Thread: Will the joint fail?

Mr dear Wongo,
while you were experimenting in your shed last night, way across the other side of Sydney, I was doing my endgrain to endgrain gluing. Below shows what was being glued, a piece of timber glued to the underside of a table surround. As I am about to shape the underside of the table surround, I needed the extra width. I didn't want to delve too much on what I was doing, as the technique used is in desperation, not in anyway traditional and very embarrassing.
Zelk

Hi Zelk,

Must be an easy life over there in Sydney. Here is Tassie life is so hard I don't know anyone who would wan to make it even harder by attempting that sort of joining process. What's the end game? what's it going to be made into? I'm inbtrigued.

Cheers Old Pete

Originally Posted by old pete

Hi Zelk,

Must be an easy life over there in Sydney. Here is Tassie life is so hard I don't know anyone who would wan to make it even harder by attempting that sort of joining process. What's the end game? what's it going to be made into? I'm inbtrigued.

Cheers Old Pete

Hi Old Pete,

I know it's puzzling, but the link in post 29 will give you some perspective.

Zelk

Zelk

I don't follow

Photo 1 look awfully like long grain to long grain, butting up against a bit of end grain

ergo a long grain to long grain glue up



ian

Originally Posted by ian

Zelk

I don't follow

Photo 1 look awfully like long grain to long grain, butting up against a bit of end grain

ergo a long grain to long grain glue up



ian

Ian,

I know, it's hard to make sense of it, as mentioned, in post 29 there is a link to explain it all.

Zelk

Zelk

I've looked at your link and I still don't follow.
I would describe what you are doing on the table as brick-laid-construction — small pieces of wood are glued together to form a 3-dimensional shape.
this is very common with turners, and as far as I know, glueing end grain to end grain is more a matter of convience during assembly than a necessity. The strength comes from the long grain to long grain bond between the brick-laid layers. Provided the end grain joint has no gaps, it needs no glue



ian

Originally Posted by ian

Zelk

I've looked at your link and I still don't follow.
I would describe what you are doing on the table as brick-laid-construction — small pieces of wood are glued together to form a 3-dimensional shape.
this is very common with turners, and as far as I know, glueing end grain to end grain is more a matter of convience during assembly than a necessity. The strength comes from the long grain to long grain bond between the brick-laid layers. Provided the end grain joint has no gaps, it needs no glue



ian

It may not be obvious from the initial photo but the piece that I am holding is the piece that was glued to the endgrain of the table edge surround. At that point there is no long grain to longrain gluing.

Zelk

Originally Posted by zelk

It may not be obvious from the initial photo but the piece that I am holding is the piece that was glued to the endgrain of the table edge surround. At that point there is no long grain to longrain gluing.

Zelk

now I get it, but unless that little bit of timber was the absolute last piece of wood in Sydney, I'd would have backed it up with brick-laid pieces from the underside of the top. The stuff stuck to the underside of the top and ultimately hidden by the piece you are holding could be any species you like — if you were worried about differential movement the "bricks" could be 2" long with 1/4 gaps between them

glueing unsupported onto the end grain is creating a significant lever which will likely fail the second or third time someone leans on it



ian

Originally Posted by ian

now I get it, but unless that little bit of timber was the absolute last piece of wood in Sydney, I'd would have backed it up with brick-laid pieces from the underside of the top. The stuff stuck to the underside of the top and ultimately hidden by the piece you are holding could be any species you like — if you were worried about differential movement the "bricks" could be 2" long with 1/4 gaps between them

glueing unsupported onto the end grain is creating a significant lever which will likely fail the second or third time someone leans on it



ian

Hi Ian,
That little bit of timber consists of eight smaller pieces.

You may have noticed the aluminium angle used for support the top, hopefully it will work and the small added piece will stay on.

The way I see it, the glue line is a barrier between the endgrain surfaces. Now if the barrier can expand and contract with the timber movement, the piece will stay there for ever providing there is no load.

What I realised later, was that the barrier mentioned is not the only one. As I have laminated the table surround, I have created continous barriers within the lamination, ie, between the layers. This table surround construction is inconsistent with the table top itself and there may also be possibility that the glue line holding the surround to the top may fail, in the distant future.

Wood turners may glue endgrain to endgrain, but the span is short.

Zelk

Will the joint fail?

Well, not just yet. The bond is as strong as the day I put pieces together.

See you again in 2 years time.

Originally Posted by Wongo

Will the joint fail?

Well, not just yet. The bond is as strong as the day I put pieces together.

See you again in 2 years time.

How do you know? The only way you could tell is by breaking it
Zelk

If you need to break it, it means the joint has not failed. The fact is the glue has been holding the 2 pieces together since day 1.

They are either together or seperated. It is as simple as that.

Since I made 4 of them so I suppose I can sacrifice 1 in the name of woodwork. Just for you Zelk.

Originally Posted by Wongo

Since I made 4 of them so I suppose I can sacrifice 1 in the name of woodwork. Just for you Zelk.

You're so sweet.