what's the advantage to haunched tenons, other than filling the groove in
the end of stiles in frame/panel joinery? I see a lot of designs, and it
almost seems like the haunch was thrown in arbitrarily.
I'm talking aside from frame/panel applications where you need some way to
fill the groove, like joining table aprons to legs. I've been looking at
a lot of table designs, and a lot (mostly all one guy) use haunched tenons
for the table apron to leg joint, and the haunch seems unnecessary, and
maybe even a liability...
On Thu, 05 Feb 2004 19:26:36 -0500, Mike G wrote:
|I'm talking aside from frame/panel applications where you need some way to
|fill the groove, like joining table aprons to legs. I've been looking at
|a lot of table designs, and a lot (mostly all one guy) use haunched tenons
|for the table apron to leg joint, and the haunch seems unnecessary, and
|maybe even a liability...
It is my understanding (and thus why I'm using them on a table I'm
building) that the haunch gives extra resistance to twisting of a wide
apron, while allowing a narrower tenon. If a wider tenon was used the
glue joint could fail due to wood movement.
But what do I know, I'm a realative novice at this [g].
In addition to wider tenon, it allows the deep part of the mortise to
be kept further from the top of the leg. When the top of mortise is
too close to top of leg you have a situation where that thin piece can
be blown out in the process of fitting and gluing the apron. I like
to have at least 1/2 inch on top and often keep tops of legs long and
then trim to flush with apron after fitting is done but before gluing.
Well then the answer is even easier. For one reason or another all the
joints you have been looking at, "mostly from one guy", is that it's the one
guy's preferred joint.
While I think it is overkill and see no advantage in it for the extra work
to joint an apron to a leg that one guy probably does. Then again, there's
no law against overkill in joints.
My understanding is that traditionally the frame (rails and stiles) for a
panel would have been grooved with a plough plane. A plough plane doesn't
allow for a stopped groove, so the groove goes the distance of the rail or
stile. So you guessed it, the simplest way to fill this groove is a haunched
I believe the point of the haunch, especially in non frame/panel apps,
is to provide extra stability in the form of resistance to racking w/o
having to weaken the mortise by removing too much wood. IOW, you can
get a taller tenon w/o getting the mortise so close to the top as to
risk blowout in fitting/gluing. Consequently haunches are sometimes
used in situations where there may not even be groove needing fill.
: what's the advantage to haunched tenons, other than filling the groove in
: the end of stiles in frame/panel joinery? I see a lot of designs, and it
: almost seems like the haunch was thrown in arbitrarily.
Haunched tenons ('thrown in' for centuries) are used at the corners of
The haunch is the wood between the end of the mortise and the end of the
If there was no haunch, the end of the stile (of a through jointed frame)
would consist of a slot, the joint becoming in effect a bridle joint.
Such joints will have greater gluing area, but are more difficult to cramp
up at gluing-up time. To keep the shoulders close, cramps are needed along
both the stiles and rails and a 'g' cramp (or similar) is needed to prevent
the flanks of the slot from spreading.
Hence, like other features in joints, ease of assembly is a fundamental
Jeff Gorman, West Yorkshire, UK
Email address is username@ISP
username is amgron
ISP is clara.co.uk
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