Richard Heidel wrote:
>
> I've seen many ways to cut mortises and tenons. Is there a rule of thumb
> about the size? I usually figure on about half the stock thickness for the
> thickness of the tenon, but what about length?
Depends on what the joint is intended to do.
1 - alignment only of two joined parts, not intended to keep the parts
from
pulling apart, then a 1/4 inch stubby would work
2 - alignment AND keeping two parallel parts from moving apart - like
shelves
then 1/2" and glue would work
3 - #2 AND expanding and contracting WITH the parts the tenon goes
into -
through tenon, with a wedge or two for insurance
4 - #3 AND knock down/take apart/tighten - like a bench's stretchers -
then
long through tenon with mortise in the tenon for a big wedge
Also depends on what it might interfere with - a table apron to top of
legs
for example. You don't two want tenons to a) bump into each other or
leave
so little material on the mortised part so as to have no strength.
As for the width of the tenon - again it depends on what the joint is
intended to do. You've got 6 types of motion to deal with - movement
on the x-axis, movement on the y-axis and movement on the z-axis along
with rotation about each of the three axis. The size of the shoulders
mainly deals with rotation around one or more axis.
Rather than go on just check out
www.wood-workers.com/users/charlieb/M&TPrimer0.html
And while your there, if you haven't tried handcut dovetails, have a
look
at
www.wood-workers.com/users/charlieb/DovetailDrawer0.html
Hope this helps.
charlie b
On Tue, 16 Dec 2003 16:21:51 GMT, "Richard Heidel"
<[email protected]> wrote:
>I've seen many ways to cut mortises and tenons. Is there a rule of thumb
>about the size? I usually figure on about half the stock thickness for the
>thickness of the tenon, but what about length?
>
One third to one-half is about right, but consider matching the width
of your chisel or router bit. A deeper tenon will provide more
gluing surface, and therefore a stronger joint. A short tenon is
called a "stub tenon," and can be perfectly fine for applications
where strength is not a big concern.
To me the "rule of thumb" for "thickness" has generally been 1/3 the
thickness of the stock. IOW, a 1/4" thick tenon in 3/4" stock.
Length, for a non-through tenon, is generally is 1/16th - 3/16th less than
the depth of the mortise to allow for the glue.
--
www.e-woodshop.net
Last update: 9/21/03
"Richard Heidel" wrote in message
> I've seen many ways to cut mortises and tenons. Is there a rule of thumb
> about the size? I usually figure on about half the stock thickness for the
> thickness of the tenon, but what about length?
>
>
I hesitate to read any meaning into what is said ... therein lies the
beginning of many a flame fest.
Traditionally the depth of a mortise is about 3/4 the width of the leg or
stile.
Depends on a number of things, the size of the workpiece in which the
mortise is being cut, the size of your chisel/tools/bit, the stroke of your
mortise machine, whether you are using joinery like mitered tenons, etc.
On a 1 3/4 to 2" " table leg, I generally make my mortises about 1" deep ...
maybe a little deeper for thicker table legs, or when I want to miter the
ends of the opposing tenons.
--
www.e-woodshop.net
Last update: 9/21/03
"Juergen Hannappel" <[email protected]> wrote in message
news:[email protected]...
> "Swingman" <[email protected]> writes:
>
> > To me the "rule of thumb" for "thickness" has generally been 1/3 the
> > thickness of the stock. IOW, a 1/4" thick tenon in 3/4" stock.
> >
> > Length, for a non-through tenon, is generally is 1/16th - 3/16th less
than
> > the depth of the mortise to allow for the glue.
>
> To extend the original question to what was probably really meant: How
> deep to meke the mortise (if non-through)?
>
> --
> Dr. Juergen Hannappel http://lisa2.physik.uni-bonn.de/~hannappe
> mailto:[email protected] Phone: +49 228 73 2447 FAX ... 7869
> Physikalisches Institut der Uni Bonn Nussallee 12, D-53115 Bonn, Germany
> CERN: Phone: +412276 76461 Fax: ..77930 Bat. 892-R-A13 CH-1211 Geneve 23
Swingman wrote...
> I hesitate to read any meaning into what is said ...
Don't blame you...
> Traditionally the depth of a mortise is about 3/4 the width of the leg or
> stile.
Ah, traditions! (G) I traditionally cut blind mortises between 1/2 and
2/3 the width of a stile or leg, but it really depends more on the
application dimensions, as you subsequently noted.
Also, I saw in your first post that you suggested 1/3 stock for tenon
thickness. When joints with those dimensions do fail in the wood, it is
by tenon fracture, and virtually never by mortise wall failure. (Of
course, the vast majority of m/t failures are glue failures.) This
suggests that a thicker tenon would lead to a theoretically stronger
joint, and so I went to approximately 1/2 stock for tenon width a number
of years ago. I can't say I've really notice any difference -- never had
a tenon failure before switching, either -- but it does seem to be a
sensible change.
I don't intend any of this as a contradiction to your custom, but rather
to point out that mortise-and-tenon joinery is tolerant of a fairly wide
variance in component dimensions.
Jim
"Swingman" <[email protected]> writes:
> To me the "rule of thumb" for "thickness" has generally been 1/3 the
> thickness of the stock. IOW, a 1/4" thick tenon in 3/4" stock.
>
> Length, for a non-through tenon, is generally is 1/16th - 3/16th less than
> the depth of the mortise to allow for the glue.
To extend the original question to what was probably really meant: How
deep to meke the mortise (if non-through)?
--
Dr. Juergen Hannappel http://lisa2.physik.uni-bonn.de/~hannappe
mailto:[email protected] Phone: +49 228 73 2447 FAX ... 7869
Physikalisches Institut der Uni Bonn Nussallee 12, D-53115 Bonn, Germany
CERN: Phone: +412276 76461 Fax: ..77930 Bat. 892-R-A13 CH-1211 Geneve 23