Hi: I just finished building a slide assembly for my Shopsmith that allows
me to easily make "loose" mortises. One question remains...

Should the "loose" tenons be the same material, or would a more stable
material such as tempered fiberboard be the prudent choice. The fiberboard
is precisely 1/4", does not swell and is very strong. Not to mention, easy
to "store" in the shop.

Does anyone have first hand knowledge with loose mortise and tenon
construction.

John Eppley

No experience with loose tenons, but I'm thinking the tempered
fiberboard wouldn't take glue very well.

RayV wrote:
No experience with loose tenons, but I'm thinking the tempered
fiberboard wouldn't take glue very well.


Even if it did take glue well, with no grain to span the joint, I doubt
you'd ever gain much strength. If I were going to use anything but
wood for the tenons. it'd probably be scuffed-up lexan or sandblasted
aluminum, though I don't ever see myself trying that. Actually, I have
a Beadlock unit for just such situations and it performs very well.

I am sure it takes glue very well. I built a shelving unit that spent many
years in unheated cellars, garages and storage sheds. Did I mention I built
the unit in 1961 ??

John

John Eppley wrote:

Should the "loose" tenons be the same material, or would a more stable
material such as tempered fiberboard be the prudent choice. The fiberboard
is precisely 1/4", does not swell and is very strong. Not to mention, easy
to "store" in the shop.

Try a strength test between the fiberboard and some other
candidates...sugar maple, ash, white oak, etc.

Chris

John,

I'm no expert, but can relate my experience using loose tenons on a
large rolling wood rack. It was made of milled 2x4 and 2x6 rails with
28 loose tenon joints. I did the traditional approach of making them
close to right, then used a hand plane to fine tune the thickness of
each tenon so that each had an ever-so-slight drag in a piston fit that
could be moved with hand pressure. After applying glue, I had to
assemble quickly because the wood swelled and "locked" in place. My
impression was that I had some tolerance in fit because the swelling
wood "self adjusted" to a tight fit. the precise thickness, no swell
character of the fiber board may work against you because it requires
such a precise fit to be effective in the joint - too tight and there's
no room for glue - too loose and the glue won't fill the gap.

Bob