a small response to years of subtle but predatory marketing on
PBS that has newcomers asking about mortising machines for their
early projects, I prepared a short primer this morning in the
shop to answer a younger man’s question. The entire session,
including stock preparation and photography, took 30 minutes. The actual mortise chopping took 4 minutes, and I wrote this up
on my lunch break.
First, you need mortise, not paring chisels. These are Japanese
chisels that I bought from Highland Hardware
they first opened more than 2 decades ago to replace the badly
worn family ones.
Note the flat bevels in the photo; not hollow ground and no
secondary bevel. These are laminated blades designed for
striking, and they come in the exact width of your intended
mortise, ¼, 3/8, and ½ inches.
Also note that the backs are hollow ground to facilitate easy
flattening as you hone them during their life. You can see the
hollow above the edge.
bevels should be touched up on the hone every time you use them;
your stones ready for use should be a permanent fixture on a
corner of your bench. Honing these is easy; just index the flat
bevel on the stone. You also need to hone the back dead flat,
and I also hone the sides lightly on the fine stone to remove
use a set of 4 Arkansas stones all the way to the finest “black”
grade, but you can use what you normally sharpen with. I wiped
the oil off the stone and chisel for clarity; don’t hone them
dry or the stone’s pores will clog.
do a final stropping on the stitched muslin wheel with
Knifemaker’s Green Rouge. Hard felt wheels are the best for
this, but they are expensive.
lay out the mortises on the prepared stock to match my chisel. First, the mortise gage double tines are set to the width of
this half-inch chisel. Then the mortise gage fence is set for
mortise location on the stock, and lines scratched.
Want to have
the mortises dead center? Simple, just run the fence down the
other face of the stock, compare the marks, and adjust the fence
until the marks are identical.
It’s a simple matter to mark your mortise width with try square
and marking knife. I’ll cut a simple blind double mortise and
a pencil to make the lines clear in the photograph. You
need to leave your pencils in the drawer for this and other
joinery marking, as they are insufficiently precise.
Index your mortise chisel plumb in the end knife cut, and strike
with a wood mallet. Do all four ends.