Why not biscuits

[Douglas Brummett]

round 2

For round 1 discussion see:
http://www.sawmillcreek.org/showthre...hlight=biscuit

Okay, background of the question...
Dining table, compact base, poplar
I went back and forth a bit on the joinery for this table. In the end I chose to go the path of expedience and accuracy. So I used a but joint with 2 #20 biscuits to attach the 1.75" aprons to the 3.625" legs. For a little insurance I used 1.125" x 3" glue blocks inside backing each joint.

This fast construction allowed me to go from rough cut stock to jointed, planed, tapered legs, and assembly in a single day.

I ran a sample piece with dual #20 biscuits, but joined. Even after about half an hour the joint took an impressive beating with a hammer before failure. Failure was not on the glue joint, but back in the biscuit socket where the glue hadn't fully cured. So I felt fairly confident in this construction for the table. Note that I did add glue blocks to reassure myself.

It seems that discussion on this topic quickly turns to tests that don't really apply, a naysayer bandwagon, and a whole slough of everything from buy a domino to only mortise and tenon. Opinions are like...
...well, you know. So lets try to avoid going the path of round #1.

For round number 2 I want to see a clean fight. If you have never used biscuits to attach an apron to a leg then please maintain voyeur status on this thread. If you have tried this please let us know the outcome. Personally the table I glued up this way feels rock solid. I have read of accounts of others building many tables this way, one was a furniture maker who claimed he had never had a failure.

So there it is. I am going to go find my flame retardant keyboard before it gets to hot in here.

[Bill White]

I'm old and brave.
I've never been unhappy with my use of biscuits. Have used 'em on table tops, leg attachments, etc.
On a rather large and heavy breakfast area table I used M and T.
Two end tables for the DIL I used the biscuits.
Probably try to fit the form to the function if you know what I mean.
Tall cabinet shelves-biscuits.
Bill

[Chris Padilla]

For more fodder, do some searching on Dowelmax. They had some interesting tests.

[Peter Quinn]

I have not made a table this way, or used biscuits for any similar structural application, but I have used biscuits often and am familiar with their strengths or lack there off. I have also not jumped off the Brooklyn bridge, but having walked over it and having fallen from much gentler heights I would advise against it. I enter this conversation in the same spirit.

It is not that biscuits don't offer any strength, but I doubt they have the strength to resist the shear forces a group of my friends and family are capable of exerting on a table during a get together. Perhaps your acquaintances and dining guests are more civilized? I rarely build anything I don't want to serve its purpose for years. I can snap a #20 biscuit in my hands, and last I measured, it was little more than one inch across, divide that by two, you have barely a 1/2" by 1/8" projection into the stock on each side at the deepest point. This may be enough to resist your hammer blows on a small sample, but when ten of my friends and i get to eating and drinking and the fulcrum becomes the span of the table and the base of the leg, your biscuit joint is doomed.

I have built small pieces of furniture like a side table or TV stand with biscuits and had good success, but these are not subject to the same stress over years as a dining table. They are also part of a design that doesn't require more of them than they are able to provide. My own store bought dining table is built with stub tenons and a steel angle bracket pulled together with a hanger bolt at the corners. Your basic factory approach, but it remains solid after years of use. I'm not a purist that will insist on M&T joints as the only sound road, but biscuits may be a lower road than I am willing to trust in the event of a flood.

In your case the glue blocks may add enough strength to keep things together. But I like a table built for those rare occasions when a grown man decides to get up on the table and do the hula dance and several of his friends decide to join him!

[Fyrman Dave]

But I like a table built for those rare occasions when a grown man decides to get up on the table and do the hula dance and several of his friends decide to join him!

I'm afraid I would "un-invite" any friends that treated my furniture like that.

[Phil Thien]

In my testing I've noticed that the biscuit itself is often the point of failure.

I've also noticed that plywood biscuits are available.

