Thread: Table Construction

Originally Posted by EagerBeaver71

Was he on Meth?

Teaches at one of our finest schools.

Did a quick google and the first article I found supports this:

Wood Movement

1/4 inch for every 12 ~ 1.66%

Your maths sux
1 in 48 will be a whisker over 2%.

Thats a septic site and they’re talking about shrinkage from green.
We have much greater humidity variation than they mention.
Ive made stuff with drawers in fully seasoned red cedar in the ACT and been unable to open the drawers back in Sydney.
Just to derail things further I turned a thin wall Blackwood bowl a few weeks back.
Turned a jamb Chuck today to clean up its bum.
It was 8mm out of round in a bit over 130mm diameter.
Squeezed into a jamb Chuck no probs.
Thats why patternfakirs laminate round stuff out of segments.
Trains would look funny with that amount of run out on their wheels.
H.

Originally Posted by Damienol

Teaches at one of our finest schools.

Did a quick google and the first article I found supports this:

Wood Movement

1/4 inch for every 12 ~ 1.66%

Are you saying for every metre wood moves 10-20mm?

That's wet just sawn from the log boards to dry boards.
The link is also saying 1/4 inch for every 12" on dry wood. You can see that sort of movement in things like unsealed drawer bottoms that are nailed in up at the back of the drawer. The front shrinks back out of the drawer front slot.
You wont see 1/4" of movement per 12" on a Kiln dried Oak table top or other sealed furniture sections unless its neglected and left in the wrong conditions for finished furniture.

Originally Posted by auscab

That's wet just sawn from the log boards to dry boards.
The links is also saying 1/4 inch for every 12" on dry wood. You can see that sort of movement in things like unsealed drawer bottoms that are nailed in up at the back of the drawer. The front shrinks back out of the drawer front slot.
You wont see 1/4" of movement per 12" on a Kiln dried Oak table top or other sealed furniture sections unless its neglected and left in the wrong conditions for finished furniture.

As in storage, in shipping containers & the like. Over the years I've had a few requests for assistance from acquaintances who have transferred and have had furniture in storage for a prolonged period. Many of the removalists now use shipping containers for longer term storage, the better ones store the containers out of the sun.

Originally Posted by Damienol

I was taught 1 - 2% which would translate to 10 - 20mm

Originally Posted by EagerBeaver71

Was he on Meth?

So on cocaine, then: meths is too far down market.

Thanks for clarifying that Rob. I thought Damienol was referring to KD wood, maybe he was I don't know but 10-20mm seemed very extreme for KD sealed wood hence my reaction.

There are various tools on the web that permit an estimation of wood movement. Some are more sophisticated than others. Have a look at these results.

Wood is natures elastic band. It will stretch to breaking point and shrink to oblivion given the right/wrong conditions. Clearout mentions Canberra. My blood runs cold. I remember trying to get some sort of normality into moisture content of timber destined for the new parliament house. Bloody nightmare.
Back to the real world. The table has no stretchers other than the top itself. Hence the top becomes structural and relies on the secure connection between leg frame and timber to minimise racking hence screw tightness is important. As the top has alread been called into service as a structural member, take it one step further, let it become the cross brace and cut the existing metal cross braces through at the centre. Screw the top securely to the two newly created tabs and the timber can swell and shrink to its heart's content.
Poxy design for legs IMHO.

Originally Posted by rustynail

Poxy design for legs IMHO.

I agree, the design of those are awful.

Just cutting the top bits of metal would work for expansion but not contraction (shrinkage)
Removind a few inches would.
Possibly also remove the majority of the bottom connection as in steel of that gauge the top will be pretty immovable.

Re the big house in Canberra the front information desk was made by a well respected mob of joiners here in Sinny.
About 10 years after it opened we were in there with reals from os who wanted to check out my efforts and the top of the desk had about 10mm wide splits in a few places.
It had virtually torn itself apart.

My Jarrah cab was ok.
The chairs were ok in the small batch productions but the mass produces ones where the Parliament House Authority did some cost saving were all failing thanks to the use of dowel joints rather than m & t as I’d prototyped for Aldo.
H.

Dead right Henry. I should have been more specific. I was thinking of a section being removed from the top braces, not just a single saw cut.
The Big House was definitly an exercise in futility. I have never worked on a job to match it for stupid.

Simple solution is to add a timber spacer between the table top and the legs. Screw & glue the spacer to the table top, then screw the legs to the spacer.