I've already fielded some advice about alternatives to square (through)
mortises. But for now - at least until I find out what a pain they are -
I intend to try to make some.
From what I can glean so far, the chief advantage of mortise chisels
seems to be their thickness; they are nice and strong for lever action.
But I won't be chiseling out the whole mortise, only the corners. I'm
wondering if mortise chisels have any advantage over standard bevel edge
chisels for that task.
If so, would you get a chisel the full width of the mortise? Or perhaps
one size narrower?
One more thing: I find myself wondering if it's not easier to get a
straight, square edge if I start out with an oval mortise that is
slightly less long than the finished mortise will be. Otherwise I would
need to somehow chisel an edge that's exactly tangent to the
semicircular edge of the routed mortise. Any thoughts?
Consider also that there are also square cut chisels. They cut both
sides of the corner. Swingman uses/has one that looks like a
conventional chisel and I have one that indexes.
I would advise establishing the corners with the chisel first and then
using the router to cut the mortise. Then clean up with the chisel.
Mine is more intended to clean up shallow hinge mortises.
I have gotten conflicting advice on those, even in this thread. My
sharpening skills are in their infancy, but I have had a *minor* amount
of success using one of those roller guides for regular chisels and
plane irons. Would a person who can scarcely sharpen a regular chisel be
able to use a corner chisel efficiently?
I did a little experimentation with regular bevel-edge chisels. They
work OK, actually. With a little practice I think I could make neat
edges. But I decided to buy a corner chisel and see if that seems more
efficient. It's a Narex, a brand that seems to get good reviews, despite
being reasonably priced. We'll see how it works. It should arrive today.
On Wednesday, April 29, 2015 at 2:15:59 PM UTC-7, Greg Guarino wrote:
[about square through mortises]
If the bevel edge chisel can take a mallet blow on the handle, I'd say it's good
enough for squaring a mainly-cut mortise. It's my understanding
that mortise chisels are most useful for mortises that match the chisel
width, because they guide in the mortise; bevel chisels are more
for freehand-ish cutting, which means you can use any size that
fits, but you have to guide the cuts with care.
Corner chisels are scary: how do I trust an edge, if I can't sharpen it?
And, how do I get a good cut in both directions at once? One foresees
a possibly protracted and unpleasant learning experience.
No - it would be a pain to use a mortise chisel to square up the
end of the mortise. If you really want a special tool, the thing
you're looking for is a corner chisel. A firmer chisel would be
the ideal thing, but a regular bevel edge chisel is fine.
You want a chisel the same width as the mortise (in fact, if
you were doing this handtool style, the width of the chisel
defines the width of the mortise, and you cut your tenons to
match the chisel).
There's two things to consider here. One is the mechanical
locating of the tenon by the end of the mortise. For that
you want to cut the end square to the sides, but if there's
a little divot where the router cut goes beyond, it doesn't
matter - the tenon will be located by the corners.
The other is the cosmetic. For a normal blind mortise with
a shouldered tenon, you don't care what the ends of the
mortise look like, because they're hidden. But in your
case as I recall you have thru mortises, so the ends are
exposed. In this case I think I would stop the router
just a hair shy, and use the chisel to cut to the layout
Interesting. Why is that?
If you really want a special tool, the thing
OK. I just looked up "Firmer Chisel". I see they have a rectangular
cross-section. Can you help me grasp why that would be better for this use?
Incidentally, I made a quick sloppy first attempt using bevel-edge
chisels. One thing I noticed right away was that when I make the cut
parallel to the grain, I have to be very gentle and not drive the chisel
in very far or else it tends to split the wood. I'm thinking that -
besides going a little at a time - I'll probably be better off making
the "perpendicular-to-the-grain" cut first, then removing that small
chip with the parallel-to-the-grain cut. And repeat... and repeat ...
I'm guessing now that this is why you recommend a firmer chisel. Once
you get a little way in, the edges of the chisel will tend to guide it.
That's what I was thinking too. Too difficult to get the chisel exactly
perfect at the edge of the semicircle, I would think.
