Chris Schwarz's Blog

Rehandling a Chisel

For the last week or so I’ve been researching the science of smacking the snot out of things.

I’ve
been reading lecture notes from a Harvard course on “fracture
mechanics,” learning what the Timber Construction Manual has to say
about “design values for bearing on end grain” and hearing about the
construction of escrima (a 2′ stick for whacking people) in the martial
arts.

After taking all this in, there are a lot of different
things I want to try when I replace handles on my chisels in the future.
However, I need to get to work and so today I took the most direct
route in rehandling my 1/2″ mortising chisel.

Before the
squealing begins, please note that this is my Ray Iles chisel, which I
really like and would purchase again. Did I abuse the chisel? No. I was
using a wooden mallet. Was the chisel sharp? Yes. Was the chisel
defective? No, but I do think the wood for the handle could have been
chosen with more care.

So let’s start with the wood selection.
The original handle was beech, which is tough and traditional. After
looking at all the handles in my set, I realized that the two handles
that cracked had grain that was running at an angle from end to end. The
handles that were not cracked had dead-straight grain.

You can see how the grain runs out in this photo of the cracked interior, which shows the tang.

For my replacement handle, I chose wood that was as straight as I could manage. Instead of beech, I decided to use American Hornbeam (Carpinus caroliniana),
which also goes by the aliases ironwood, blue-beech or musclewood. I
have mortising and bevel-edge chisels made of this stuff, and I’ve
managed only to take a chip out of one in 2005 (this is what Lie-Nielsen
Toolworks uses).

I took my cracked handle apart with care so I
could see how it was put together at the factory in England. Its tang is
an untapered bar of D2 steel measuring .497″ x .590″ x 2.375″. From the
looks of the handle, I think the factory bored a 5/8″-diameter hole
that’s 2.6″ deep into the handle. Then they drove or pressed the
rectangular tang into the hole, crushing the fibers in the corners,
wedging the tang in the wood.

I decided to do exactly the same
thing. I bored the hole to the same spec as the original handle. But it
was difficult to get the tang started into its hole. So I took a chisel
and pared the beginning of the hole to the same shape as the tang.

Then
I cut out a leather bolster to sit between the handle and the chisel.
Some woodworkers will say this is an unnecessary step. That’s fine. Do
that with your own chisels. I like me some leather. No, I’m not listening. Nunga, nunga, nunga. I can’t hear you… .

I placed the
leather over the tang then pressed the new, unshaped handle onto the
end of the tang. I clamped the chisel in my vise and knocked the new handle into place with a 16-oz. hammer.

Then I shaped
the handle. First with a drawknife. Then with rasps and sandpaper. I did
most of the shaping with a drawknife, creating the tapered and ovaloid
shape of the handle. The handle tapers from the top to the leather. It
is oval in cross-section, with the long part of the oval in line with
the bevel of the chisel and the short part of the oval in line with the
flanks of the blade.

I knifed the handle until it was less than
1/16″ proud of the chisel’s bolster. Then I trimmed the wood flush to
the bolster using rasps. Then I used the rasps to round over the
striking end of the handle. A little sandpaper and linseed oil finished
the job.

I have other crazy plans for a second cracked handle. So don’t stray too far.

— Christopher Schwarz

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