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to biscuit or not to biscuit

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Blog entry by richgreer posted 01-09-2010 09:08 PM 4993 reads 0 times favorited 18 comments Add to Favorites Watch

Several members of my local woodworking club believe that biscuits add no additional strength when gluing up most boards. They (and I) believe that they are helpful if you are gluing up boards that are oily and do not normally glue up well. They (and I) also believe that in certain situations the biscuits can aid in alignment. I will also add that I like to use them when gluing into end grain.

However, when making a table top by glueing up oak, walnut, cherry, etc. boards side to side, most of the woodworkers I know (including myself) no longer use biscuits.

How do others feel about biscuits?

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.



18 comments so far

View IkeandBerry's profile

IkeandBerry

45 posts in 1921 days


#1 posted 01-09-2010 09:34 PM

I have used biscuits before but only for alignment purposes. They do not really add any strength to the joint. If you get the mating surfaces as flat and smooth as possible the joint will be stronger than the wood itself. The test of this is to do it with some scrap and then try to break it along the glue joint. Almost every time the joint wood will break to either side of the glue joint. The most important thing is to make sure that the mating surfaces are as smooth as possible. This keeps are from getting into the glue and the joint making a stronger joint. I usually do not use biscuits at all anymore, because if you off a little bit then it makes the glue alignment off and the entire glue up can be wasted.

-- There is nothing like the sound of a hand plane passing across a board in an otherwise quiet shop.

View pmayer's profile

pmayer

574 posts in 1722 days


#2 posted 01-09-2010 09:36 PM

I wouldn’t bother using them in an edge joint application. I think they can cause more problems than they are worth, and they slow the process down. If you are careful when gluing, you can get better alignment without them in my experience.

In an end grain joint, I believe that they do add strength compared to a butt joint, especially if you are using thick enough stock to use a double biscuit joint. For small tables and other lightweight items, I use biscuits commonly and have never had a biscuit joint fail. It takes considerable force to break this joint. Yes, M&T is stronger, but I rarely put 500-600 pounds of force on my accent tables. :) For something that is subject to a lot of racking force, like a chair, dining table, etc., I would not use biscuits, but I am less reluctant with them than most woodworkers I would say.

-- PaulMayer, http://www.vernswoodgoods.com

View GMman's profile

GMman

3902 posts in 2354 days


#3 posted 01-09-2010 10:20 PM

I have used biscuits both to aglinment and strenght after watching Norm’s New Yankee Workshop Sow it is what he said.

View richgreer's profile

richgreer

4524 posts in 1731 days


#4 posted 01-09-2010 10:30 PM

It is my observation that Norm is using biscuits less often than he used to. He used to be a big advocate of biscuits. However, in a recent episode I noted that he did not use biscuits on a table top glue-up and he commented on how, in this application, biscuits were not necessary.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

View Geedubs's profile

Geedubs

143 posts in 1886 days


#5 posted 01-09-2010 10:30 PM

This is a good question and there obviously are varying perceptions. Ironically, I just watched this morning a video podcast on simple jointing methods, including using biscuits. Here is the perspective of Joel Hess with Woodshop: http://www.woodworkingonline.com/2008/03/26/podcast-33-quick-easy-joinery/.

-- Todos los dias aprendemos algo nuevo.

View GMman's profile

GMman

3902 posts in 2354 days


#6 posted 01-09-2010 10:54 PM

Ask This Old House on now and they are using bicsuits

View GMman's profile

GMman

3902 posts in 2354 days


#7 posted 01-09-2010 11:11 PM

Geedubs…very good video too back the woodworker is a little slow saying what he is teaching ....lol lol

View hObOmOnk's profile

hObOmOnk

1381 posts in 2784 days


#8 posted 01-09-2010 11:13 PM

I use doweling jigs and pegs.
  • Cheaper than biscuits.
  • Stronger than biscuits.
  • More flexible than biscuits.
  • No special tools needed, just a drill – even an old-fashioned brace and bit will work.
  • Can be a good substitute for mortise and tenons.

Heck, I even make my own pegs.