I've always understood, for cleaning up mortises, and other fine tuned cuts
, one uses a paring chisel. They are supposed to be kept razor sharp, so
as to use your muscle/hand pushing to do the cutting, not by striking with
a mallet. Roy Underwood uses paring chisels, for these kinds of cuts and
clean-ups, and often notes not to use a mallet. They should be sharp enou
gh to cut with hand-pressure force.
I have several paring chisels and use them fairly often. From experience,
for these kinds of cuts, a paring chisel can't be beat.
Check Ebay for Sheffield, Addis, Sorby, or Marples paring chisels and compa
re pricing against other purchasing options. *I like old tools. Some year
s ago, I bought 1/4", 3/8", 1/2" & 1" original Robert Sorby's for about $50
A mortise chisel is heavy and unweildy compared to a bench
chisel, and gives you no advantage in cutting the little
wedge out of the corner.
Exactly. That said, I just use a bevel edge chisel when I
need to clean up the end of a mortise...I think I have a
couple of firmer chisels somewhere, but it's easier to just
grab one of the set that I usually use than to go look for
Working from memory, the answers to my question include:
Use a corner chisel
Corner chisels are too hard to sharpen
Use a regular bevel-edge chisel
Use a firmer chisel (had to look that one up)
Use a paring chisel, no mallet
Use a knife
Change the design
"Fake" the through tenon.
... which is what I've come to expect. I could complain that my range of
options - rather than being winnowed down - only *expands* when I ask a
question here, but that's part of the fun, and how I learn. I know I'll
need to do my own blundering about no matter what answers I get.
So keep it up. Does anyone recommend an electric carving knife? An
dental drill? A laser?
I am still very interested in anyone's personal experience with a corner
chisel, specifically whether a novice can keep one adequately sharp.
It could be that you're overcomplicating the question. Any
of the above will work just fine. Pick one and try it.
Experience will guide you towards the optimal solution, in time.
It's not much more complicated than sharpening any edged tool, and
much simpler than sharpening a gouge. Keep the back
flat and touch up the bevel with a slipstone or a popsicle stick
with self-adhesive sandpaper. Use a file if the edge is significantly
Personally, when I chop the mortise by hand, I use a mortise
chisel. When I use the mortising attachement on the drill
press or the GI mortiser, I clean up the flats with a sharp
paring chisel, no mallet. I've never needed to clean up the
ends of a mortise, even when using the horizontal mortiser
where leaving a half-round gap at the end of the mortise if
the tenon isn't rounded has no effect on structural integrity,
indeed it leaves a bit of room for excess glue.
FWIW, I find the corner chisel more useful with shallow mortises,
like those for hinges (for which the self-registering spring-loaded
cleanup chisel is perfect).
sharpening should be considered a skill learneed by novice/apprentice
it can be a challenge but it's a skill that's real good to be had
i cringe when i see videos and the sparks are flying while someone
"sharpens" their $200+ bowl gouge
Sharpening small bevels: Get a small diamond file, or two. One or two flat files and one or two flat, yet, triangular files. Any small bevel can be easily and quickly honed - corner chisels, auger bits, other small applications.
I have a few small flat-triangular (clock repairman's) diamond files that I use for sharpening auger bits. Very handy, compared to other small files!
The problem with sharpening small bevels is not the sharpening tool, it's my eyeballs (focusing!), despite wearing reading glasses.
Try them all - try a scroll saw. I would be very interested in seeing
pictures of your first attempts, no matter which method you use.
To me, the trick is to use a high quality tool and not let it get dull
past the point where it takes more than a Hard Arkansas Stone to put
the edge back on it. An even better trick is to not have to use them
Can a novice keep one sharp? Sure, don't use it. Can a novice put the
edge back on a dull one? Possibly/probably/maybe - try and see. Can
a novice even use one effectively? Again, you won't know until you
I could be wrong but I don't believe anyone has mentioned a trained rodent.
Mouse, rat, squirrel...depends upon the size of the mortice. The downside
is that the critter has to be trained to gnaw on command. Upside is that
the critter WANTS to gnaw to keep its tooth growth in line.
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