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Biscuit use?

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  • Biscuit use?

    I got in the habit of using biscuits for all my edge joining applications (mostly tabletops and desktops). I find that waiting a week for the swelling of the wood to go down from the moisture introduced via the glue prior to final surface planing or sanding to be very annoying. It just occurred to me that using biscuits has been an enormous waste of my time and the joint would be sufficient without the use of biscuits. Am I missing anything here, do the biscuits serve any real purpose in this type of application, besides possibly aiding in the alignment?



  • #2
    From the standpoint of joinery and physics, it appears to be a stronger joint. There is alot of force on joint glued just at the edges. Same way that mortise and tennon joints are so strong.

    Just an educated guess.



    • #3
      The glue does most of the work. The biscuits assist in aligning the boards together during glue up.



      • #4
        I haven't ever noticed any swelling on my edge jointed table tops( doesn't mean it didn't happen). What kind of wood and glue are you using?


        • #5
          The swelling is very minute, but enough that I can feel it by running my fingers over it and I just assumed that it I smooth it out at that point it would leave indentations when the swelling subsided. Wood used is Red Oak and Mahogany and original Titebond glue.


          • #6
            From what I have read biscuits help with alignment and a stronger joint. I did not say you needed it, it may be strong enough without it. I like them, males it easier for me. Never noticed any swelling.


            • #7
              I use biscuits and find that I use the Kreg 2000 jig/pocket screw system more, which is faster and I think because there is no slot or biscuit to allow glue into the interior of the joint it does not swell much or at all. I know that some people soak the biscuits first if they use Gorilla glue, which is not waterbased and does not swell much,even with mdf. Joints using Titebond II(waterproof) also does not seem to swell as much,it sets faster. On Pergo floor installs, that have glue joints, you want the seam to swell for a good bond. The swelling is cause by the glue absorption into the particleboard core and will disapear in 24 hrs.


              • #8
                Biscuits when gluing long grain only aide in alignment and add little to strength of the joint. They do add to the joint when doing end grain and miters. When I use them I only glue one edge of the biscuit to allow for movement. This might take some of the moisture problem away. Splines add strength and alignment especially for tops etc and I find them easy and fast to use once you get a routine down. Good Luck


                • #9
                  My rough rule of thumb is to use biscuits for larger glue-ups and skip them on smaller jobs. While alignment has been the main advantage of biscuits, they aren't the total answer---care must still be used in cutting slots---I've experienced the slight edge mis-alignment spoken of, on more than one occassion and would say the glue issue may be valid, since dry fit runs have netted better results than actual glue-ups in some cases. I would say, however, biscuits are superior to dowels. As to pocket screws, well, they have their place, but I seriously doubt I'd ever use all the applications promoted by Kregg, etc.


                  • #10
                    A professional's opinion for table top glue-ups in FWW Dec 2003, "Gluing up Tabletops", Rogowski. He basically say that biscuits are only needed for alignment when gluing long grain to long grain. However, they will add strength when gluing short to long or short to short grains.

                    There is also an article in that issue that describes how glue works. It allows you to extrapolate glue ups for any type of joint you could imagine.

                    [ 01-02-2004, 01:19 PM: Message edited by: yogibear ]


                    • #11
                      I have never used bisquets, and I'm sure they have their place. I am of old school and I still prefer the dowel method when reinforcing and aligning glue ups is neccessary.

                      I may invest in a bisquet jointer someday, but no immediate plan to do so.
                      John E. Adams<br /><a href=\"\" target=\"_blank\"></a>


                      • #12
                        Some time within the last 18 months or so, one of the magazines ran some destructive tests in order to see just how much strength biscuits added to a glued joint. The results surprised everyone: biscuits did add a significant measure of strength to every joint tested.