symmetrical looking. Yet we still use these straight new saws, intuitively, with a bit of tilt, producing that shearing approach to the wood.
    My definition of tools: "extensions of the mind of the hand."
    Happy woodworking to all!

    Rob

  4. Mike Siemsen

    Chris and Gary,
    Gary states, "Your assumption is that form follows function." and then asks "But what if the reason is purely visual?" To which I must reply that I consider the visual to be functional aspect of a tool. All other things being equal I prefer to work with a handsome or beautiful tool.
    Mike

    By the way James, Jeff the cookie god is deaf and indifferent!

  5. James Watriss

    Whoops…

    forgot 2 important ingredients!

    (Damn you, Jeff)

    -1 tsp sea salt
    -1.5 tsp baking powder

  6. James Watriss

    OK, so maybe they cut good, but can you get them with plastic handles and a laser guide?

    : P

    Lacking mailing addresses and whatnot, my gift to the masses for the holidays: The best damned chocolate chip cookie recipe I’ve been able to come up with.

    -2 sticks of softened butter
    -2.25 C flour
    -.75 C brown sugar
    -.75 C white sugar
    -11 oz bag of toll house morsels
    -~4oz of the heath bar bits. (They come in an 8oz bag)
    -2 eggs
    -1/4 C Kahlua

    375 degrees, 12 minutes.

    I find that it helps to bake the cookies on aluminum foil, sprayed with PAM/olive oil/your aerosol grease of choice, and just slide the foil off of the cookie sheet and onto the cooling rack as a whole. My guess is that it keeps the moisture exchange down. Eitehr way, it seems to help the cookies stay soft for much longer. Also, thee cookies are very soft out of the oven, and it gives them something to hold onto while they’re being moved to the cooling rack.

    Last but not least, you must offer up the Obligatory Cookie Prayer. Have the children go outside, and yell out (at the top of their lungs) to the clouds:

    "O hear us Jeff, God of biscuits. Grant ye virtue to our oven, grant ye cleanliness to our fingers, and keep my parents away from my chocolate chip cookies, BECAUSE YOU DIDN’T DO THAT LAST TIME, YOU JERK!

    HARRUMPH!"

    I can’t say with scientific certitude that it really enhances the cookies, but it’s very entertaining. And if the batch comes out well, you’ll be in perfect position the next time to tell the kids "Well, it worked last time. Don’t mess with a streak."

    Of course, they may argue that it didn’t work, because he didn’t keep you away from the cookies. Just tell them that clearly, they weren’t loud enough, becuase he didn’t hear it all.

  7. Christopher Schwarz

    Gary,

    Of course, you could be correct. I have found that what usually happens with tools is that they start out "correct" and "functional" and devolve into poorer forms, like a bad photocopy of a photocopy.

    Take the bevel-edge chisel. The narrow side bevels are common and useful on early tools. As they became more mass-produced and distanced from the user they lost their correct functions. Now the bevels are so chunky that they are merely decorative.

    Chris

  8. Gary Roberts

    Mike, Chris, et al,

    Your assumption is that form follows function. There is also the unknown factor of form development by a combination of accident as well as trial and error. Not to mention the development of form as a function of myth and tradition. All of the above could pertain: built in depth stop, conservation of resources, decreasing flex of the blade). But what if the reason is purely visual? What if the saw maker wanted to make the backsaw resemble the panel saw with it’s tapered blade? What if we are all wrong and someone set the wrong type in a set of guild directions and from then on everyone made their backsaws with two different dimensions, toe and heel?

    I’ll stop now. I have a headache
    Gary

  9. Mike Siemsen

    Chris,
    Japanese saws cut on the pull stroke and are wider at the toe than the heel. I wonder if this isn’t a function of the fact that you can saw until the back hits the work at the beginning of the cut and still saw, rather than having the back hit in the middle of the cut. As mentioned above it also saves a bit of metal. I have also wondered if the narrower toe doesn’t make the blade a bit stiffer (closer to the back) in the beginning of the cut where you would need it.
    Mike

    Who just finished filing a nib into his Japanese saw (that will mess them up!).

  10. Mike

    This is something–the act of sawing with a taper-bladed backsaw–that I’ve spoke to a few people about. Summary is we all agree on its usefulness. Guess those guys knew what they were doing…

    Take care, Mike

  11. Gary Roberts

    Or… steel plate must have been one expensive commodity way back then. Why not trim the amount of steel used at the toe and leave a little more at the heel for the tote mounting? Plus they look cool, all aerodynamics and blazing fast cuts.

    Gary

  12. Bob Demers

    Interesting, I always assumed that this blade taper in width was due to poor sharpening techniques, not that it was done so at manufacturing time for a reason.
    I have a ‘few’ tapered in my coll,,er, user assortment, must give it a second thought next time I use one

    Bob, who can almost see his workshop accross the snowdrift

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