The biscuit joint doesn’t give you the strength you’ll get with a mortise and tenon. It’s now more years ago than I care to think about, but loosely said, it was a comparison of the strength of mortise and tenon joints and dowel joints. So if the mortise and tenon joint is inteded to aid in alignment of a piece rather than creating a strong joint, I say go ahead and biscuit away.
What We Hear Most & Agree With Is This …. Biscuits joints serve best as a quick and easy way to keep glue-up parts in alignment, and that they add appreciable pull-apart to strength joints that would be otherwise too weak to stand on their own – like butt joints and miter joints. We’re guessing that most woodworkers will find more use for a biscuit joiner, with its ability to invisibly align and secure joints so quickly. Doweling also makes for a stronger joint, and if you own a drill, it’s less of an initial investment: You just need a doweling jig and a few drill bits.
The one thing I got out of that is that while there are folks who balk at the price of festool’s “Domino” system, there doesn’t seem to be the same level of distaste for it on the basis of usefulness as there is for “Biscuit” joinery. As an owner of a domino joiner and a Rolex, I can tell you that the domino joiner has a lot more use than the watch. The great thing is you can experiment and find uses beyond the biscuit or Domino.
A Domino gives you all of the strength of a dowel type join and also gives you the added bonus of being usable in much smaller joins unlike a biscuit. A Domino joiner is somewhat of a hybrid between two different types of joins; a biscuit join and a more tradition dowel joint. A Festool Domino joiner is extremely expensive and a high quality biscuit joiner can be up to 1/5 the rice of the introductory Festool model.
biscuit joiner vs mortise tenon Related Question:
Are biscuit joints stronger as mortise and tenon?
When done correctly, a biscuit joint is at least as strong as a similar size mortise and tenon joint, and decidedly stronger than a dowel joint.”
What are the disadvantages of a biscuit joint?
Biscuit joints do not stand up well against other joinery methods. We won’t spend any time comparing with mortise and tenon joints because all other joinery methods pale in comparison when measuring strength. But, as an example, the use of dowels as opposed to biscuits is a step up in strength.
Are biscuit joiners worth it?
They will definitely provide more strength than glue alone, but not a lot. If your boards are too narrow, you can reinforce the joint by adding the biscuit on the back side of the face. But again, I would prefer to just use pocket screws, dados, or rabbets.