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Thread: How much weight will biscuits joints hold?

  1. #1
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    How much weight will biscuits joints hold?

    Im about to begin a small liquor cabinet, two shelves, simple construction.
    3/4 oak ply for walls, 1.5 square red oak legs.
    Im not sure if I use biscuit joints if it will hold the load of two shelves full of assorted bottles.
    Is there anyone who knows how much weight each biscuit will bear?(size 20)

  2. #2
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    No I don't but I would never trust them for any more than a few pounds. There made for alignment, not strength. I think you need to look at something more substantial. A shallow dado would be a huge improvement.
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  3. #3
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    Quote Originally Posted by Jeff Horton View Post
    No I don't but I would never trust them for any more than a few pounds. There made for alignment, not strength. I think you need to look at something more substantial. A shallow dado would be a huge improvement.
    Agreed.

    A 1/16" dado would do way better at supporting shelf load than filling the same edge with biscuits, and it's easier to keep lined up that way, too, since you can cut the dados for both sides without changing your fence setting (just don't make sure you get yer lefts and yer rights straight, or you might have to make multiples of the cabinet!)
    Jason Beam
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  4. #4
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    not attempting to sound like I dont know what Im doing(its tough to hide certain facts), but I was under the impression that biscuits supply a pretty decent joint due to the swellling. I thought it was used for joints, maybe not very strong joints, but I thought a biscuit every 6 inches or so would supply sufficient strength.

    I think IM not making it clear as to my design.I was going to attach the side walls to the legs, which will run from floor all the way up to top of cabinet.(about 6 inches clearance from the bottom of leg to bottom of cabinet) I was going to attach the sidewalls, along with 2 support "aprons" in the back, and a face frame in the front, then attach the bottom and upper shelf with a dado on the inner walls.
    I was using the biscuits to attach the legs to the side walls, as in a table apron, I just didnt know if all that weight would turn the walls inward and not offer enough support. The bottom and the shelf will be dadoed into the side walls, so I figured alot of the cabinet strength would be in the wall attached to the legs.(ofcourse my design could be totally flawed, but I have to go with what I think and know I can handle)
    Last edited by allen levine; 06-06-2008 at 09:12 PM.

  5. #5
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    allen without seeing a sketch,, i am thinking you could hide a couple of screws behind your face frame to attach your legs with.. that screw shear strength is enouff for what your up to if i have understood you correctly.. if you coiuld just draw a sketch of what your up to and then scan it in to let us see your idea it wopuld help emesnsly or take a pic of your sketch wil work to.
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  6. #6
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    asking me to draw something, hahaha.......youd have better pictures from a 4 y/o with crayons......but I drew this before I left work, measurements arent in it, figure total height around 42 inches, total width, approx 24-26 inches
    Legs will extend 4-6 inches below bottom of walls.
    Face frame in front will be biscuited on, then 2 or 4 doors.
    Shelves dadoed in bottom of side wall, and middle. Oak ply for shelves and walls. Id screw on a 1/4 " oak ply for the back.


    If I knew basic furniture construction, I wouldnt be asking.
    If I was smart, Id get someone here to build it for me, but then Id have no fun messing up everything.
    heres a very, very rough sketch of whats in my head.(dont know if it will help, but at least I proved how much of a beginner I am, and not too ashamed of it, cough, cough)

    Now that I looked, it doesnt help that much.

    I was thinking I could use something like a half lap joint between the ply and legs, cut out 3/4 of an inch on the inside of the legs, attach with glue and screws, but I dont know how oak ply would cut for a half lap joint, never tried.(I have time to think about it, I have most of the wood, but Im going to experiment with Mahogany and Cumaru, making a chair out of each, and I promised alot of chairs before the summer ends, going to make around 60 bucks a chair, not what Im doing it for, but I get egged on by my wife if Im going to build it for someone else, they want to pay, they are getting a tremendous bargain, I should just take the profit and buy myself more tools)
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    Last edited by allen levine; 06-07-2008 at 12:53 AM.

  7. #7
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    Allen,

    The guys are right. Bisquits give no strength. None. Zippo. They're just there to help you align the pieces. That's why I've put my bisquit cutter away. Couldn't find it if I wanted to...

    On the other hand, a long grain to long grain glue joint might just hold a good long time, if done properly. Do you have a jointer?

    I've heard people criticize dadoes and half laps that are long grain to end grain, but I have the impression that argument's for purists. So far mine have always held...

    Thanks,

    Bill

  8. #8
    Quote Originally Posted by Bill Lantry View Post
    Allen,

    The guys are right. Bisquits give no strength. None. Zippo. They're just there to help you align the pieces. ...

    Can't agree with you on this Definative answer. true they add little strength in the shear factor across the biscuit bit they do serve a good alignment and lengthwise shear strength but due mainly from the adhesive along the joint. So there is some strength added by their use as well as the alignment issue.

    The biscuit acts similar to ever popular Loose Tenon that is so popular these days, the strength is in the structure of the Tenon, just as with the Biscuit, so try breaking a biscuit across and lengthwise, You can snap it laterally but to shear is quite impressive. Make up a test piece and using good adhesive and given suffencient time to allow glue curing completely , snap the piece and you will fint the wood fails either side of the Biscuit, not at the buscuit, the biscuit will stay intact and the wood will fail, so where is the strength? In the adhesive and the compressed football biscuit.

    I too don't use mine much but when I do it is for alignment and quick assembly but I don't discare its value, For it is just another tool in our Arsonal of Goodies.

    From the sketch I would suggest that biscuts 3"-4" apart will add some stability and strength, But the effort to cut a slot and cut a mortise into the legs would be near the same and to slot the panel or cut a tenon would also be the same and a M&T panel would be VERY strong and fit your need better. And make those Biscuit Neigh-Sayers happier.
    Last edited by Bill Simpson; 06-07-2008 at 03:02 PM.

  9. #9
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    Quote Originally Posted by Bill Simpson View Post
    Can't agree with you on this Definative answer. true they add little strength in the shear factor across the biscuit bit they do serve a good alignment and lengthwise shear strength but due mainly from the adhesive along the joint. So there is some strength added by their use as well as the alignment issue.
    Bill,

    So I dug a little deeper. You're right, the wood magazine test showed an end grain to end grain butt joint breaking at 139 pounds of force, and the same joint with bisquit breaking at 220. Not a big difference, but something.

    Here's a start for research:
    http://www.google.com/search?q=Wood+...ient=firefox-a

    and an actual video of the test:

    http://woodmagazine.com/jointtest

    Thanks,

    Bill

  10. #10
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    my 135 lb daughter sat on my telephone table I just finished yesterday, to test the height, it held, made with biscuits. (she wanted to tell me about how high to make her coffee table, so she sat on the table to see about how how her couch is, my heart stopped for just split second, didnt make that tiny thing for so much weight)


    Im going to get a dado set, I cant continue making walls and bottoms and shelves using a handheld router, its hard for me, confusing at times, and a dado blade seems just such a simpler path to take.
    I think Ill attempt to mortise the legs, can go up to 3/4 inch deep, and then I can put 2 screws, one at top and bottom, from inside, coutersunk, and it would hold the weight.I thought a half lap kinda joint between the panel and leg with a few screws would hold it just as secure, or secure enough, but I guess if Im using the dado blades, the cuts will be similar in task.
    I appreciate the input.(i really love the biscuit cutter, Im sorry I wont get a chance to use it. When I got it, I told my wife I just took many years of joint learning off my list)
    Last edited by allen levine; 06-07-2008 at 04:26 PM.

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