Thread: Wood Movement

Originally Posted by John Samuel

Pete,

I hear you. However, if I leave the rear joint in the web frame unglued with a small gap, do I then glue the rear section (blue in the pic) of the web frame to the panel/legs?

APPROACH ONE.
Attachment 292045

that is my preference

One more question ... If I make veneered MDF panels with (say) 45 mm stiles and rails rather than edge banding (which I dislike) is it OK to dado/biscuit and glue the web frames to this panel and glue up all the web frame joints; or do I still need to allow for movement?

MDF is stable
you can dado/biscuit, glue, screw web frames to an MDF panel

Originally Posted by John Samuel

Below is a day bed made recently. I now see that the 325 mm deep side and back panels are unable to expand where they are glued to the legs. I could, in the future, make the side panels (say) three separate pieces of timber with space between them, or I could make it with the frame and panel method. Any other ideas/suggestions?

the "proper" or traditional way is to form divided tenons on the ends of the panels. For the moment I can't recall the proper term, but think of a tenon in the shape of an E with very wide horizontal strokes -- the corresponding mortice would have three pockets, two of which would be oversize. Only the centre portion of the tenon is glued, the other two can them expand and contract in their "pockets"

Originally Posted by John Samuel

The only thing that surprises me a little about all these discussions is that one seems to need to allow for movement even when a frame and panel construction method is used for the sides of the cabinet. I thought that given the web frame was glued to the stiles only that it would not be necessary to allow for movement.

We live and learn.

strictly speaking this is true, but there are advantages of always using a similar construction in that you are less likely to forget and glue a M&T when you should leave it floating

also, the panel in a F&P construction is usually too thin to screw drawer runners to

Gentlemen,

Thank you one and all. All my questions have been answered.

You have once again demonstrated the value of the brains trust at this board.

Originally Posted by ian

the "proper" or traditional way is to form divided tenons on the ends of the panels. For the moment I can't recall the proper term, but think of a tenon in the shape of an E with very wide horizontal strokes -- the corresponding mortice would have three pockets, two of which would be oversize. Only the centre portion of the tenon is glued, the other two can them expand and contract in their "pockets"

Yes yes, a much simpler joint than my suggestion



Pete

Originally Posted by ian

the "proper" or traditional way is to form divided tenons on the ends of the panels. For the moment I can't recall the proper term, but think of a tenon in the shape of an E with very wide horizontal strokes -- the corresponding mortice would have three pockets, two of which would be oversize. Only the centre portion of the tenon is glued, the other two can them expand and contract in their "pockets"

Yes yes, a much simpler joint than my suggestion



Pete

Originally Posted by John Samuel

....the end of the frame has grain running in the same direction as the drawer runners. It seems to me that this should give the same problems as a frame glued around a timber panel, but so far it has not. Can anyone help me understand why? Am I doing something foolish here? Is there a better way?

"So far " is the key phrase! You are begging for trouble gluing anything across a substantial amount of cross-grain. I know mortise & tenon joins involve cross-grain glueing, but the distances involved are usually short, and so don't develop quite the same amount of stress as a runner glued across a wide panel. So far, either there has not been a deep-enough moisture cycle to rip them apart, or the glue you used is still flexible enough to accommodate the stresses, but eventually, in 99% of cases, it will give up & let go sometime down the track.

In my own early days & ignorance of sound woodworking principles, I did all kinds of "wrong" things, and it seemed like I'd gotten away with it, too, for a few years, but one by one my sins came back to haunt me. In one case, it was more than 10 years after I'd built a pine cupboard before the mouldings I'd glued gross-grain along the top & sides let go, but let go they did. (The time taken might have had something to do with the sheer amount of glue I used back then... ).

I apologise if I was one of the people who have brought this to your attention, John (but I'm sure it was the other Ian ). We have caused you sleepless nights waiting for the sounds of rending wood & drawers collapsing in the dark! It's like the bloke I read about in the paper on the weekend. He asked for a test, then when he got a diagnosis of possible cancer, he wished he'd never asked for the test in the first place! At least a busted drawer runner is relatively easy to fix, & will have an excellent prognosis if done right.

