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Love Your Saws with Matthew Cianci


 
  Rake and a Rip Saws… 1 of 2  

The first time I got my hands on a proper rip saw was, unfortunately, a bitter-sweet experience.

It was sweet because it was the first moment of the rest of my woodworking life….like a door had been opened to a place that was fun, fulfilling, and free from the threat of lung cancer and systematic dismemberment. But it was bitter because I was frustrated with the performance of the saw… and just so you know, the saw wasn’t from Home Depot or Ace Hardware. The saw was a vintage Disston D-8 with a thumbhole from the classic 1896 to 1917 era…we’re talking about the greatest rip saw ever made by human hands. And it was professionally sharpened by a well-respected saw guru.

So what was the problem?

Well, the saw was gorgeous, perfectly tuned, sharp as English wit, but to my inexperienced hands, every time I stroked the saw through wood, it was not a pleasant experience. The teeth felt like they were sticking in the wood…and like I had to push really hard to get them to cut. I could feel the moment each tooth sheared a chunk of fibers from the board, and that feeling reverberated from the teeth, to the saw plate, to the tote, to my palm, and up my arm to my shoulder. It was jittery and rough and un-nerving. And I was pissed.

What the hell?!?!? This was not the zen like experience I had read about in the pages of books and magazines…this was a hands on demonstration of why people started the asinine folk art craze of painting on hand saws instead of using them!!!

Well, like most things in life, it turns out knowledge really is power. And in this case, the knowledge I didn’t have about rip saws was disempowering me to use them. What I quickly learned was that hand saws, much UNLIKE powered saws, require an intimate knowledge of their form and function to use properly. Any toothless caveman can go to Home Despot, buy a $99 table saw, plug it in, and be ripping white oak all day long like he was Norm Abrams. But to do so with a hand rip saw requires knowledge of the physiology of wood, body mechanics, and saw tooth geometry.

So which one was I missing?…..the one about saw tooth geometry, and in this case, that was the most critical absence. You see, what I did not yet understand about rip saw teeth was the fundamentals of tooth rake. And the rake was what was making this saw cut like a jack hammer.

Rake, or “pitch” as it also is traditionally called, (not to be confused with the common, modern designation of pitch meaning tooth spacing) is the measure in degrees that the face of each cutting tooth is rotated back from 90 degrees relative to the tooth line. The illustration below (from Disston and Sons “Lumberman Handbook”, 1907) demonstrates two different rakes.

In the first image is shown a saw with 0 (zero) degrees of rake. The face of each tooth is 90 degrees to the tooth line, and in effect not raked forward (like Japanese saws) and not raked backward.

In the second image is shown a saw with 12 (twelve) degrees of rake, meaning that the face of each tooth is rotated back 12 degrees from vertical (90 degrees from the tooth line).

So, what’s this have to do with how a saw cuts? Lots. And lots. And….well, you get the idea. Which is this: the greater the teeth are raked back from vertical, the less resistance the teeth encounter as they cut the wood. So teeth with zero rake–meaning the cutting faces of each tooth are 90 degrees from the tooth line–will cut more aggressively and meet with more resistance than teeth that are raked 5 degrees back from vertical (relative to the toothline). Make sense? Good.

I should also point out that the more teeth are raked back, the less aggressively they cut. So before you go and file 25 degrees of rake into all your rip saws, you should know that by doing so, you’re effectively turning them into giant bread knives. Not good for wood! So, can you guess how much rake was on the teeth on that fortuitous first D-8?

Zero degrees. And if you’re paying attention at home, you now know that means that the face of each cutting tooth was 90 degrees from the tooth line…just like in the first illustration above.

And that’s why my first nice rip saw–though perfectly tuned and filed with a precision that would make even ole Henry Disston proud–made me want to call the guy I sold my table saw to and beg him to sell it back to me!!!!! But I didn’t give up. In stead, I started filing my own saws and here’s what I figured out…


 

1 of 2

 

English Saws



Dovetail Saws


  

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