“The ole’ high angle plane trick” or UNE SECRET DU METIER
More than once in my youth I was reminded that “a tradesman gets paid for what he knows, and if a tradesman tells everyone the secrets of his trade, people won’t need to employ him”.
Trade Secrets. Les secrets du metier. The arcane minutia. Things that you only share amongst brothers in craft.
The bad news is that many of those secrets have been misplaced, not lost, just misplaced. The good news is that in the age of information we’re living in, there’s more arcanery being shared than ever before. And, hopefully, everyone will be the beneficiary.
I recently watched an episode of Underhill’s Woodwright’s Shop with Brian Boggs. During the course of the show, Roy commented on a spokeshave that Brian had modified for working figured or otherwise “gnarly” wood. It was a concave shave. Brian had simply turned the iron over and placed the bevel up. But…here’s the secret, he had turned a small burr on the edge. Most people associate “burr” with scraper. But remember the definition of a scraping tool is a cutting edge that is unsupported (or minimally supported). In the case of Brian’s secret spokeshave, he has actually created a “high angle” sheering tool. Here’s the geometry that makes it work:
By simply turning the iron over and positioning the bevel “up”, we’ve increased the effective cutting angle to 70 degrees. Now, it’s a pretty well accepted notion that a cutting angle (or “attack angle”, si vous prefere’) of 62 degrees, or so, is ideal for sheer cutting figured wood. So, it should go without saying that, we have to reduce the angle by 8 degrees, give or take a skoch. The quickest way to do is by turning a burr of 8 degrees, or so. (By turning a burr, we can maintain the ground angle on the iron at 25 degrees, giving us a reasonably strong section.
“The ‘right way’ to do anything is the way that works best for you”
So here’s what happens when we put all this scientific thinking into play:
Well, we know it works on rounded surfaces, so how does it do on the flat? Let’s see:
Okay, here’s the really interesting point here. This lil’ ole’ Union plane has been sitting on the shelf for a couple of years. The iron hasn’t been sharpened in the same amount of time. I DID NOT turn a hook (burr) on the blade, so when assembled it will have an effective cutting angle of something HIGHER than 70 degrees. Transitional planes are notorious “chatterers”. Yet the picture below says it all. Same piece of curly maple and the only blemish on the “complexion” of this board is where the worms decided to take up residence.
So, there it is, another mystery uncovered and another item for your ever growing “bag-o-tricks”. But remember, all tricks take a little time to master, so don’t get discouraged if it doesn’t give you “masterpiece” results the first time that you pull it out of your bag. You gotta work a little to make it “your own”.
The next time you pick up an old plane and see the bevel pointed skyward, you’re gonna have to ask yourself “did the dealer just not know how this thing was supposed to go together or have I got a tool that was once held in the hands of a ‘master'”?
And always remember “It’s a poor workman who blames his tools – Gramps”.