Why I put a ‘back bevel’ on plane blades…

Hello again,

Just recently, something came up that ‘got my goat’ and that was mention that a ‘flat back’ on a plane blade was good enough. Add in several “+1!” posts, and I couldn’t just leave it alone.

I mentioned that I don’t believe a ‘flat back’ = ‘sharp blade’ based on a ‘flat back’ being chock loaded with imperfections such as pits of corrosion, deep scratches and other nasties.

I got called on that, I suppose because I’m not ‘known to know anything’ and don’t write for any magazines, so what on earth would I know what I’m talking about. Right?

For your perusal;

Exhibit A;

If was can accept that this blade is generally flat, smooth and polished, then we’re in agreement. Obviously, I’m using a Pentax DSLR camera here…

Exhibit B;

The same blade, at the very edge under 200X magnification.

Note the deeper scratches on the right side, the small rust pits in the upper area, the relatively smooth and clean surface at the edge where there is a very small ‘back bevel’ put in place by use of a ruler on the stone, ala “the ruler trick”.

Chisels are a different problem altogether, and you pretty much have to accept the edge isn’t going to be ‘perfect’ but at the same time, a chisel isn’t usually as wide as a plane blade nor is ‘absolute sharp’ quite so important, unless of course you’re driving your plane through the wood with a hammer…

Any questions?


10 comments to Why I put a ‘back bevel’ on plane blades…

  • What is your preferred method for putting the back bevel on, and how much of a “time sink” is adding this to your routine (I use time sink pretty loosely here, i’m sure it doesn’t add much time)?

  • Hi Darren,

    It takes less time to put that ‘back bevel’ on the blade than it does to ‘prepare’ the back by any other method I know of.

    That blade has about 4 strokes on it, with a ruler on the right side of the stone, blade back touching the left side. And that was done only on the finest stone I own, a Gokumyo #20000.

    Depending on the stones you have, polishing the burr off the back can be easy, mildly annoying or downright frustrating (I used Shapton Pro stones here, put them in the ‘downright frustrating’ category) but even with ‘nice’ stones, it still takes more effort to get a lesser result.

    That tiny little bevel doesn’t affect relief angle, doesn’t affect operation of a chip breaker, doesn’t damage the stone, takes next to no time and helps make sure you’re left with as good an edge, right at the edge, as you can have.

    I confess, I often skip the ruler and just lift the blade up and do it by hand. The bevel is steeper, but not by very much. That blade actually had a ‘done by hand’ back bevel, and I erased it before I went through the motions of bringing the back to polished. It was gone in about a minute.

    So what I’m saying is that in all honestly, there is no real downside (unless you’re stuck in your convictions) and only benefits to be had. And if you do try it and are still not convinced, it’s an easily reversible procedure.

    If you haven’t done so already, try it yourself. Remember, only with the stone you use to finish with. Nothing more. ;)


  • David Weaver

    Several months ago, I made the same suggestion on another forum, that most people would get a better edge with a (this is added to the discussion) slightly steeper secondary bevel on the bevel side and a ruler tricked back bevel.

    The reaction I got was similar to what you got, varying from “I already sharpen perfectly” to “I’m offended that you think you can draw conclusions about my sharpening”.

    I don’t always, or even often do it, but it does create a more consistent edge because you’re always working with fresh metal on both sides of the bevel, and nothing deeper than the scratches of the abrasive.

  • Stu,
    Glad to hear you are enjoying the benefits of the “ruler” back bevel.

    The objections mostly seem to come from people who have not understood or tried it.

    The only modification I have adopted recently, is to do more strokes on the back bevel (on the polishing stone) to ensure that any wear bevel is removed.

    I do think the ruler (or other prop) is important for consistency

    Best wishes,
    David Charlesworth

  • Mathieu

    During a trip to Japan in december last year I met several reknown blacksmiths. Both Funatsu-san (Funahiro) and Metsugi create micro back bevels on there blades. We discussed this matter in depth and since I have been using it as well with very satisfying. Metsugi recommended an adhering aluminium tape instead of a ruler. Haven’t tried it but makes sense. The micro back bevel is so small that no other part of my sharpening technique needed adjustment. The bevel created on the coarse stone is there just as fast as it was before it seems.

  • Dave from VA

    This “back bevel” is not new. Way back in the 1980s, I attended Japanese tool, and Japanese woodworking seminars at The Luthierie with Robert Meadow. Makoto Imai was there from time to time, and it was always good information. Since most kanna come through with cutting angles of about 38 – 40 degrees (especially back then), Robert would put a very tiny back bevel on if he wanted to change the cutting angle on the plane for some unruly hardwood. It was so tiny, that it would disappear with the next sharpening, but given the very thin shavings attainable with properly set up kanna, it effectively changed the cutting angle. He could get many cutting angles for all kinds of wood without buying a dozen kanna.

  • Archie

    Won’t those same grooves or pits eventually mar the reduced edge of the micro back bevel, too. I don’t dispute your wisdom, just have too many older blades that leave serrations no matter what I do to create flat/linear intersections.

  • Dave,

    The low angle back bevel that I advocate and Stu seems to use, is about 2/3rds of one degree.

    It has nothing to do with raising effective pitch for difficult woods. This excellent technique is not to be confused with the “ruler technique” which is a sharpening method.

    best wishes,
    David charlesworth

  • Dave from VA

    Regardless, it was placing a back bevel on a Japanese blade during sharpening and was done by Robert Meadow a boatload of years before it was ever mentioned by anyone else (unless you can show an article from before about 1984). Also, you can change the cutting angle with a very slight back bevel – one doesn’t always need to make big changes for them to be effective.
    If you use the ruler technique to lift the back a little and create a narrow land at the cutting edge, the Japanese do that with the hollow in the ura side of the blade. Tapping out the blade controls the size of that land and there is no need for the ruler.

    Dave from VA

  • Dave from VA

    By the way, Stu, I enjoy your blog and tool website. I have been perusing around on them both for about a year. One of these days I will buy something but I have a bunch of Japanese tools, some of which are about 30 years old, and with the little amount of woodworking I have been doing it hasn’t seemed practical. You have one of the best selections for affordable, craftsman-quality tools I have seen recently. One of these days, you will be shipping some tools to Dave in Virginia.

    David, I have your book Techniques (vol II) and enjoyed it. I bought it several years ago. If I used western tools, I would gladly use your ruler method, but I can get very narrow lands on the backs of my Japanese blades (at the edge)and don’t really need the ruler.

    Dave from VA