Chris Schwarz's Blog

You Call it Dubbing; I Call it a Back Bevel

One of the great mysteries of the hand tool world is how Roy Underhill never seems to get older. (Is there a cursed painting in your attic, Mr. Underhill?) The other great mystery is about the unbeveled faces of vintage irons in handplanes.

If you’ve even bought an old plane you know of what I speak. You take one look at the face of the iron (what some people call the “back”), and it looks like crap. This flies in the face of modern handplane dogma. That surface is supposed to be flat and polished so our ancestors could see just how rotten their teeth were.

About half the time the face of the iron looks untouched. The other half of the time it looks like they dubbed over that edge , rounding it over. Bad form, no?

Plane pundits I know have speculated that this is the result of the plane falling into inexperienced hands after its previous owner retired and died. Or perhaps it was a carpenter’s tool that planed softwood and didn’t require a super-keen edge.

I have another crazy theory. Perhaps in some of these cases the woodworker had dubbed the face intentionally to create a back bevel.

Why would anyone do this? To increase the pitch of the plane and reduce tear-out. The higher the pitch, the less tearing. And because bevel-down planes are somewhat fixed at a 45�° pitch, the only ways to increase your cutting angle are to get a new higher-pitched frog (a modern option for Lie-Nielsen plane users) or to apply a back bevel.

I have some smaller Stanley-style planes that I quite like. A No. 3 Bed Rock and a No. 2 Lie-Nielsen. Both have 45�° frogs, which makes them unsuitable for reversing, interlocked or curly grain. So I polish a 15�° back bevel on those tools, which transforms them into a 60�° tool.

With the help of my cheapie honing guide, this is easy and repeatable. After honing the bevel, I’ll flip the iron over in the guide, set it to 15Ã?° by sighting it against a block of wood (someday , how about today , I’ll make a jig to set it automatically), and chase the burr off on an #8,000-grit waterstone.

It adds about five minutes to the sharpening time. And that’s well worth it because removing tear-out takes a lot longer than that. Give it a try on your 45Ã?° planes and test it on some mahogany with interlocked grain. Work against the grain (like I am below). I think you’ll be impressed.

– Christopher Schwarz

18 thoughts on “You Call it Dubbing; I Call it a Back Bevel

  1. Thomas Hamernik

    Thanks, Chris-

    I understand that a large included angle (one that is greater than about 35 degrees) dulls peceptively more quickly. With a 35 degree secondary bevel and a 15 degree back bevel, you have an included angle of 50 degrees – substantial. Are you noticing any need for more frequent sharpening?

    TJH

  2. Christopher Schwarz

    Thomas,

    The bevel facing down doesn’t affect the cut — as long as you don’t violate the clearance angle. It is out of the equation for the most part.

    So no. I hone a 35° secondary bevel on the bevel facing the wood. Then I hone a 15° back bevel. On a 45° frog this is is a 60° angle.

    Hope this makes sense.

  3. Thomas Hamernik

    Are you altering the main bevel to maintain a "normal" included angle (such as 25 or 30 degrees)? So, if you add a 15 degree backbevel, are you regrinding the main bevel to 15 degrees, as well, to keep a 30 degree (15 + 15) included angle and avoid increasing it to 45 degrees (30 + 15)?

  4. Christopher Schwarz

    Bill,

    The evidence I have from back bevels is from the physical record – 19th century planes that have dubbing on the backs.

    High angles were well understood. Even in the 17th century. But I haven’t seen back bevels discussed specifically. But dag-nabit, now I’m going to have to look.

    Holtzapffel here I come.

    Chris

  5. Capt Barnacle

    The reason Roy doesn’t age is because he never changes his style. He still looks like a 80’s porn star with tight jeans and a bushy mustache.

  6. Ron Hock

    Good post! I’d like to add to the common knowledge by referencing my blog post: "Back Bevels and Plane Geometry" (http://tinyurl.com/yaroppd). And I’d especially like to mention Brian Burns’ book, Double Bevel Sharpening, which goes in to considerable detail about the angles and how to get them. He even discusses the advantages of back bevels on jointer and planer knives as well. (Book available here: http://tinyurl.com/ylye9lq)

  7. Bill Melidones

    Chris,
    Isn’t this Charlesworth’s ruler trick with a higher angle? So this "new" trick could have been around for 2 centurys? Have you or Joel found it in any of your research of 19th century woodworking techniques?

    BTW I just reviewed your new DVD Handplane Basics.
    My Plane sharpening time is now a fraction of what it was, thanks.

  8. Cosmo

    Interesting article! For a really high angle (approaching a scraper) you can always turn the blade around, which will give you 70 degrees and up. A little fiddly to set up with the chip breaker, but it works!

    Cosmo

  9. David Cockey

    Another reason for a back bevel on a plane blade is it eliminates the need for a flat, polished back to obtain a sharp edge. Only the back bevel needs to be smooth. If you don’t want a higher angle then use a low angle back bevel.

  10. Christopher Schwarz

    Dan,

    I have not found that to be the case. The polish on the back needs to be only a tiny amount to do the job. So the mere act of polishing the back bevel allows it to reassert itself at every sharpening.

    Chris

  11. Christopher Schwarz

    Mike,

    Yup. Just five strokes. Doesn’t affect the camber (if you have any).

    Chris

  12. Brian S

    This post has impeccable timing. I’m in a pickle with my b-day gift certificate to LN. (I know, good pickle) My lovely wife just surprised me with a #8 at LN show in Seattle last Sat. and that leaves me with a "FINE" tool to pick up. (Just watched your Rough, Medium & Fine DVD – very good btw) So Christopher, if you where in my shoes, would you get a LN 4 1/2, or their low angle smoother and put a secondary angle on it? I know you’d say it’s personal preference, but the LA smoother is $100 bucks cheaper and I still need to pick up some Shapton stones 🙂 Thoughts?

    P.S. if this is the wrong venue for this sort of question, i apologize for detracting from the subject.

    Brian S
    Seattle, WA

  13. Dan Pope

    I recently applied this technique when flattening my store bought bench top. I ran into some areas where the grain in adjacent laminated boards ran in opposite directions. The 60 degree angle of attack worked well in my 07 jointer but as expected was much harder to push. I solved the problem by setting up a second blade at normal pitch and moving to the higher pitch for those areas with tear-out.
    Question: If you only take a few strokes on the 8000 stone for the back bevel will the next sharpening of the primary bevel be enough to remove the back bevel, returning the back to a flat non-beveled state?
    Dan

  14. Mike N

    Man, this seems so obvious that i feel like a dummy not working this out on my own. For some reason, i didn’t previously connect "back bevel" with "increased relative pitch". I’m dumb.

    So are we talking 4 or 5 swipes on the #8000 grit? Treat it just like you would remove the burr flat on the stone? Do you have to do anything special if you have a slight camber on the iron?

    Mike

Comments are closed.