# Failed Biscuit Joint



## clarionflyer (Apr 27, 2008)

I thought this was interesting.
I made this oak garbage can 'bout a year and half ago. Came out pretty good. But the other day I noticed that my biscuit joint on the top piece failed. The glue held, unfortunately the end grain of the oak failed. 
It has very little load, just the shock of the door closing on it 20 times a day.
Just wondering if this is a common failure? I have to rebuild a new top for it, but I'm afraid of using the same type of joint.


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## Sawduster (Dec 30, 2008)

That would be disheartening. I don't think oak has that much structural integrity in a situation like that. I wonder if pocket screws might be better there.


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## BHOFM (Oct 14, 2008)

I prefer to use dowels and rabbits to get a better
glue area.

It looks like a combo, wood, glue failure. Did you clamp
the joints good at the time of the build?


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## Barry Ward (Mar 22, 2008)

*failed biscuit joint*

I agree that dowl rods or pocket screws would be a much stronger joint,as butt joints are about the weakest area you can try an glue up.I know others will disagree,but I said this before that biscuits offer no structural strength,there ok for lining up boards for edge gluing an thats about it.


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## thekctermite (Dec 23, 2007)

I agree that the butt joint is inherently weak, and the end grain failure isn't suprising. Dowels would be stronger since it leaves more of the end grain intact. Pocket holes would be even stronger since none of the end grain material is removed.

Through dovetails would probably be the strongest way to do this joint.


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## ch0mpie (Nov 10, 2006)

Seems to me that the failure is not of the biscuit, but of the wood closest to the end grain whose fibers have been sheared by the biscuit slot. I think that dowels or pocket screws may be a little stronger, but generally would be subject to the same sort of failure. Won't a dovetail joint be most appropriate?


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## skymaster (Oct 30, 2006)

Biscuit is doin fine :}:} Da Oak failed, that said from pic that joint can be repaired, all pcs seem to be there Tbond2 the critter, clamp it and it should be ok. If nothing fits inside that pc, then after you reglue it, then glue a corner block inside and it should never fail again


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## red (Sep 30, 2008)

I agree that the wood failed, not the biscuit. I think reglueing it and adding a pocket screw or two will give it another life. Red


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## GeorgeC (Jul 30, 2008)

skymaster said:


> Biscuit is doin fine :}:} Da Oak failed, that said from pic that joint can be repaired, all pcs seem to be there Tbond2 the critter, clamp it and it should be ok. If nothing fits inside that pc, then after you reglue it, then glue a corner block inside and it should never fail again


Yes. I think that picture is a good testimonial for the effectiveness of biscuits. 

G


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## kentuckytwostep (Nov 20, 2008)

It appears that the is no (or very little) glue on the actual butt joint. If it was glued and clamped sufficiently there would be wood splinters (from the board on the left) still attached to the end of the board (on the right).

It looks repairable though, use pocket holes.


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## johnjf0622 (Feb 8, 2008)

I would think that the end grain possibly failed when the biscuit swelled putting stress on the end grain. And as said already, glue failure. Kentucky is right there should be splinters. I also prefer dowels. just my opinion.


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## djonesax (Mar 3, 2008)

I agree that the wood failed BUT.... I believe the wood probably failed as a result of cutting the slot for the biscuit. As ch0mpie put it "the wood closest to the end grain whose fibers have been sheared by the biscuit slot" Still surprised it happened though.


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## clarionflyer (Apr 27, 2008)

I agree with nearly all of you. I could fix this joint (pocket holes and glue), and never see the difference. But that wouldn't be too enlightening. I also agree that dovetails would be the strongest replacement here. 
But since it's mine, I think I'll experiment a tad, and try box jointing the corners. I like the looks of it, and now I'm interested in the strength of boxes (just for giggles). I'll send more pics.
Thanks for the responses.
__
I used to feel that the glue would replace the strength lost in cross cutting the end grain of the biscuit joint (wood). Not so sure now. It seems the glue may have been a tad light on the ends, but I know the glue was thorough in the biscuit. Considering the load, it should have held together.

So, considering all this? I think I'll mostly use biscuits for alignment (adding just a bit of strength) to a joint. 
Just my opinions, lads. Happy woodworking.


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## mmtools (Aug 21, 2008)

I agree.. Pocket screw joint with a little glue would work best. The end grain on oak is inherently weak.


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## djonesax (Mar 3, 2008)

clarionflyer said:


> __
> I used to feel that the glue would replace the strength lost in cross cutting the end grain of the biscuit joint (wood). Not so sure now. It seems the glue may have been a tad light on the ends, but I know the glue was thorough in the biscuit. Considering the load, it should have held together.
> quote]
> 
> I was looking at the picture some more and got to thinking. I bet as the glue expanded the buscuit, it put stress on the end grain causing it to crack and become weak.


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## dbhost (Jan 28, 2008)

I think what you had happen here might just e a freak failure. Never had a biscuit joint fail yet. Not that I have done a lot, but still... The fibers of the oak SHOULD have held fine. Having said that, it looks plenty fixable...


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## JigStik (Jul 9, 2007)

It was the choice of joinery that was not correct. A biscuit that close to end grain, in that particular type of service was asking too much. Although the biscuit itself did not fail, who would expect a biscuit to break in half. The best choice would have been through dovetails, even one large through dovetail, splines, or even a finger joint. You need a lot of long grain in that application.


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