Replies

1. 
   CStanford_ | Feb 25, 2000 05:26pm | #1

   *
   Nothing is stronger or more suitable for the joinery that you mentioned than the traditional mortise and tenon joint. A well-cut and assembled biscuit joint may very well be STRONG ENOUGH, but it will never be AS STRONG as a well-cut and fitted mortise and tenon joint. Do you see the nuance?

   Biscuit joinery is fast; if speed is an issue then use it. If speed and "production" are not important issues in this project, then use M&Ts.

   I think that plate joinery is more appropriate in a quasi-production setting where you have to pump out a lot of case joinery (lots of bookcases or kitchen cabinets). For 'one-of' furniture building I don't think it adds much to the mix.

1. 
   Mike_King | Mar 27, 2000 08:45pm | #2

   *I'll back up CStanford's comments. I just built a set of eight barstools using biscuits where I'd previously used M&T joints. I honestly don't know if it saved me any time or not. Since I had angled aprons, angled and tapered legs I had the same kind of fitting hassle that M&T's would have needed, and I still had to compound-angle drill legs for rungs, and dowel-tenon the rungs, screw and plug the curved backs.. Come to think of it.. it definitely was an experience.. and a perfect case for an Omnijig! ..I think I missed my chance..

1. 
   lionel_louviere | Nov 13, 2001 12:28am | #3

   *why don't you use the bead lock joinery system. it makes a loose mortise and tenon joint using a jig, drill bit and special design tenon. Woodcraft has them.

1. 
   Matthew_Schenker | Nov 13, 2001 09:53pm | #4

   *When used in the right context, biscuits are very good. I use bicsuits for several operations, but I turn to mortise and tenon whenever there's a lot of stress on the joint.Fine Woodworking did a study a little while back on various types of joints and their strengths. What they found is that biscuits are stronger than most people think. But, the real question is, how does a joint fail? This sounds like a small question, but it's not. What the FW study found is that mortise and tenon continue to be very strong, even after the joint begins to fail. But when biscuits fail, they tend to fail more completely.However, if you incorporate other joint-strength elements into your peojects, biscuits may be a good idea. For example, you can use biscuits on table aprons, but strengthen the corners against the table legs and you'll probably going to be just fine.In the end, you might find that doing good biscuit joints does not save you too much time. I have to discard about 1/3 of my biscuits (even though I started using Lamello). You have to make sure each biscuit goes into the slot snugly -- it should meet with some resistance, but not be too tight. Dry test every biscuit in both halves of the panel. If you have to pull the biscuit out with a wrench, it's too tight. By the time you get all this set up, you start asking yourself if mortise and tenons are really that much more time consuming after all.One hint: I would stay away from Porter+Cable biscuits. Somehow, they have populated all the hardware store shelves. When I used to use the Porter+Cable biscuits, I regularly threw away over 50% of them. Also, I did a shop test on their strength, and was amazed to see how easily they snap down the middle, as compared with Lamello. The Lamello biscuits are a bit more money, but they are much better and are the only ones I use now.

1. 
   Danford_C._Jennings | Nov 13, 2001 10:39pm | #5

   *Matt,Suggest you re-read the article; biscuits were the weakest in all catagories.

2. 
   Matthew_Schenker | Nov 14, 2001 05:56pm | #6

   *Dan --I stand by what I said. My statement basically is that biscuits tested to be stronger than most people would think, but that when they fail they fail completely. I also stated that biscuits have pretty good strength for some applications. Everything I said is supported by the article.If you read the text, and do not just look at the graphs, you'll see the point is that joint failure is not a simple thing. There is strength, rate of failure, and strength after failure begins. If the article were just stating which joint is stronger, they wouldn't have published it in FW, since most woodworkers already know that mortise and tenons are stronger than biscuits. The article illustrates when and how various types of joints fail. For example, the author states that dovetails are stronger than biscuits, but that dovetails fail even more suddenly than biscuits. As a matter of fact, the article shows that wide-pin dovetails can take high pressure, but they fail extremely abruptly.The FW article clearly states that the author found biscuit joints to be stronger than expected. To quote from the biscuit section of the article: "Failure, as defined in this article, is not as sudden as others have suggested. Clearly, the joint is able to sustain a significant load over a wide range of joint movement." This is consistent with my previous statements.Of course, the author also notes that biscuits can only handle about half the load that a mortise and tenon can handle, and, more importantly, when biscuit joints fail, they fail more completely than mortise and tenons. To quote again: "...relatively long after technically defined failure--when parts physically fell apart--it was sudden and complete, with the joint showing no residual strength." Again, this is consistent with my previous statements.The author also states that biscuits are very good for aligning solid wood panels. This is mainly what I use them for.Take a closer look at the article.

3. 
   Bill_Duckworth | Nov 15, 2001 11:25pm | #7

   *I'll jump in as the referee here, Matthew and Danford. It's an easy job, because you're both right. I believe you guys are talking about two different articles. In an article in FWW issue #111, pp. 58-61, biscuit joints fared well in stress tests. In another article in FWW issue #148, in a whole different set of tests, biscuit joints didn't do so well.

4. 
   Danford_C._Jennings | Nov 15, 2001 11:58pm | #8

   *Actually Bill,Matt and I are refering to the same article (#148). Just a difference in interpertation and my heavy bias against biscuits.Frankly, I'm surprised that I even posted here in the first place, since this discussion started 10 months ago and was "dead" for nine.Dano

5. 
   hotsawdust* | Nov 16, 2001 06:17am | #9

   *Biscuits are perfectly adequate in many situations, and perfectly inadequate in many others. Furthermore, there are many situations where they are the best joint (by best I mean strength is completely adequate, and they are the fastest and thus most economical to cut.) They are used extensively by european cabinetmakers and have been for 40+ years. Being "against" biscuits is like being "against" nails: in a situation where they are the most appropriate joinery method why not use them? For much carcase joinery, both solid and plywood, they will make you money compared to other construction methods.That said, any joint subject to racking (chair legs, bed legs, table legs are good examples) are a bad place to use biscuits. In these cases the stress on the joint can easily overcome the strength of the biscuit: use a good M&T every time in these joints..

6. 
   CStanford_ | Nov 16, 2001 04:26pm | #10

   *The original post is just a few months shy of being two years old.

7. 
   Matthew_Schenker | Nov 16, 2001 04:40pm | #11

   *It's not the age of the post that matters...I think Hotsawdust sums up the biscuit situation pretty well. What you said also describes my way of using this joinery method. For those times when biscuits are the right kind of joinery (face frames, case strengthening, sheet alignment, etc.) I am happy to use biscuits, and will continue to do so.With that said, I can see how Danford might feel that biscuits are overused by some woodworkers, or how biscuits can be misused and treated as fine woodworking, which they are not.I wish FW would write on biscuit quality, however. I have found that to be a real issue, as I said in my previous post. All those people out there using Porter+Cable are making Danford even more upset about biscuits!