Jack wrote in
:

On 12/22/2015 6:45 PM, Larry wrote:
John McCoy wrote in
:

dpb wrote in
:

On 12/21/2015 2:01 PM, John McCoy wrote: ...

"Strong enough" is probably true in most cases. I
think a tenon which fits the mortise in both directions
is stronger (and if I remember correctly FWW's test a
few years back confirmed that), but it's probably
stronger than it needs to be for most applications.

Something which takes a lot of racking force across a
small joint, like a chair assembly, would probably
benefit from a fully-formed tenon.

I recall the article pretty well; I don't think this
particular point was in the test matrix.

Are we thinking of the same article? FWW has done
two or three tests of that nature - according to the
handy-dandy index, the one I'm thinking of was in
issue 203 (and, of course, when I look at my stack
of magazines, it goes 202 - 204, and 203 is nowhere
to be found).

Anyway, I do recall M&T joints were found to fail by
the tenon breaking, and while I don't recall if they
postulated a mechanism for that failure, I'd worry
that a short tenon would be more prone to break.

John

From the FWW Issue 203...

The test was for diagonal compression (racking force.) All
results in pounds.
Half lap 1603
Bridle 1560
Splined miter 1498
3/8 M&T 1444
3/8 floating M&T 1396
Miter 1374
3/8 wedged M&T 1210
3/8 pinned M&T 1162
5/16 M&T 988
Beadlock 836
Dowelmax 759
1/4 M&T 717
Pocket screw 698
Domino 597
Biscuit 545
Butt 473
Cope & stick 313
Stub tenon 200

There ya go...

That's interesting stuff, but, I have some serious
questions on some of it, most of it the more I look at it.
For example, a floating M&T is way, way stonger than a
Domino? I thought a domino WAS a floating M&T??? A
splined miter is really strong, I don't think so. A butt
joint is not even really a joint, imo. A butt joint needs
dowels, pocket screws or something to make it a joint.
Gluing two pieces of wood together with end grain doesn't
work, so what on earth were they talking about? A 3/8 M&T
is a stub tenon, and pretty much a cope and stick, for the
most part, so again, it's not clear to me what they are
doing. A miter joint is stronger than a domino? Really? A
miter joint is the weakest joint I know of, other than a
butt joint.

Can't wait to see what Leon thinks of this list,
particularly the domino joint being near the bottom of the
list. Hogwash I say:-) Who made this list, Scott
Phillips?


Just to be clear, the 3/8 M&T is the tenon thickness, not
depth. The stub tenon looked to be about 3/8 deep from the
picture.

The 2 I have a problem with are the miter and butt. Both would
be at the very bottom if I were guessing.

Just reposting the results... Don't shoot the messenger.