Thread: Will the joint fail?

ive never been away... just keeping my mouth shut!

Originally Posted by zelk

Thank you for your replies.

Lets, for the moment, forget about where such a joint would be used. We all know that endgrain to endgrain is a weak attachment.

Lets assume that the pieces are glued to another without reinforcing, allowed to sit indoors as shown in photo 3, exposed to the natural variations in humidity and occasional sunlight and under no load for 5, 10, 20, 50 or even 100 years.

Keeping in mind that the timber will expand and contract, will the joint fail, as it is endgrain to endgrain?

Zelk

Depending on the glue and it's expected life, no IMO - if no loads other than expansion & contraction indoors. I have various simple end grain to end grain jointed pieces in my home that were joined using animal glues and are still together after more than 250 years including being used with small loads. But happy to wait around for 100 years to see how it goes . . . And if it is simply a theoretical question rather than a genuine need to sole a problem I'm outa here . . .

Originally Posted by ian

not having a go...
ian

Well yes you are . . . I know how to suck eggs too (well blow actually) and yes, screws into end grain do not hold as well as screws into other faces, but in the piece as described with no loads it would add considerable security. Depending on screw design/ type and method of use they can be very secure even into end grain (but depends how deep, timber characteristics, nature of loads and so on). This thread seems to be about theory and some sort of p**sing competition not practical application so I'm on me bike . . .

Its not entirely clear from the photos, but if the pieces are different lengths just make sure that the long and short bits don't line up, so the joint will match the rest of the joints in a brick wall pattern. If you do that, then it should hold for years, at least until some kids get hold of it, then all bets are off

As Bloss pointed out, I am more interested in the theory of endgrain to endgrain glueing, but it does concern a practical application.

I FEEL that gluing endgrain to endgrain will create a thin film of glue between the adjoining surfaces. One assumes that the glue will move with the expansion and contraction of timber, if it doesn't then there will be a shearing affect at some point in time.

I would imagine that some glues may be more successful than others, as Bloss hinted, hide glue may be preferable for this gluing application.

Feel free to trash this theory of mine.

Zelk

i read an article in AWR where the compared modern glues with other modern glues - the comeupance was that they are all pretty much the same. get the cheap crap and off you go... maybe a difference if u use a high oil timber and need to glue up with some foamy glue... otherwise meh....

I reckon your gunna get a failre if you glue end to end grain at some point - especially if you stress the joint somehow.

diff stresses in individual lengths within the joint (end to end grain that is) will eventually weaken the joint.

I tell ya - lap or loose tenon is the way to go. or as my first girlfriend ended up ; disappointed, broken and sore

Originally Posted by zelk

As Bloss pointed out, I am more interested in the theory of endgrain to endgrain glueing, but it does concern a practical application.

I FEEL that gluing endgrain to endgrain will create a thin film of glue between the adjoining surfaces. One assumes that the glue will move with the expansion and contraction of timber, if it doesn't then there will be a shearing affect at some point in time.

I would imagine that some glues may be more successful than others, as Bloss hinted, hide glue may be preferable for this gluing application.

Feel free to trash this theory of mine.

Zelk

More like some of the glue will migrate partway into the end of the vessells and then link with itself in vessells on the other side of the joint.

if this is theory, why not make a joint let it cure and then see how easy it is to break it.
do the same with a scarf, loose tennon, and half lap joints.


ian

Originally Posted by ian

More like some of the glue will migrate partway into the end of the vessells and then link with itself in vessells on the other side of the joint.

if this is theory, why not make a joint let it cure and then see how easy it is to break it.
do the same with a scarf, loose tennon, and half lap joints.


ian

Hi Ian,

As mentioned before, it's not about how to make the joint stronger using the methods you outlined, there is no load.

As someone has said sealing the endgrain before gluing will avoid starvation of glue at the joint surface and thereby improve the bond, but is that enough to ensure the life the bond, allowing for the natural movements in wood?

In this case, I'd like to get peoples view on whether the joint will fail irrespective of the type of glue used and secondly, will the choice of glue influence the life of the joint?

Zelk

Why don't you just tell us what you're trying to make? It would help A LOT with the discussion.

Originally Posted by zelk

Thank you for your replies.

Lets, for the moment, forget about where such a joint would be used. We all know that endgrain to endgrain is a weak attachment.

Lets assume that the pieces are glued to another without reinforcing, allowed to sit indoors as shown in photo 3, exposed to the natural variations in humidity and occasional sunlight and under no load for 5, 10, 20, 50 or even 100 years.

Keeping in mind that the timber will expand and contract, will the joint fail, as it is endgrain to endgrain?

Zelk

I vote no. It will not fail.

Originally Posted by Wongo

I vote no. It will not fail.

Thank you Wongo.

Zelk

I'm going to push this one more time, because the silly bugger might be going to do something like turn it. If this was true, it would be an explosion just looking for place to occur.

Zelk, what are you doing with the timber?

Originally Posted by Ron Dunn

I'm going to push this one more time, because the silly bugger might be going to do something like turn it. If this was true, it would be an explosion just looking for place to occur.

Zelk, what are you doing with the timber?

Not telling you. Thank you for considering my safety, you'll be happy to know that I"m not turning anything.

Ron, it's purely a theoretically matter. In one of my threads https://www.woodworkforums.com/showthread.php?t=79836&highlight=shaping, reluctantly, I need to build up timber in an area that requires endgrain to endgrain gluing. I have a few ways that I can reinforce the joint, but I was curious as to how long the 'load free' joint would survive without reinforcement. I wanted to go about finding this out in the least complicated way, I failed!


Zelk

Originally Posted by zelk

I wanted to go about finding this out in the least complicated way, I failed!

That ante the half of it. You have created a monster.