Chris Schwarz's Blog

A Foul Mouth Will Get You in Trouble

Sometimes it seems like there are 100 things that can go wrong with a handplane before it will do one thing right: Eject a perfect and fluffy shaving.

Lately I’ve been using a lot of bevel-up planes on softwoods and have become attuned to some of their peculiarities. Maybe I’m the new dumb kid on these issues; if so, then this blog entry will just be a note to myself.

Dust and Clearance Angles
Though we handplane users boast that our tools don’t make dust like a power sander, I think we all know that’s not really true. Planes make a very fine dust , they just don’t make enough of it to send you home hacking and digging things out of your nose that look like props from a Roger Corman movie.

This dust builds up on the work and on the tool and, in my experience, can become a problem, particularly with bevel-up tools such as block planes, some miter planes and the ever-popular bevel-up smoothing planes.

Here’s what I’ve found: This fine dust builds up behind the cutting edge and the back of the tool’s throat (see the photo at the top of this entry for an example). Surely this part of the plane has an anatomical name (like toe, heel, throat, cheeks etc.). So I will name it the plane’s “uvula.” Dust builds up in the uvula and , left unchecked , it will make bad trouble.

Here’s why: In a bevel-up plane the uvula is smaller than on a traditional bevel-down plane. The bevel-down planes have a huge drive-a-Vanagon-through-it uvula. The bevel-up planes have a petite micro-uvula.

When enough dust builds up, the tool tends to stop cutting until you clear out the uvula. Why? I think the dust makes the plane violate the tool’s clearance angle. In essence, the dust interferes with the cutting action. In a plane that is working well, the iron compresses and then cuts the wood’s fibers , then the remaining fibers spring back into the uvula. If you’ve got no uvula, the fiber springback from the wood pushes the iron out of the cut.

Am I full of potted meat in a round, sheet format? Perhaps. But clear your uvula next time and drop me a line.

Running Over Dead Bodies
Nothing fouls a plane’s mouth faster than trying to plane over an errant shaving on your work. The shaving crams in the mouth and tool stops cutting.

This is why I’m careful about shaving ejection. When I can, I’ll nudge the shavings into the garbage can at the end of my bench at the end of a stroke. Or I’ll skew the plane a bit and use my pinky to snowplow the shavings away from the sole.

If my shaving is thick enough it will spill out onto my left hand, which I’ll shift to direct the shaving someplace where it won’t get re-planed.

A Big Mouth
Some planes get clogged when they have an open mouth and are taking a fine shaving. The shavings build up in the mouth and get pushed down and out the mouth and into the path of the blade. Then the mouth is instantly fouled like when you run over a shaving.

So a tight mouth (just a bit wider than a typical shaving) is an asset. A big mouth will generally get you in trouble in planing (and in life).

– Christopher Schwarz

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15 thoughts on “A Foul Mouth Will Get You in Trouble

  1. ocd

    Geez, I never thought of or considered dust from my planes. A naive fool like me shouldn’t even be allowed to ownn such nice tools as Lie-Nielsen. I did find the comment about the rounding of the throat interesting. And thanks to my computer guru for helping me post this. ocd

  2. Christopher Schwarz

    Momo,

    That plane is still wicked sharp. I can get end-grain shavings in pine. I think planes make some dust.

    Chris

  3. David

    You can take the anatomic analogy further if you like. The Mallampati Classification scheme is based on the position of the uvula in relation to the other soft tissues of the oral cavity. Have fun classifying your planes/colleagues:

  4. David

    "David, why would you be irritated at users of bevel ups? These are indeed superior planes when you understand how to use them and let your bevel down prejudices go :)"

    I’m not irritated at users of bevel-up planes – I have several. They’re wonderful tools for planing end-grain. But they are not the second coming. Stanley made these in the late 19th and early 20th century, and craftsmen back then were not stupid. Stanley sold quite a few – for planing end grain.

  5. Momo

    David, why would you be irritated at users of bevel ups? These are indeed superior planes when you understand how to use them and let your bevel down prejudices go 🙂

    Chris F, you can adjust the depth of cut on the go with thumb and index of left hand cupped over the blade. Becomes natural after a bit of practice. Also, you can really hog with the Jack, try it… I routinely peel off 3/32 hardwood slices for marquetry. You need a steady bench and push from your abs, not arms.

    Finally, Chris S, when you see dust when planing, it’s time to sharpen…

    Hugs from Momo

  6. Chris F

    David, like anything else there are tradeoffs. Up in the Canadian prairies I cannot find decent secondhand planes and buying via ebay from the US is expensive due to shipping across the border. Since I was starting from scratch it made a certain amount of sense to go bevel-up, at least for now.

    I started with the jack for endgrain and general use and also used it as a big smoother and small jointer. When I made my workbench I got the LV jointer because it was the biggest one they had, and was far cheaper than the L-N #7. Recently I picked up the smoother. The price wasn’t really an issue (only about $10 cheaper than a 4/ 1/2), but the fact that it’s bevel-up allows me to easily set steeper angles for figured woods. On a bevel-down plane I’d need to mess with the cap iron to backbevel the blade when sharpening. The fact that all three can share blades adds a bit of flexibility, but isn’t a huge deal.

    Sure there are tradeoffs. I can’t adjust depth of cut while planing, and the jack doesn’t do as well for hogging off material (I’d like an old #6 for this).

  7. David

    Interesting – yet another disadvantage of a bevel-up plane. Please keep serving them up. I find nothing wrong with a bevel-up plane for their original purpose – planing end grain. But it’s more than passingly irritating to read the chorus of "bevel-up planes are better than any other design" comments on weblogs and net forums.

    It isn’t so, of course. But because it’s a human characteristic to self-justify our choices, and because those usually trying to justify a bevel-up plane as a superior design rather than a preference are cheap (bevel-up planes are less expensive because they don’t have a frog), newbies really do get the idea (wrongly) that it’s just old-fashioned and slightly daft to prefer a bevel-down design.

  8. Alex Grigoriev

    Chris,

    What you really need is to slightly round and polish the rear edge of the throat. That’s what gives you dust. Repeat if it gets scratched too much again.

  9. Verne Mattson

    I like the uvula analogy. I would suggest that the whole planing action is more in the alimentary canal realm, with dust acting like fried food.

    Good shavings? Plenty of fiber…dust? Increase your fiber intake.

    So it seems…

  10. Ethan

    I agree with Dan on both accounts.

    And I hope my dad never hears me say I clear my uvula with a 4" china bristle brush.

  11. Dan Pope

    Chris
    When I watch experienced "planers" in action their front hand is always in motion removing shavings from the planes mouth after every stroke. When I let the shavings build up in the mouth then ultimately one of the consequences that you so eloquently describe becomes inevitable. Also I have found that a 3-4" china bristle brush used frequently as demonstrated by David Charlesworth does wonders to keep the "uvula" clear.
    Dan Pope

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