When it comes to M&T joints, I suck. They look like crap and fit like, well
they fit poorly. I just don't do them for that reason.
My life has changed. Under the tree was a Delta mortising machine and Delta
tennoning jig. Finally put them together today and made a near perfect
joint the first time out. It brings new life into woodworking as now I can
finally make projects with M&T joints with no fear. I hope to start on one
this weekend. The design is in my head already, just have to put it on
paper and then start cutting. It is just going to be a simple magazine rack
with a poor rip off of mission style.
Sure wish I had this combo when I built the Tudor bench and the 50 m & t
On 28 Dec 2003 19:17:08 -0800, firstname.lastname@example.org (Tom) scribbled:
Yes, 2 *identical* blades with spacers.
For spacers, I use 1/2" polycarbonate (lexan), 1/8" acrylic
(plexiglas), other thin plastic scraps, cardboard from cereal boxes,
paper, shims that came with my dado set. Anything else that's flat and
that can be cut with a hole saw would work. I cut the spacers with a
2-1/2" hole saw, and then drill a 5/8" hole for the arbour.
You will need to make zero-clearance inserts, but then you have a few,
doncha? You should be using them in any case if you're cutting tenons.
The procedure is to first cut the mortises. They don't have to be
perfectly centred, but they do have to be a consistent distance from
one side of the piece of wood you are mortising. Then you set up the
blades and spacers so that the thickness of the tenon is exactly the
same as the width of the mortise. A few test cuts and adding and
removing shims are probably needed here, although I did get lucky
Then you adjust your tenoning jig, again with a few test cuts, until,
when the tenon is inserted, the face of the tenoned board is exactly
flush with the mortised board. Bingo! Just be careful to always put
the same face against the tenoning jig.
Replace "no" with "yk" for real email address
Or just use the same reference face on the tenon jig at all times.
Have tenon stock milled. Yes, it is preferred to mill it all at the
same time to get it to the same size, but things happens in life.
This process described below is for centered tenons. If an
off centred (centered for some viewers) tenon is required, then
make the shoulder cuts on one face first, then adjust saw height
to make the other face shoulder cut before starting the face cutting
operation. Additionally, this is but one way of achieving tenons
with the same thickness.
Cut the two shoulder cuts on the face sides of the tenon stock.
If the stock has some variance in its thickness of 1/16" or
less, one shoulder cut will be a little shallower, and once the
face cuts have been made, a little clean up with a sharp chisel
is in order if one does not raise the saw height to the full tenon
length. If cutting shoulders on the edge sides, adjust saw
height, and cut edge shoulders.
Cut the first face of tenon.
Adjust tenon jig to cut other face of tenon with the same face
against the jig that was used for the initial face cut. In other
words, offset the jig by the thickness of the saw kerf and the
desired tenon thickness. The caveat here is if the jig will allow
for it due to the thickness of the tenon stock, or the design or
capacity of the tenon jig. The delta jig mention in the OP does
work in this manner for 3/4" stock, or at least the delta tenon
jig in my shop does.
Cut other face of the tenon.
Result -- same thickness of tenon, even though there might be a
slight difference in the thickness of the tenon stock. This method is a
bit slower than the two blade method. Not all saws can handle two
blades and a spacer, and some woodworkers either dont have two blades
or the inclination to use their saws in this manner.
For the delta jig, a spacer the thickness of the base plate is used during
the above process.
*Cut tenon face furthest away from the reference face (usually marked
somehow to signify that it is the good face) on all the tenon stock.
*Offset the jig. This usually means the tenon stock is now resting on the
table saw top instead of the jig base plate. Put the spacer on the table
saw top beside the jig, secure the tenon stock into the jig, remove spacer
to a safe place to the side. Instead of using this spacer, one could adjust
the saw height.
To speed things up even more, often the jig and table saw are only set for
the initial far face cut. For the second face cut, two spacers are used: the
temporary one used to set the height of the tenon stock, and a second
spacer (as thick as the saw kerf and tenon thickness) is sandwiched
between the stock and the jig face.
*Cut the other face of the tenon stock.
Think thrice, measure twice and cut once.
Sanding is like paying taxes ... everyone has to do it, but it is
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