Cheers,

Originally Posted by IanW

I apologise if I was one of the people who have brought this to your attention, John (but I'm sure it was the other Ian ). We have caused you sleepless nights waiting for the sounds of rending wood & drawers collapsing in the dark!
Cheers,

Ian,

No need to apologise ... grateful for the advice. The good news is that my furniture is either in my house or my kid's houses, and they got theirs for free. So, let them stay awake at night waiting for that sickening, tearing sound. I will sleep like an innocent.

If and when they fail, I will fix or replace them (built properly this time). In the meantime, I am having fun in my workshop.

It seems that I may have had dumb luck on my side. Most of my stuff was Wau beech in the beginning, because I was getting it very cheap. Then I moved on, mostly to cedar and NG Rosewood. These timbers are low shrinkage and fairly stable in service ... but dumb luck only extends so far ...

I've just had a +12 year old box lid split. I thought I'd get away with gluing the carcass across the grain because it's only narrow, ~150 mm, and I did, until now.
I think it's the only one I've done like that - I hope.

Originally Posted by AlexS

I've just had a +12 year old box lid split. I thought I'd get away with gluing the carcass across the grain because it's only narrow, ~150 mm, and I did, until now.
I think it's the only one I've done like that - I hope.

Awww ... guys ...

Until recently I was blissful in my ignorance. Now I know better. I promise I'll be a good cabinetmaker in future. But can we please stop with the horror stories? I have pieces 10 years old that have survived just fine ... so far ... (no, Ian, don't say it). I intend to ignore the fact that they are all at risk and to pretend that they are fine until that tearing sound happens.

Elephant? What elephant?

Don't worry John you be right

Originally Posted by Wongo

Don't worry John you be right

I surely will, Wongo. You really must tell me the origin of your nick one day ... I am a bit fascinated.

Cheerio!

Originally Posted by ian

also, the panel in a F&P construction is usually too thin to screw drawer runners to

I very much doubt that, Ian. Not my frames. I am a world class over-engineering expert!

My biggest disappointment over the last week is discovering that a unit that could hold an elephant's weight is in danger of self-destructing.

Bother, spit and darn!

Here is a wild untested and unsupported theory developed in my never-ending pursuit of over-engineering.

About 30 years ago I built a timber double carport. I wanted a clear span, and because I was as poor as a church mouse, needed to be able to make it myself at low cost. I needed two beams to span the 6.5 M carport, the rear beam was supported by a post, but I wanted no posts in the middle or front of the carport.

I decided to make laminated beams out of 3X2 inch oregon pine. The beams were curved. I made them by putting a 60 mm block in the middle, bending the first member over this and nailing it to the carport floor at the ends. Then I built it up to about 10-12 inches thick using 308 glue and screws. Then I put some bolts through the lot (told you I was good at over-engineering). I made the first beam and was delighted. You could park a battleship on that beam and it would barely flex.

Sadly, I used all the 308 glue on one beam, and it was as dear as poison ... so much so I could not afford to buy any more. I stumbled around the hardware store until the owner decided to give me some advice. He recommended another glue he assured me would do the job admirably, but at a fraction of the cost.

I made the beam ... with an early version of what we now call construction adhesive ... and discovered that this glue moves ... a lot! Under a very light roof, that beam flattened ... lost it's 60 mm curve entirely ... stopped only when the bolts hit the sides of the holes and locked everything into place. Drove past it recently. It's still there and still flat.

So, here is the question. If instead of leaving some joints without any glue at all we were to use construction adhesive on these joints, would the glue be flexible enough to move with the humidity? Would it move enough? Would it harden with time and lose its flexibility? I note that some manufacturers claim their product remains flexible ... but how flexible?

OK guys ... be honest ... but be gentle. I'm feeling a little sensitive after having all my wood movement sins exposed to the entire universe and I am just bouncing ideas around at this stage.

You are stuck in a sticky situation

If you were born before glue was invented then your gonna have many sleepless nights. Listen to moi, there are other ways to hold 2 pieces of wood together. Glue is not the only answer.

One of my kids just suggested that you were correct; that I was indeed born before glue was invented.

I intend to scratch his name off the escutcheon with a rusty nail ... immediately after I write him out of my will and burn all the photos of him. That's almost as bad as my daughter, who, in Year 1, asked me if I knew Jesus.

Wongo, you are, of course, quite correct. For instance, I recall helping my dad make furniture held together with wedges when I was a kid. Flat packs were around long before Ikea got into the game.

Pourtant, allez-vous élaborer?

au revoir!