Do biscuits add strength? Solved!

[Essex Barn Workshop]

Third in a great You Tube glue myths series has just landed. Worth a look if, like me, you have a biscuit cutter.

 

[Doug B]

I was always told biscuits were for alignment not strength so no real surprise, It would have been far more interesting if he’d used dowels or even dominoes

 

[Essex Barn Workshop]

I was always told biscuits were for alignment not strength so no real surprise, It would have been far more interesting if he’d used dowels or even dominoes

I quite agree, and suspect that maybe he will go on to examine splines, dowels and dominoes.

 

[johnnyb]

surely the problem with joint failure(at least the type he's talking about) is the movement of the wood over several seasons. mitres in particular show big gaps ie the angle changes at the inside corner. so biscuits seem to stop immediate breaking.

 

[stuckinthemud]

I'm sorry, I can't resist, but, in my experience, they add inches to your waistline but don't necessarily increase your strength

 

[Jake]

I have not finished watching it but so far he's testing at exactly 90 degrees to any strength the biscuits are adding.

 

[Felipe]

I wish he tested similar to real usecase, torquing long pieces as in a table stretcher i.e.
that’s what matters to define the structural stability of your build.

 

[WillM]

Large size.

 

[Spectric]

There is a lot more to the strength of a joint than just what is used, ie biscuit, dowel or M&T. You have the actual type of wood or material, the application which will determine the type of forces the joint needs to withstand as a chair will be very different to a kitchen unit, so all methods will have their place somewhere and in my opinion biscuits are for alignment, the glue does the rest. When you fit a biscuit you are introducing a weak spot as you remove material from the workpiece, the question is does the biscuit compensate.

 

[DBT85]

Not sure there is anything new or controversial in the video.

If I had one it would be for alignment. I chose to just get the domino instead and I'm glad I did.

I was always told biscuits were for alignment not strength so no real surprise, It would have been far more interesting if he’d used dowels or even dominoes

There have been many over the years.

 

[pgrbff]

surely the problem with joint failure(at least the type he's talking about) is the movement of the wood over several seasons. mitres in particular show big gaps ie the angle changes at the inside corner. so biscuits seem to stop immediate breaking.

I have used biscuits in architraves around doors for years now and not a single one that I know of has opened up.

 

[Spectric]

I have used biscuits in architraves around doors for years now and not a single one that I know of has opened up.

Yes I have seen biscuits used by guys installing fancy trim work, for alignment and help hold it in place whilst glue dries. They do have a place, been around a long time.

 

[Doug B]

I have not finished watching it but so far he's testing at exactly 90 degrees to any strength the biscuits are adding.

This is true & possibly why he found the shearing in the biscuit.

 

[Phil Pascoe]

I use them for two reasons - 1/ for alignment, and 2/ to help stop a butt joint pulling apart. The way he was breaking those joints is largely irrelevant.

 

[Oakay]

Third in a great You Tube glue myths series has just landed. Worth a look if, like me, you have a biscuit cutter.

Not so great series of videos. I think some of the tests are unrealistic and cause 'followers' to misunderstand real-use structural situations and could make bad judgements in future as a result of that. There are details which make a difference, and I strongly disagree with end-grain jointing being weak as being a myth. Glue joints end to end should certainly NOT be relied upon for any length of time for any structural situation. Not every follower agrees with the conclusions if you read them, I am just flabbergasted that so many think he is a sort of genius and myth-buster. Even this biscuit joint themed video lacks some reality in practical use situations. Biscuits definitely have their place in the world of jointing, not just for alignment, but the devil is in the detail.

 

[Thingybob]

Sorry cant help it either but ask Peter Kay he will tell you use hobnobs they are tough you can dip em twice at least lol

 

[Oakay]

I use them for two reasons - 1/ for alignment, and 2/ to help stop a butt joint pulling apart. The way he was breaking those joints is largely irrelevant.

Another typical use of a biscuit will be to transfer the load on a shelf to a side.

 

[Phil Pascoe]

Not in my house it isn't.

 

[TheTiddles]

This guy again….

next up, do carrots really make you see in the dark? That other thing we all know but really, they don’t.

At least he’s stopped measuring force in kg

 

[Oakay]

Yes I have seen biscuits used by guys installing fancy trim work, for alignment and help hold it in place whilst glue dries. They do have a place, been around a long time.

Me too. Like me I am sure you only use well-seasoned timber. You can't really prevent a mitre-joint from opening if the wood needs to shrink, but if the glue to the biscuit is really good, it is possible to split the wood instead. When biscuit jointing thin timber or mdf I clamp over the biscuit itself if I can which vastly strengthens the joint. Tightness of joint and thin glue-lines add to strength immensely. The simplicity of the joint is marvellous, I wish they were available in miniature, with smaller saw blade but still with similar depth of cut for narrower joints.