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.