"Biscuits are another type of joint and they are just that. Biscuits are not the cure all for every joint nor should they be summarily rejected because in certain situations something else is better. Part of the skill of woodworking is knowing what joint is best suited for each situation, considering time, effort, pay back, look, strength and etc."
Here, here.
One of the most egregious mistakes in the Wood Magazine article that Berry cited at the beginning of this biscuit bashing was not that the tests were poorly designed (which they were) or that the author had an imcomplete understanding of the forces that effect joinery (which he did), but that the article failed to give any clear guiidlelines for how to apply the knowledge gleaned from the tests. Ditto on Norm Abram's off-the-cuff remarks about the weakness of biscuit joints. Weak is what context? They may be extremely weak if you are building a shelving unit to display your cannonball collection. On the other hand if you collect butterflies, then biscuits could be considered over-engineering.
The point being is that Ed hit the nail on the head -- biscuits cannot be used for every circumstance, but they can be used effectively if you understand their strengths and their limitations. Even if Berry would not recommend them to his friends, I would recommend them to mine, provided my friends were not collectors of cannonballs.
Finally, let me say that all of these esoteric arguments about relative shelving joint strengths are reduced to their most ridiculous components when you consider that almost all of us have bought or have made shelving units that suspend their shelves from one of the weakest joints ever devised: 1/4"-diameter pins in holes. Compared to a metal pin in a shallow hole, biscuits joints are darn near indestructable! Yet most of us consider these pins perfectly adequate for supporting shelves that hold everything from books to canned goods to fine china. And you know what? They are.
Ed in Tampa wrote:Scottss
As a faithful viewer of Norm's I think you may be overstating what he actually said. Norm still uses biscuits but is careful on thin wood to place the biscuit off center toward the unseen side so if the biscuit shape is telegraphed to the surface it won't be seen.
I have asked many people if they have ever seen biscuits telegraph their shape to the surface and no body has actually ever seen it happen.
Biscuits are another type of joint and they are just that. Biscuits are not the cure all for every joint nor should they be summarily rejected because in certain situations something else is better. Part of the skill of woodworking is knowing what joint is best suited for each situation, considering time, effort, pay back, look, strength and etc.
Ed
"I have asked many people if they have ever seen biscuits telegraph their shape to the surface and no body has actually ever seen it happen. "
After I wrote this I got an e-mail from my good friend and fellow Shopsmith'er Bill Mayo, (many might know Bill as he repairs SS here in the South East) that he has seen biscuits telegraph their shape to the surface when used in plywood. That may be since the only time I use biscuits in plywood would be to position a face frame to the front of a cabinet. The shape of the biscuit may very well be telegraphed to the surface but I will never know since usually the surface in question is hidden.
Ed
"Telegraphy" in biscuits joints has little to do with the biscuits themselves and more to do with adhesives used to assemble the joints.
Biscuits often will telegraph their shape if you use polyurethane glue for the simple reason that this material expands with a great deal of force as it cures. Biscuits may also telegraph in materials (such as plywood) that don't resist tension/compression as well as solid wood. In plywood, you don't want to use polyurethane glue because it expands and alphatic (yellow) or polyvinyl (white) glues because they shrink. If you must use biscuit joinery in plywood, it's best to use epoxy adhesives. These neither shrink or swell, but remain at roughly the same volume as the catalizer hardens the resin.
