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275767 Richard Wilson <yorkshireman@y...> 2022‑06‑20 Re: gluing tenons
An intriguing discussion about that old and favourite joint, the Mortice and
Tenon.  Anything starting ' I am looking through some old ww magazines,’  gets
my vote.

Snippage throughout

The proposition…  Don stated
>>  In it, he describes tenon glue-up for stub tenons with foxtail wedges as
follows: "... enter the wedges and apply a good exterior glue to the   half of
the tenon nearest the shoulder. Then cramp up. It is bad  practice to apply glue
to mortises, for it is important only half of the  tenon is glued." He doesn't
explain why.
>>    Comments?
>>    Does anyone follow this practice?

and Pete says..
> On 2022-06-19 11:18 a.m., Pete Bergstrom wrote:
>> While it's not a storm door, I just did a glue-up last weekend of a couple of
small drawer enclosures that used dados to hold the drawer separator boards, and
I only glued one end of each joint (i.e., on the visible face; this left the
other end of the joint to float a bit in the provided space.

And Don suggests...
> On 19 Jun 2022, at 23:09, Don Schwartz  wrote:
> That makes a lot of sense in drawer construction where you have a long divider
cross-grain to a the cabinet depth.

It seems to me that there is a lot of slop in the original statement.  There is
no context. No dimensions.  Does the author include ALL M&T joints in his
statement, or only stub tenons, or only fox-wedged tenons. Is he applying glue
for its holding power, or for its caulking properties?
 However, the concept is an interesting one, and one I do not recall seeing in
print before.

Dimensions is clearly important.  You don’t have much shrinkage in the mortice
material if the tenon is a bare half inch in length.  You have appreciable
shrinkage if it is 4 inches, or more.  But then, if you are using a tenon 4
inches long, you would surely be looking at pegging the joint, and in terms of
the strength of joint you no longer rely on glue.  Indeed, most timber framing
joints rely on mechanical strength, and good design, to place the stresses where
we want them.
Back to the item - It is fox wedged, so its mechanical strength has been
enhanced.  It will not withdraw from the joint.  So why glue?  I suggest that it
is to weatherseal the joint, given its likely exposure to driving rain and so
forth.  Joint strength has been assured by the wedges, and to prevent water
ingress to the joint, glue is used to seal it.  In that case, then of course you
would not want the jointline to suffer compromise by any wood movement.

The question of a divider is almost separate.  Many dividers are dry.  I have
some fine examples of box interiors with dividers which slide in and out of
their positions.  This may be very desirable to aid cleaning out, or it may not
if the divider is substantial, and contributing strength. But then, A divider
would normally have its grain running in line with the drawer body, so a full
glue surface shouldn’t compromise the joint when the drawer side and divider are
vertical, and similar timber (in expansion terms)

All of which leads me to say
‘I haven’t used this sugegstion, and I’m not sure I would.  But because of it
I’ll surely think a bit harder when I next have a m&t joint running cross grain.

Richard Wilson
Yorkshireman Galoot 
in Northumberland

Yorkshireman Galoot
in the most northerly county, farther north even than Yorkshire
IT #300

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