I have been doing woodworking for a few years now but I am about to do my
first serious mortise and tenon joints on a set of three nesting tables. I
have watched Norm do these a lot but I don't have a dedicated mortiser. I
will use either a router and jig to cut the mortises or a drill and chisel.
I am wondering about your experience in doing accurate marking of the wood
where the mortise is to be cut. I have seen various mortise marking gauges.
Have you used these? Do you need these or is your hand and measuring ability
proven steady enough to draw the lines some other way?
This group has invariably been helpful to me when I ask questions so I am
looking forward to some help before this next step in improving my
The mortise gage is recommended. You set the gage to match the width of the
chisel. You set the mortise back from the edge and mark both the tenons and
the mortises with the same setting so they match. I mark the ends of the
mortises with a utility knife.
I have sometimes marked just one edge of the mortise with a marking gage,
mark the ends with a knife and just set the chisel against the one line. It
works because the tenon width is the same as the chisel width. I still use
the mortise gage to mark the tenons.
Woodwork magazine has had good information about this subject. You can
download a pdf copy of the magazine if you care to.
Frank Klausz has a good video on mortise and tenon joinery. He shows using
the chisel, router and the mortiser.
Thanks. I will hunt around for the information after work tomorrow. I see
that Frank Klausz has a website. Is that where I should look for the video?
I have seen two kinds of mortise gauges. One is a block of wood (I always
see them made out of Rosewood) and other is a sharp wheel with a stop to set
the distance. What kind do you use?
I have both :-)
I prefer the wheel for most marking, but use the mortise gage when marking
Actually I have two of each. You can set one for one measurement and the
other for another measurement and not lose a set-up in case of a screw-up in
cutting or chopping.
I am a machine guy myself. I would cut the mortise with a router and a
jig. I like trhe simple one with two fences to sandwich the piece
being mortised. Square up the mortise ends with a chisel. Cut the
tenons on a router table with a little sled and backer for clean cuts.
Cut the tenon wide and sneak up on the fit with a shoulder plane. Nice
reason to buy a nice small hand tool. http://www.woodcraft.com/family.aspx?familyid=20370
As one person mentioned use a knife to cut the edges of the mortise
where you will chiesl it. Also, if you will drill and chisel, then lay
out the mortise with a knife to create clean edges, then dril and then
chisel to the knife cut line.
jig. I like trhe simple one with two fences to sandwich the piece
I'm with you.
Router and a simple jig does a nice job.
I don't bother cleaning up the corners of the mortice, just leave them
round since the strenght of the joint is achieved by the shear loading
of the glue faces.
Knock the corners of the tenons off with a flat bastard file and
As suggested, sneak up on the tenon thickness since it has a major
impact on the overall strength of the joint.
Just my $0.02.
The scribed line is what's important. It creates a groove to click
chisel into for the last paring cut to make a dead straight line. A 4
6" combination square and a knife works just as well, though requires
a steadier hand, no big deal, since if you slip, you're marring the
that gets chopped out anyway.
That said, the Stanley 95 butt gage works even better as a mortise
gage. Double beams, both narrow, easy to see what you're doing.
I've used a combo square with a locked blade, steel ruler, LV marking
gauge, and a Titemark to mark mortises.
When cutting them with a machine, router, DP, or mortiser, I find the
combo square or ruler, and a sharp pencil, plenty accurate. With the
machines, you'll have the benefit of fences or stops. If you reference
the same faces for each set of mortises, the opposite ends of the same
tenoned board, off of the fences or stops, it won't matter much if
you're 1/32" or so off center where the tenoned board is inset from the
mortised boards (ex:// typical aprons & legs). Both ends will be
identical, so the interface will remain square.
If the tenoned board will be flush with the mortised board (ex:// many
doors), you need to try a bit harder, but 1/64" can easily be cleaned up
with a smooth plane or sanding block.
For handcut stuff, I like the two round marking (cutting) gauges, as I
like the way the scored lines interface with the chisel tip for the
final paring cuts.
I say have at with some scrap of the same species you'll be working.
BTW, if you're machining the mortises, cut the tenons last. This will
allow you to cut them a hair oversize and trim them to fit. Trimming
can be accomplished with a shoulder plane, rabbet block plane, block
plane and paring chisel, rasp, or even a hard sanding block. As you
trim the tenons, make pencil lines on each face to ensure you're
removing material evenly, and slowly sneak up on the fit. Speed will
come in time. If you accidentally make a tenon too thin, glue a strip
of veneer or scrap block on (mind the grain), recut if necessary, and
If you rout the mortises, it will have round ends. I prefer the speed
of knocking the corners off the tenons with a rasp or paring chisel,
others chop out the corner of the mortise. I don't see a difference in
the finished product, but the choice is up to the craftsperson. <G>
Take your time and practice lots, as this is probably the most important
joint to learn and you'll get lots of payback from the practice.
I have a hollow chisel mortiser but still prefer to use a router.
Simple jig to set the mortise location on your piece. Flat board with
a fence added and a couple of limit stops (can be adjustable) to set
the feed length of the router. Work piece clamped in the jig, and
clamped to the table. Usually takes me about a half hour to make a
jig, and I tend to repeat the leg size so use them over. I have
three thicknesses of legs covered.
I just rough locate with broad pencil then rout a sample and calibrate
from that. The first mortice is never on the money so why waste time
I know the dimensionality of the tenon. I measure my first sample
mortice and calculate how much wider/narrower, longer/shorter,
centerline shift etc is necessary. Make the changes with the edge
guides and stops. The second sample, minutes later, is usually
correct. Much less time calibrating than going nutz with the layout.
If using power tools the marking is less critical because you have
fixed-size jigs/templates/bits/fences. For hand-cut (including
drill/chisel techniques) the marking is more important because it
provides a registration point for the chisel.
For the ideal joint tightness you want the joint to go together dry by
hand without requiring a hammer, but you should be able to pick it up by
the tenon piece and not have the mortise piece fall off.
I would study on mortise making using a router and many
different jigs that are around.
This eliminates one challenge of what is the size
of the mortise.
It will always be the very same for every single
mortise and you just have to cut your tenons to fit.
I think every single magazine has come up with at
least one decent mortising jig for routers.
Cut your tenons using a table saw jig or use
your router table, which ever you are most
You notice I didn't mention a marking gauge ???
You don't need a gauge for accurate mortise
work in my opinion.
Dick Snyder wrote:
Does anyone use floating tenons? I saw those in a book on
cabinetmaking and that certainly seems the way to go best for the
machine guys here. Just mortise both pieces then cut the tenons from
pre-rounded (1/4" roundover I think) stock cut to size.
I don't think you were being derided. The Domino is a great new tool
from Festool that is like a biscuit joiner but cuts mortises for
floating tennons and they sell you the tennons pre-made just like you
buy biscuits. Thing is it is like $500 or more, can't recall exactly.
The Multi-router is (to some of use) the holy grail of router tools.
It holds a router and has a movable part holding table and a template
following system for cutting mortises, tennons, dovetails, etc. A few
thousand and about $3k pnce you get all setup with all the
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