How to prevent / remove twisting in laminated boards

[Taziman]

Hi all,

Just a quick question. Yesterday I helped my son make a laminated chopping board for mum. The board is made out of Jarrah and Cyprus pine. See pic

168031

When we constructed it, made sure we flipped each alternate piece of the Jarrah to try and avoid cupping. Once dried it was cut to length, then run through a thicknesseer to bring it down to flat and the right profile. Was sanded and then rubbed with stainless steel wool and orange oil to finish it. Came up beaut apart form a slight twist.

When you lay it on a flat surface you can slightly rock it on two opposite corners. I would have expected it to warp side to side, thats why the grain was alternated. I have tried to remove the twist by placing a length of timber diagonally underneath the board and then camping down on the two "high" corners to try and reverse the twist.. Left it like that for a few hours. Undid the clamps and it was dead flat, until it sprung back an hour or so latter.

Is there any way to remove the twist?? should I have left it in the clamps over night to remove the twist??

Are there any tricks to avoid this in the future ? As I really like the finished look (and so did the mother-in-law) :roll:

Cheers and Beers

Taz

[Harry72]

As its a chopping board it will spend its life exposed to moisture so warpage is inevatable, if its not going to be a user you could machine it flat.

[groeneaj]

Hey mate,

I think I can help. I have made a couple of chopping boards and understand what you're saying. Below is what I'd to to fix it.

- remember that a thickneser parallels the opposite face. So if you put it through with the opposite face twisted or bowed, it will come out twisted and bowed. You got to ensure it's flat by running it over a jointer, or using hand planes then put it through the thicknesser.

- you can fix it now by removing the finish and use a hand plane to flatten the uneven side.

I made mum a board and when I put it on her kitchen bench, it wasnt flat and it wobbled. I went to Bunnings and got 4 rubber feet and attached it to the bottom of the board. Depending on which way it's cupped this should work ( it did for me).

Good luck

Andy

[Arron]

I'd leave that one for a while. You might find that the twist disappears, or gets worse, or goes in some other direction. Either way, it makes repairing it quickly a bad move. The rubber feet idea is a good one - not aesthetically ideal but it will disguise the problem while you wait.

To avoid it in future, cut the timber roughly to size, then leave it in your shed for a few weeks before joining it up and planing it off. Any twist that is going to happen will have happened by then and you can rectify any winding rather then carrying it through to the finished job.

cheers
Arron

[Taziman]

Well guys thanks for that. I think I have solved it..

We glued up another laminated board, for the MIL, and once dried, son sanded all the glue runs off the underside and got it fairly level.

We then took it inside and laid it on the kitchen bench. Damn got a twist in it. Then I remembered a trick, well not at trick, but a technique, that I was taught when I did my apprenticeship. It was how to get a piece of metal dead flat, by using a "truing table" and some blue ink called from memory :Prushan Blue".

What ya did is got the truing table (a dead flat machined steel table) and covered it in this blue ink. Then you got the piece of steel that you were attempting to hand tool flat, and rubbed the surface over the flat steel table with the blue on it. When you looked at the face of the piece that you were trying to hand finish, you could see all the high spots as they had blue ink on them. Then you went away and filed that area until all the blue was gone then repeated the process until it was dead flat.

So to improvise I got some blue line marking chalk and covered the kitchen bench with it.( Lucky SHMBO was not home :U ) and then rubbed the face of the board over it. Turned it over, now we could see where it was high. So out to the workshop and got the son busy sanding the high spots.

After a couple of goes got it fairly flat, so then ran the board through the thicknesser, with the now flat surface to the base. After bringing it down to size re-checked it on the bench and now we have a dead flat board with no twist,, :2tsup:

All the son could say is "Told ya I was good"... grrr damn smart ass .. :~

Cheers and Beers

Taz

[thompy]

it'll also work in reverse taz, like a panel beater. cover the item in the blue or guidecoat use a longer bit of straight and sand, the high spots will show as cleared wood, sand those till no more blue left. no need to use the flat. great improv though. glad you got it flat:2tsup:

Neal.