In Chisels, Chris Schwarz Blog

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As a beginning dovetailer, I had a crappy set of plastic-handled chisels, a newspaperman’s salary and a copy of the Japan Woodworker catalog.

All three things conspired to make me miserable.

I wanted to cut dovetails with bold angles, but my crappy chisels had side bevels that were as big as Cheddar Mountain at Bonanza. So every time I went to clean out the waste between my tails, the side bevels would tear a bite out of my tails.

I wanted to buy a sweet dovetail chisel from Japan Woodworker that didn’t have side bevels. That would allow me to sneak into the corners with ease. But I had a newspaperman’s salary, which made me want to sell drugs to the local Junior Leaguers.

Luckily, I met some clever people in my travels. Dovetailing demon Rob Cosman showed me his hot-rodded chisel on which he ground the side bevels down to nothing (and he shaped the chisel with a fishtail sweep , something I’ll share another day). Woodworker Lonnie Bird showed me how he lopped the end off a plastic-handled chisel and reshaped it so that it was easy to strike.

And what did I bring to the equation? I figured out chisel geometry (like most woodworkers eventually do), which allowed me to make the tool take a beating like a rented mule.

Here’s What You Do
So if you have a nice four-figure salary and can spring for one of the nice $1 chisels at the flea market, here’s how you can make it into a sweet worker in about 30 minutes.

Step one:
File the side bevels. The side flats below the side bevels on cheap chisels are way too big for dovetail work. You need to file the bevels so that there is absolutely zero flat area on the long sides of your chisel’s blade. When you are done, the chisel’s blade should look like a decapitated pyramid in cross-section.

You can do this with a grinder, a stationery belt sander or a disk sander. Or you can take the cheap (and safer) way out and use a multicut file. This file, which is generally used for shaping metal, can shape the side bevels of a typical chisel in about 10 minutes.

Secure the chisel in a vise and work the side bevels with the file. Hold the file with two hands: one on the tang and one at the tip. Cut only on the push stroke. And stroke the file so your hand is never (ever) right over the cutting edge of the chisel. One slip and you are (blood-soaked) toast.

After filing the side bevels so they extend to the flat face of the chisel, clean up your work with light stokes of the multicut file. Then clean up your work (if you like) with a fine file or sandpaper.

Step two: Adjust the handle. If the striking end of the handle is rounded and plastic, it is likely too top-heavy to wield comfortably (the chisel should feel like a pencil), and the rounded end is probably tough to strike without your mallet glancing off the end oddly.

Take a hacksaw and cut off the top 3/4″ of the handle. Try the balance. Still feel top-heavy? Lop off a little more. Make sure you leave enough handle so you can grasp the handle in your hand to strike it without striking yourself.

Once you get the balance right, file the top of the handle flat and dress the sharp corners to remove any odd burrs.

Step three:
Sharpen it correctly. Grind the primary bevel of the tool at 25Ã?°. Then grind a 35Ã?° secondary bevel on the very tip. It will be a very small secondary bevel, which is a good thing. The advantage of this steep bevel is that your tool will be durable through a lot of chopping. A steeper honing angle increases edge life. And the steep angle isn’t a detriment to chopping out waste , it scarcely feels different than a 25Ã?° chisel.

Then you are off to the races.

Try this with an inexpensive 1/4″ or 3/8″ chisel and I think you’ll be pleased with the results , especially the lack of damaged tail boards.

– Christopher Schwarz

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Showing 9 comments
  • Ron Godbout

    This is a great low-buck tip, but as a safety engineer, I have to comment on using a file by holding the tang and tip. A file should NEVER be used without a handle over the tang. I’ve seen some pretty grisly hand injuries from unguarded file tangs over the years. Please advise your readers accordingly. Thanks.

    Ron Godbout, CSP
    Northfield, NH

  • ike

    good article but the chisel used i’ve been looking for cant seem to find a nice set of six though seems everyone has these i like the way they look thats why i want the set.

  • Kelly

    Hey Chris,

    The best thing I have done so far was cut off the top of my Pfeil beveled edge chisels. They are way more comfortable and have better balance. I also attempted the Lonnie Bird maneuver of grinding down the side bevel of a 1/4" chisel on a power grinder. All I got to say is be careful. It doesn’t take much before you’ve really messed up! I like the file idea much better as I think I would have more control. Thanks!

    Kelly

  • R Francis

    http://www.hand-cut-dovetails.com/tools/8chisEgs/edges.html
    Digging around on this site will give you a detailed description of how to grind fronts and backs to make a dovetail chisel.
    Very precise and informative.

  • Christopher Schwarz

    Derek,

    The Buck Bros., Greenlee, Swans, Whiterbys and other 19th-century chisels I own have side bevels that are as small (or smaller) than those on a Lie-Nielsen.

    The kerf left by the saw accommodates the small side bevels.

    There are ways of angling the tool to avoid the problem, which is why you can use even a firmer for the job, but I like chopping straight down.

    Thanks for the comment.

    Chris

  • Derek Cohen

    Hi Chris

    There are very few chisels that I know of that have sharp side edges. Lie-Nielsen, Blue Spruce, a couple of Japanese brands.. How was it done in days of olde with flat-sided pairing chisels? It strikes me that the appropriate technique was not to attempt to chop into the corners directly, but to size the chisel to the centre of the tail (or pin), clear this out, then return and clean out the angle, perhaps with a skew or fishtail.

    Regards from Perth

    Derek

  • Rob Porcaro

    Chris,

    Another good approach is to dress the sides of a firmer chisel (or a bench chisel with high sides) to 75-78 degrees to allow clearance in the dovetail spaces. This avoids harsh arrises at the meetings of the angled sides and bottom of the chisel. Only the first inch or so of the chisel needs to be altered. Japanese "arinomi" style chisels, sold by Hida, have this geometry.

    Here’s links with more detail:
    http://www.rpwoodwork.com/blog/2008/09/28/chopping-dovetails/
    http://www.rpwoodwork.com/blog/2008/09/28/more-on-dovetail-chisels/

    Just another way to skin a cat.

    Rob

  • Christopher Schwarz

    Chris,

    Good files are harder than Rockwell 62 (on the C scale). Inexpensive chisels are almost always softer.

    I’ve personally tested the hardness of more than 20 brands of chisels and they range from Rockwell 55 (which is too darn soft) up to 60. So typical quality files do just fine.

    This chisel (which I tested years ago) is from a set of Marples that tested at Rockwell 59.

    Chris

  • Chris F

    I’m surprised that a file will actually work on a chisel–I’d thought they were pretty close in hardness.

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