I've never heard anyone suggesting it needs to be considered. Since
most aprons are 3 or 4 inches and the tenon is something less than
that, the amount of expansion shouldn't be a problem.
Additionally, some folks offset the tenon from the the top creating a
bigger shoulder on the upper portion to leave some strength in the
upper portion of the leg vs having a mortise all the way up near the
top.
I've never had a table break and I typically try to keep keep them
pretty tight. I'd also like to hear if someone has learned or heard
differently.
BW
foster239 wrote:
> What is the general rule for fitting the height of the tenon on a table
> apron? Since this is a cross grain situation how much room is usually
> left at the top and bottom of the tenon to account for expansion and
> contraction?
Nice, now I understand why people do those multiple tenons and great
advice on the glue up.
Jesse R Strawbridge wrote:
> foster239 wrote:
> > What is the general rule for fitting the height of the tenon on a table
> > apron? Since this is a cross grain situation how much room is usually
> > left at the top and bottom of the tenon to account for expansion and
> > contraction?
> >
> On large tendons, leave a little room at the bottom of the mortise for
> expansion and glue only the top third. The size of the gap depends on
> the wood and its expansion rate. Tendons of 4 inches or less probably
> don't need to account for the expansion.
>
> Alternately, divide the tendon into multiple smaller ones with matching
> mortises.
>
> Jess.S
foster239 wrote:
> What is the general rule for fitting the height of the tenon on a table
> apron? Since this is a cross grain situation how much room is usually
> left at the top and bottom of the tenon to account for expansion and
> contraction?
>
On large tendons, leave a little room at the bottom of the mortise for
expansion and glue only the top third. The size of the gap depends on
the wood and its expansion rate. Tendons of 4 inches or less probably
don't need to account for the expansion.
Alternately, divide the tendon into multiple smaller ones with matching
mortises.
Jess.S
"SonomaProducts.com" <[email protected]> wrote in message
news:[email protected]...
> I've never heard anyone suggesting it needs to be considered. Since
> most aprons are 3 or 4 inches and the tenon is something less than
> that, the amount of expansion shouldn't be a problem.
Agreed. Starting with a ballpark worst-case scenario of 1/4" per foot
seasonal movement... that's a 1/16" inch summer expansion on a 3" tennon
*if* you assemble the table in the bone-dry dead of winter.
Good luck even assembling (dry fit and disassemble) that M&T joint
(assuming at least a 1" depth) with less than 1/16" of top and bottom
wiggle.
-Steve