In many of the tests I've seen they've used a single, smaller hardwood biscuit. It would be interesting to try multiple plywood biscuits, instead.

BTW, I have no concern about biscuit strength overall. Even in cases like a table with no lower stretchers/stringers to provide additional support (and where the leg can act like a lever), I think a couple biscuits with a glue block could be sufficiently strong.

I'm just saying that plywood biscuits may make the joint even stronger.

[Robert Chapman]

Phil - can you describe the "plywood" biscuit and where you get them? I've never heard of them.

[Joel Goodman]

Years ago, I built a round dining table about 52" diameter with the 5/4 apron attached to the thick legs with I think 3 or 4 biscuits per side. I am amazed but 15 plus years later it is rock solid. The aprons were curved so that there was more width at the ends to join (and biscuit) I have stood on it a few times and it was trucked across the country. I would however go with lose tenons at minimum if I was redoing it today. Not that much more work and stronger -- although I guess strong enough is strong enough!

Woodhaven used to sell a plywood biscuit to go with a router bit but they were a little smaller than the large standard type biscuits so I'm not sure of the gain in strength.

[Rick Fisher]

I used #20 biscuits on a coffee table about 7 years ago. They held the aprons to the legs. The joints eventually let go after about 5 years.

It was probably my fault in some way or another. It was as if the glue just stopped holding.

[Bryan Berguson]

I used biscuits to build a coffee table too only it was about 10 years ago and it has not failed. One of my very first projects and a very special one. The wood (hard maple) came from trees that were cut down from my parents front yard. I made the table as a birthday present for my Mom. It needs a little tlc now on the finish but structerally it has held up well.

Bryan

[Phil Thien]

Phil - can you describe the "plywood" biscuit and where you get them? I've never heard of them.

http://www.woodworker.com/cgi-bin/FU...ood%20Biscuits

[William OConnell]

I use biscuts mostly for alignment issues and really don't rely on them as a much as a mechanical fasteners or joint'
Coffee table maybe , Dining table not me. To much time and effort into the work. Why not pocket hole screws? Just as fast really, and vastly stronger. Or if your a purist a Mortise and Tenon.
Thats my spin on biscuts in this application

[Bond Turner]

In my opinion this is a great representation of how people think today, only for the short term. If the whole idea is to build the table as fast as possible than yeah great, biscuits suit your needs, but they will not stand up over time. The good news is that when you will need to repair it you can do a biscuit again, very quickly, and again, and again...

Part of the joy of building fine furniture or even practical furniture is spending time to build something that will last. To me nothing brings greater joy than orchestrating a perfect fitting M&T joint that I know could handle any number of my friends dancing on the table. It took me a little over 9 months to construct and finish a 12 foot dining room table that I still have 12 years later and it still feels as solid as it did when I completed it after many friends dancing on the table. Take your time, do it right and it will pay dividends in the long run.

I think this belief could extend to the rest of the short sighted...investors, bankers, husbands, wives, etc.

Hope I did not offend anyone.

BT

[Charles Seehuetter Panama City]

Phil - can you describe the "plywood" biscuit and where you get them? I've never heard of them.

It may have been answered already but this is where I get mine and I use a lot of them.
http://woodworker.com/cgi-bin/FULLPR...ARTNUM=138-089

I haven't had a failure yet. Some fit a little tight in slots from my Dewalt biscuit jointer but a little tapping sets them in.

[Phil Thien]

In my opinion this is a great representation of how people think today, only for the short term. If the whole idea is to build the table as fast as possible than yeah great, biscuits suit your needs, but they will not stand up over time. The good news is that when you will need to repair it you can do a biscuit again, very quickly, and again, and again...

...

Hope I did not offend anyone.

BT

No offense taken. There is a great article if you google "biscuit-joinery-abstract" (it will be the first hit). They're actually much stronger than most people think.

And I don't think the original poster's table is going to repeatedly fall apart.