Ran a test with #10 biscuits on a right angle butt joint. End grain to long
grain. Two biscuits in the joint. 24 hours later, pulled the joint apart,
took less force then I expected. The biscuits pulled apart, some left in
So my question is, does anyone make solid wood biscuits? Google didn't seem
to have anything.
Thanks, by the way, there is much info to be gathered here. Thanks for that
My questions are:
a) What kind of biscuits are you using, anyway? AFAIK, they're *all* solid
b) Presumably, this was done as a test, a prototype for a project. Is there
some reason you couldn't use a mortise and tenon, or at least #20 biscuits?
Doug Miller (alphageek at milmac dot com)
Biscuits are usually compressed birch or beech, IIRC. Biscuits are
primarily alignment devices, adding only a tiny bit to strength in a
joint. You're right: M&T would have been better, and far stronger, but
larger biscuits, and even two biscuits, one atop the other (with at
least 1/4" between slots, would have been better.
Too, there's the question of glue. What kind, what kind of clamping and
for how long?
Actually mine are solid wood. You can see streaks in the grain run all the
way across the biscuit. Breaking it exposes a straight line break along the
grain. Looking closely however reveals that the biscuits are stamped out so
that the end grain of the wood is rough for better glue absorption
Were the biscuits dry prior to gluing? They have to absorb some of the
glue and expand in the slot. If the biscuits were kept in a high humidity
area, their ability to absorb glue may have been reduced.
I looked again. I see what you mean. I must have misunderstood a
description that I read online today. My PC biscuits are compressed (of
course), but appear to be from a single piece of wood. I'll sleep well
tonight knowing the truth of the matter. :)
Doug Miller wrote:
Well, if you call a single bicuit-sized piece of solid wood a BIT...
But they ARE made from a single piece of wood, they are NOT made like
particle board or OSB if that is what you are asserting. And usually
Biscuits are Porter Cable brand. Glue is Titebond II. Clamped 3hrs, left
24 hrs. Biscuits are not solid wood, but some kind (?) of chipped wood
pressed together. The breaks were not along any grain. No grain visible.
I have never seen a biscuit that is not solid wood. If you had pieces left
in each half it most likely broke along the grain. If any pulled out of the
slot revealing the original slot surface you may not have had enough glue in
My Take on biscuits ( and I have used them quite a bit
over 10 years or so - as a hobbyist) is that they provide
a lot of lateral "hold" but not necessarily a lot of
vertical load support left to their own "devices" so to
speak. I'm not sure about "alignment" because there is
quite a bit of "play" with biscuits IMHO.
I have not had joints separate when I used biscuits.
I use them for face frames and such (much like pocket
screws) which I would like to start using but hate to start
yet another "software" item in the shop.
Usually, I cut the FF, then cut the slots. After aligning everything
on a cabinet front, I glue up the biscuit then shoot a brad
into the cabinet which holds until the glue dries.
"Until the glue dries" gets you through a lot of
time just waiting for inspiration or whatever.
I have let glue dry for days at a time. Most projects are
better for that.
I know...get the Kreg 2,000,000 etc.
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