Plane Facts

Plane one big and one smallNow that I’m officially on board I figure I’ll get the obligatory plane post out of the way early. Sure, I did my touchy-feely First Day post last week. And while I was in the PopWood offices (I’m back home in Penn. now until we make the final move) I got a chance to play around with Jet’s new 719200 lathe (read a little about it here) in order to review it for the October issue of the magazine. Now some would say those are “official” blog posts but I understand you are not “really” an editor until you’ve posted about planes.

Plane flatness check

For quite some time I’ve heard about lapping the sole of a plane in order to get it absolutely perfectly flat. Hogwash. Sure, flattening a plane can make life easier but it just isn’t a “necessity.” Those who think a plane is useless without being perfectly flat just don’t understand what a plane is or how it works, and they certainly don’t understand the tolerances of the medium in which we work. With all that said, I’ve never flattened a plane.

I’m a pretty meticulous woodworker but I only work to the nearest 1/32″. If my plane measures within that tolerance of being flat, I’m OK with it. I’ve always thought flattening planes is a waste of good woodworking time. If a plane is that far out of flat, throw it away and get another. If it’s an old plane, it just means someone abused it. If it’s new, it’s a defect.

Plane of choiceThe biggest problem I have with flattening planes is, my plane of choice is just too big to flatten. From what I’ve read, people spend days flattening a simple smooth plane. How long is it going to take for me to lap this to perfection?

Whether your plane is hand or power, you really only need to know a few things. For a handplane, three points need to be in the same plane: the toe, the area right behind the mouth and somewhere toward the back of the plane. Honestly, you really can get away with two of those. The only one that has to remain is the spot right behind the mouth. It means you may have to learn how to apply pressure differently as you use the plane but it will still work. Sharp is far more important than flat. I don’t care what method you use to sharpen. Just pick the one that makes the most sense to you. Whether it’s a really old method of sharpening, mine or someone else’s, just sharpen.

For my plane of choice, I merely need to make sure my knives are parallel to my outfeed table and that my outfeed table is in line with the apex of the arc of the cutterhead. Once I achieve that, everything else is fairly inconsequential. Again, sharp is far more important than flat.

I may have oversimplified things a bit but it is my first “official” editorial post. One of the biggest problems I’ve seen with woodworkers over the years is, they worry the minutiae to death and don’t get to do what’s important: woodworking. Get into your shop, sharpen (because that’s far more important than flat) and set up your tools as quickly as possible and build something. If you do it often enough you’ll get better or you could spend all your time worrying about your plane being “a couple of thou” out of flat.

— Chuck Bender

p.s. If you just can’t bear to replace an old handplane and would prefer to give it new life, check out Christopher Schwarz’s DVD “Super-Tune a Handplane: How to Turn a Flea-market Find into a Fast, Accurate and Smooth-cutting Tool.

34 thoughts on “Plane Facts

  1. Milford

    I don’t understand the emphasis on “behind the mouth.” Was that a typo? Or just applicable to the powered jointer? Certainly the area just ahead of the blade of a hand plane should be holding the workpiece down until the blade comes along to lift a shaving; otherwise the wood can split ahead of the cutting edge. Just look at the way a Japanese plane’s sole is configured, with the intermediate areas, including that following the blade (OK, so Japanese woodworkers use what we would consider backward terminology, referencing it to the body of the user rather than direction of travel) are slightly relieved to minimize contact friction, eliminate unnecessary flattening tedium, as well as controlling the cutting process. In my experience, whether from faulty manufacture or age-warping, the area following the blade of an old (occasionally new) metal-bodied plane can be lower than the front edge of the mouth, requiring the blade to be extended too far for proper control of the cutting. For more on this, see pages 151 and 160 of Scott Wynn’s “Woodworker’s Guide to Handplanes.”

    1. Chuck BenderChuck Bender Post author

      It was not a typo and it is not necessarily applicable to a powered jointer. The reason I say “behind the mouth” is that area of the sole helps support the blade. If the front of the mouth was the important part of a plane, chisel planes would never work and how could a plane with an adjustable mouth keep within tolerance?

  2. AstraGal

    Chuck, you are so right, and not alone in your thinking. Here’s the Ron’s Remarks column from Ron Herman’s May e-newsletter:

    FLATTENING THE SOLES OF BENCH PLANES
    I talk to a lot of students who are convinced the only way a bench plane can be useful is for the sole to be completely flat. They invest a lot of time and money to grind those soles to insane engineering tolerances, when It’s not necessary at all. These cast planes were never even sent from the factory utterly flat!

    For the plane to work properly, the toe, heel and mouth behind the blade must be flat in a geometric plane in regard to each other. That’s it. That is where it is important for them to contact the wood. For evidence of this, look at corrugated planes. How could they possibly work – and they do – if they had to be completely flat with complete contact?

    Complete contact causes friction and may add drag to your stroke, causing you to work harder for the same effect. Do yourself a favor and stop flattening the sole when those three areas are flat, and use the rest of your time to make more shavings.
    – Ron

    PS – We recently fettled up some garage sale planes with our students and flattened the soles in this manner. They were shaving .001″ rivings in short order!

    1. mmyjak

      Well, I guess I have to provide a slightly dissenting point of view here w/ Ron, et.al. I contend that the elevation of the front or ‘toe side’ of the mouth of a hand plane is THE defining point in describing the geometric plane between toe and heal. The point behind the mouth, not so much. Here’s why –

      The front of the mouth is responsible for ‘holding the wood fibers down,’ thus preventing ‘lifting’ and thus errant tear-out of the wood. Think of a hand plane as a chisel in a jig. Why not just use a chisel (instead of a plane) to surface wood? The answer is a total lack of control. Roy Underhill gave a great explanation (and demonstration) of this on his show some years back.

      Yes, one could argue that the ‘heel’ side of the mouth lends support behind the cutter, but also in conjunction with the frog and cap iron. Lack of support in any of these areas can lead to chatter and tear-out. I would argue that if you look closely at any bevel-down mounted plane iron, you’ll quickly see that there is quite a gap between the back of the iron and the heal-side of the mouth (often measuring in the 10’s of thousandths of an inch.) QED.

      So to my mind, the critical gap that defines the thickness of a shaving is the distance the iron ‘hangs’ or extends below the geometric plane defined by the heel, toe and toe-side of the mouth.

  3. cbf123

    “For a handplane, three points need to be in the same plane: the toe, the area right behind the mouth and somewhere toward the back of the plane.”

    Don’t know about others, but when I hear about someone flattening a plane sole, the _whole point_ of the exercise is to ensure that the above is true.

    I don’t know of a lot of people that lap till the entire sole is flat.

  4. davem0121

    Chuck I know what you’re thinking, ’cause right now I’m thinking the same thing. Actually, I’ve been thinking it ever since I got here: Why oh why didn’t I take the BLUE pill?

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