Before biscuits there were pegs, and they are good.

-- 温故知新

View nailbanger2's profile

nailbanger2

962 posts in 1800 days


#9 posted 01-09-2010 11:29 PM

Now you tell me!

-- Wish I were Norm's Nephew

View SCOTSMAN's profile

SCOTSMAN

5373 posts in 2242 days


#10 posted 01-09-2010 11:45 PM

I got very frustrated with biscuits and sold my dewalt biscuit joiner and have gone back to dowels which are much easier to align and set up everything before gluing.Alistair

-- excuse my typing as I have a form of parkinsons disease

View richgreer's profile

richgreer

4524 posts in 1731 days


#11 posted 01-09-2010 11:53 PM

Scotsman has inspired me to make this comment – - Festool offers their domino joiner and Freud has a doweling tool. The Festool is very expensive and the Freud is more reasonably priced and both have positioned themselves as an alternative to biscuits. I have neither but I think about the Freud often.

Does anyone have experience with either and/or a comment on either as an alternative to biscuits?

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

View jlsmith5963's profile

jlsmith5963

297 posts in 2005 days


#12 posted 01-10-2010 01:41 AM

If memory serves within the last few years FW did a strength test on various types of joints (including biscuits) and again if I remember correctly the biscuits did not add much in the way of strength. (of course it could all be a false memory)

-- criticism: the art of analyzing and evaluating the quality of an artistic work...

View closetguy's profile

closetguy

744 posts in 2549 days


#13 posted 01-10-2010 02:40 AM

I use biscuits all the time. This lack of strength argument is surprising to me. I accidentally dropped a large face frame window seat I built with biscuits off the back of a truck onto hard pavement a couple of years ago. The whole thing exploded into pieces. What were the pieces? The biscuits stilled glued to the wood. The wood (popular) actually broke off around the biscuits, but the biscuits held.

I guess it is different strokes for different folks. I find biscuits 10 times faster than dowels, excellent alignment, and allows me to make minor adjustments if I’m a hair off. Oh, did I mention the strong joint?:)

-- I don't make mistakes, only design changes....www.dgmwoodworks.com

View jlsmith5963's profile

jlsmith5963

297 posts in 2005 days


#14 posted 01-10-2010 03:56 AM

I went and found the FW article online (requires membership) I don’t know how many people actually use a double biscuit joint, which is what was tested.

Biscuit joints—
In the past 20 years, biscuit joints have become
popular with some furniture makers. I suspect that the #20 biscuit
is the most common; I use this size primarily for alignment of solid
wood and when working with sheet goods. Previously published
tests have suggested that biscuit-joint strength and stiffness
were comparable to mortise and tenons, but that when biscuits
fail, they fail suddenly, Before we tested them, I reasoned that they
would be significantly weaker than either type of floating tenon or
traditional mortise and tenon because the biscuits are thinner and
don’t offer as much glue area. I was only partly right.
The double #20 biscuit joint put in a respectable performance,
but its average maximum working load was about half the strength
of the mortise-and-tenon joints. The graph compares the maximum
working and failure loads for the mortise-and-tenon and biscuit
joints we tested. It is surprising to note that although the plastic
region (in which irreversible damage occurs) is relatively small,
the load curve is gently rounded, and the tail is long. This indicates
that 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, even after irreparable
damage occurs. However, relatively long after technically defined
failure—when parts physically fell apart—it was sudden and complete,
with the joint showing no residual strength.

-- criticism: the art of analyzing and evaluating the quality of an artistic work...

View a1Jim's profile

a1Jim

112103 posts in 2234 days


#15 posted 01-10-2010 04:52 AM

Like all type of joints biscuits have there place I have found them to be much stronger than dowels and I feel there much more forgiving where dowels need to be dead on. I’ve read reviews from FWW and depending what review of theirs you read They rate biscuit joinery rather highly. This is all subject to how many biscuits,what type of joint and what type of wood that joint is in and what kind of stress factor the project has it’s used in. This subject is kind of like finishing, people recommend what there used to using.

-- http://artisticwoodstudio.com Custom furniture

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