Butt Joint strength

OOHHHH Charlie beeeee......

Where are you?

;^)

Robert

snipped-for-privacy@gmail.com wrote: | The project I'm working on requires a butt joint that will undergo | a little stress. I'm obviously going the glue the length of the | joint, but I'd like to reinforce it with a)screws, b)dowels, or | c)biscuits. Anyone have an opinion as to which of these 3 would add | the most strength to the joint?

How many opinions can you stand? :-D

For me, the answer would depend on the stresses involved and what the cosmetic requirements are. I'm prone to use pocket screw joinery when I can - and M&T (sometimes pegged) when I can't.

Worse still, if I feel particularly AR about racking, I use a joint like the one pictured at the link below.

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

RE: Subject

Couple of layers of double bias glass and some epoxy.

Lew

Of the 3 choices, B.

If you go to a little more trouble you could do lap joints and strengthen the joint considerably.

Does it have to be butt or can it be a lap joint? Or can you cut the pieces staggered (like mirrored L's) so at least some portion of the joint it grain to grain?

I might have the wrong mental picture but how about tongue and groove?

Max

Of those choices, dowels unquestionably.

Or a scarf.

Square dowels, aka false tenons.

Butt joints are the weakest. Consider a scarf, finger or lap joint.

To answer your question where the butt joint is not subject to stress and blended for cosmetic effect the screw and dowel construction are the most effective. Where the joint is subjected to minimum to stronger stress, as stated before, "Consider a scarf, finger or lap joint". If you are dealing with oily wood like teak even two part epoxy will not adhere good you have to add mechanical devices like screws or equivalent.

Weld it, make sure to use stainless welding rod so it won't rust.

Thanks for the responses. I'm leaning towards dowels. To explain the project further, it's a fold over leg for a Murphy bed. As such, the leg itself (and the joint) is situated in the middle of the second piece which negates the possibility of using a scarf or half-lap joint. A stopped dado is a possibility, as long as I increase that dimension of the foot to compensate for the depth of the dado.

-Bill

I use dowels for virtually everything since I got a dowelmax jig. It doesn't have the production speed of a domino, but it secures the joint in all directions (not just two dimensions) and it doesn't require a $300 vacuum to use it. :-)

Bob

"A little stress" can be defined a number of ways..

Are we talking "shear stress" on a joint or "sag stress" from a bookcase ?

There are big differences between a chair and a table. Both get stress but you can guess which one receives the very most.

What are you build> The project I'm working on requires a butt joint that will undergo a little

We're talking shear stress, as the joint involves the foot underneath a murphy bed. The foot folds out from the top of the bed on a pivoting board. The joint in question is between the foot and the pivot board. The foot meets in the middle of the board, which eliminates a scarf or half lap joint. I'm leaning towards dowels as a strenghthener. I don't expect a whole lot of stress on the board, but I'd rather be safe than sorry.

-Bill