For me, I try to standardize as much as possible, to minize setups, and
math errors. Sometimes aesthetic concerns override this system, but I can
generally make these work.
Also, always measure, or register you work from the same face of your stock,
That way, if you are a little off, it will always be consistent.
When I design, I sometimes have both "structural" and "non-structural"
tennons. If I have a frame with slats in the middle, I generally consider
the slats to be non-structual (they do add significat ridgidity but the main
work is done at the corners of the pannel.
1/2" deep for nonstructural, I like 1-1/4 for structural.
There's a couple of considerations, pretty much in this order:
1. Tennon should be inset from sides of the slat so as to hide the edges of
2. Tennon should not me much thicker than 1/3 of the thickness of the stock
into which it is inserted (not to be confused with the thickness of the
3. All dimensions are in even 1/8th's to mitigate brain cramps.
4. Adequately beefy, bigger is generally better, 1/4 is fine for a cabinet
door. 3/8 is prefeerable for a carcass.
5. All tennons in a project, if possible, should be the same thickness to
Just as a convention to keep things simple:
I put a 1/4" shoulder on all tennons (tennon is 1/2" less wide then tennon
The corresponding mortise is at the end of a board, then shoulder is 3/4"
The tennon stock is > 3" I'll inset the shoulders 3/4" and only glue the
center of the tennon if it's really big.
Yes, I'm suggesting making the mortise the size of the whole slat. It will
require the same level of accuracy as cutting a tenon to fit in the mortise,
but you will save the time of actually cutting tenons. If one of the
mortises ends up slightly large, and a gap is seen, simply cut the slat a
few thous larger. One of my first projects was a mission style buffet that
had slats on the sides of the case. I cut the mortises with an attachment
for the drill press I had at the time, cleaned them up with a chisel, then
cut the slats so they fit snugly into the mortises. It worked well, and I'd
do it again. If the slats are cut tightly enough, the edges of the mortise
are very close to invisible. You can always try this method on scrap pieces
to determine if it'll work for you. --dave
What size mortising bit/chisel do you have? Most folks (the smart ones) let
their tools determine the mortise and tenon widths.
Otherwise, make the tenons 1/4". You will have an 1/8" shoulder, but that is
fine for slats and it makes them easy to cut on a table saw using a dado
set. Use a 1/4" mortise bit/chisel to cut the mortises.
NOTE: If you use the optional "slat" solution that I mentioned to you in my
last post, just use the slat itself as the "tenon", and a groove, running
the length of the rails as the "mortise", then fill in between your regular
Don't make a mortise for the slats. Using your router table with a straight
bit, cut a 1/2"x1/2" slot in the rails. Fill the gaps with 1/2"x1/2"x 1"
Simple and does not require accurate mortising.
You would only glue the blocks. The slats would float.
I posted an illustration in A.B.P.W
Make the blocks out of the same wood as the rails. It will be very hard to
tell they are not real mortises.
I don't know. I've been doing this for years now and I still couldn't
give you a simple answer to this - it's just not an easily answered
question. Even just for cabinetry, without getting into green
First of all, they should fit your mortices. To me this means making
them a size that matches a chisel in my morticing machine. It also means
cutting them afterwards, to exactly fit the mortices. I bandsaw my
tenons, which is easily and accurately adjustable, to fit mortices I
have much less control over.
Secondly they should be the full width of the timber. Use two shoulders,
not four. Run this long width along the grain of the mortice, not across
it. Sometimes haunching is good too. Read Tage Frid's book.
For rough width on the short axis, somewhere between 1/3rd and 1/2th of
the timber thickness, usually tending towards the thicker measurement..
if the slats are big wide cross-grain things, then start to worry about
moisture movement. Breadboard-end techniques start to make sense, not
Cats have nine lives, which is why they rarely post to Usenet.
Hmmm. I always use four because I always make my mortise a little longer
then the tennon so that I can wiggle a joint back apart after a dry-fit. The
extra two shoulders cover the intentional < 1/8" gap.
How do you disasseble a dry fit with no wiggle?
Mallet. I use the ugly black rubber one for this. Scrap of pine against
the work, tenon piece held in the bench vise. Whack (gently but
firmly) the mortice piece on alternate sides of the tenon piece. If I've
done a sloppy job of making either piece, I clamp the mortice piece in the
bench vise and just haul on the tenon piece bare-handed.
"Keep your ass behind you"
wreck20051219 at spambob.net
On Fri, 10 Feb 2006 21:53:23 -0500, "C&S"
I don't see why wiggle-room depends on how many shoulders you laid the
tenon out for ?
If you're concerned about visible gaps, then that's carelessness, not
just wiggle. You'd also be bringing in the problem of cutting the
shoulders neatly enough that you don't get any unevenness where the four
shoulders meet (and thus a gap at the end of the tenoned member).
Something I forgot to mention was that the length of tenons should be at
least as long as their minimum thickness. Unless they're shorter than
this, in which case it's a "stub tenon" and don't expect it to be so
strong. Pegged tenons (with a drawnail through them) need to be even
longer, so that the shortest length of unsupported short-grain timber is
as long as the thickness and there isn't a risk of it breaking out, The
thinnest part of long-grain timber (side of the mortice, where the nail
is going) can be a bit thinner than this, depending on species.
Incidentally, to disassemble a Wiggle you find the Australian parent of
multiple small children, then give them a Wiggle and a big mallet.
They'll do the job for you....
Cats have nine lives, which is why they rarely post to Usenet.
No it's intentional... I have made them tight and have stopped doing so
because it gave me too much greif.
I'm not talking about stub tennons. A recent project is representative of
my typical aproach:
1"x2.5" stock give me tennons 3/8" x 1-1/4" x 1-3/4" or 2-1/4" (end or
middle). I think you would have a tough time pulling apart a frame with a
single interior rail (6 joints) of that depth and no wiggle without the aid
of a reversed cabinet master clamp..
Have you ever had a glue up have a problem, where you say "Oh sh*t I have
to back that out" as you are just pulling the joint together and you realize
something doesnt work (if you're like me it's probably the last time you
neglected to dry-fit something) and you can barely get it apart? I think to
myself, boy is this going to be strong when there is cured glue in there
rather than wet glop.
It's my contention that, if the joint is approriately snug on the thuckness
dimension, the should shoulder of the tennon, in conjuction with the sheer
strength of the glue on both faces of the tennon (4-3/8 square inches of
glue area per joint), is way more than enough to resist racking forces
placed in the frame. (compressive forces, just push the joint together and
simple pulling forces are a bit unusual for a furniture carcass and not
largely effected by tennon width)
Perhaps, it's modern glues that give me comfort ing taking this liberty.
On Sat, 11 Feb 2006 08:48:17 -0500, "C&S"
No - not since I abandoned PU glue! Now I use hide glue for nearly
everything and rarely have trouble. I can abandon a job 20 minutes after
gluing it, pull it all apart by hand and just leave it on the bench in
disgust. Clean up for a later attempt is easy.
Most of my tenons are dry-fitted anyway. These days I'm inclined to a
fairly "rustic" approach, either big timber framing or medieval oak
repro. Although I may well glue this too, it's designed to be dry
assembled and often is held purely by the treeenails.
Resisting racking, IMHE, relies on adequately wide tenons and in getting
some good compression onto the ends of the tenon member. I do this by
pegging my tenons with some draw on the pegs to pull them tight. Gluing
is certainly possible - plenty manage it, but it needs good flat
shoulders and some decent clamping during glue-up.
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