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 each piece. 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 too.
My questions are: a) What kind of biscuits are you using, anyway? AFAIK, they're *all* solid wood. 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?
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
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 the slot.
See the second paragraph in the article at:
Lamello has come out with a new biscuit called "Fibro". It's supposed to give high omni-directional strength and it is not humidity sensitive. See:
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.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.
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.
Ok, Ok...
Lou
No biscuit I've ever seen. You might want to look again.
Yeah, really. I want to know too, so I don't buy them.
P-C biscuits are solid wood, with the grain running diagonally across the biscuit. They're stamped and compressed, not machined, but they *are* solid wood.
Look again. You missed it the first time.
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. :)
Dave
Doug Miller wrote:
PC brand biscuits are of lower quality than is acceptable for a commercial shop. You want Lamello.
most biscuits are very dry, very compressed wood fibers, usually beech.. the theory is, when the moisture in the glue hits them, they expand.. I can buy into this easily, after my one attempt at gluing one side of a joint first, as I would do with dowels.. the biscuit didn't fit in the slot on the other piece any more..
mac
Please remove splinters before emailing
maybe they have a bunch of elves running them through those food dehydrators that they have infomercials for?
mac
Please remove splinters before emailing
You didn't forget the glue, did you? (kidding) But, it does sound like there was a problem with the glue or gluing technique used. BTW, normal biscuits ARE made from solid wood, usually beech, that is machine compressed so that they expand after absorbing moisture from glue or surrounding wood.
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