Thread: Timber Movement Red Gum

I'd be doing as your supplier sugests or you will be back every 6 months trying to get the thing flat.
A few friends have done as suggested with the slots and a few years on have no problems in both tables and benches.
All the best
Kevin

Thanks Kevin.

If I cut as suggested that leaves about 12mm of wood to hold it together. I think the cuts will achieve a required weakening of the slab so that it will be more easily be held flat. Could I rather than making cuts the entire length break each longitudinal into say 4. I would do this to provide several full thickness sections. My concern is if I don't do that it may break in handling. I suppose an alternative would be several transverse bracing pieces of wood.

At 650 wide you should not have to cut any slots in the underside - which is a very debateble approach at best - especially at 75% of depth which will weaken the overall integrity of the piece to an irrepairable degree. Resulting in cracking down the weakest point.
Your timber MC should determine how the timber reacts when the amient room tempaerature reacts with it.
On a 45 - 50 mm slab around 12% mc will keep it fairly stable - if your slab is not near this MC then be very wary of doing anything with it untill it is dried down a bit .

I have just dropped in to this forum - I have been making furniture for 25 years ( Gawd..!)
Hope you dont mind my reply - but I know a bit about slabs and stuff like that.
www.nannupfurnituregallery.com.au

Phully

Originally Posted by Phully

At 650 wide you should not have to cut any slots in the underside - which is a very debateble approach at best - especially at 75% of depth which will weaken the overall integrity of the piece to an irrepairable degree. Resulting in cracking down the weakest point.
Your timber MC should determine how the timber reacts when the amient room tempaerature reacts with it.
On a 45 - 50 mm slab around 12% mc will keep it fairly stable - if your slab is not near this MC then be very wary of doing anything with it untill it is dried down a bit .

I have just dropped in to this forum - I have been making furniture for 25 years ( Gawd..!)
Hope you dont mind my reply - but I know a bit about slabs and stuff like that.
www.nannupfurnituregallery.com.au

Phully

Spot on the money!!
If it"s a little high in moisture content, and you put cut's under the slab, after a while little cracks will apear at the top as the cuts from under the slab will kept going!
Have done lots of redgum bench tops. and if the slab is at the right mc you will have no trouble
Cheer's

Thanks Phully and GumRed.

The red gum slab will be 45mm thick and 12% mc also it will be finished with polyurethane. The saw slots worry me and I glad of your advice. They were advised by the timber merchant. I'm in Canberra you know the place where there are lots of galahs, some even wear suits and try to boss the rest of us around!

But I digress it is a fairly dry place about 450 to 600mm of rain and 90 Km from the coast. Does this change your advice? I am new to this but fairly good with my hands having been a sheet metal tradesman for 15 years but spent the last 30 years in IT (programmer/analyst). This brings me to the point that I do not feel that confident at making breadboards for it. Since the underside is not seen I am thinking of using sloted steel angle instead. Do either of you see a problem with that?

Mornin .

The really weird thing about timber is that it will do what it will do when it wants to . .. or not . .!
You could plop the slab down and just let it sit there and nothing untoward will happen to it - maybe . .!
Or you could do every thing that every expert woody tells you to do with it - and it will go all over the place . . . or not . . .!

Feeling more confident. . .?
Not trying to put you off - but generally if the peice is fairly stable, the ambient room temp is generally consistent and it is installed well - you should not have any issues with it.

Timber expands and contracts with varying conditions - constraining the ends ( Breadboards , metal etc.) should done with care - keeping a small allowance for this movement.
As attatching the top - use Z clips or similar - small metal brackets that fit into a slot in cabinet carcase and screw to the underside of the top that allow movement in the top.

You should do just fine with it - the thing about doing this lark is that it is always different even when it is the same . . .

And with those words of wisdum - I am off into the village to vote - then open the Gallery, bash a Jarrah bedroom together, go to an Election Party tonight, Sleep in my own showroom tonight instead of driving home ... .

Phully

Welcome Phully. Your & Gumred's advice is absolutely spot on. It will move, make allowance for it, don't waste your time trying to prevent it. If it's been dried properly to 12% you shouldn't have too many problems.

Thanks guys for your advice. I take that it will move and I need to make sure this is allowed for. So hold it flat but allow it to move across the grain. I will let let you know how it goes but it will be a while.

I agree with the guys above but just leave ample room for it to wander around a bit, it will settle down a bit in about, ohh,,,, maybe 100 years or so but even then it will still move I have never put cuts on the back of anything.

Claw Hamma thanks and it is good to know it will settle down after a 100 years. My slotted steel has slots of 30mm so will allow +- 15mm. I suppose if this does not work it always can be converted into an ashtray

Hi all, the man who kd's my timber and particualy red gum says that it must be dried to 10% or it will move. So far the kd slabs and timber that i have supplied to furniture makers have had no problems. Not so for timber only dried to 12% !!