Table top warp

[Damienol]

Hi WWF,

i have just finished building a farm table for my deck and had all sorts of warping issues with the top.

The table is made from reclaimed stairs that were approx. 1200x245x65. By the time i had cleaned them up and straightened they were abouy 1180x230x46.

The table top is 3530x1150x46 and is constructed in three parts. The two outside oarts are made by laminating 6 of the steps together to provide a 3530x460 piece. One step was gut in half so that i got overlap when laminating. The middle piece was made by laminating 3 lengths end to end.

The finally assemble involved the use of dominos and pocket hole screws. Due to weight issues this was not done until the table was in its final resting place.

The main issue I had was that one of the wider pieces warped in multiple directions, concave to the side and the top. The other pieces remianed fine.

when it came to assemble it was impossible to get a perfect butt joint rgardless of the clamping pressure involved. I know farm tables are suppose to have a rustic look however i was going for a pulstic (polished rustic) look and am somewhat disappointed that 6 weekends of work have resulted in upto a 2mm gap on the table top.

I did think about putting this on the jointer to get rid of the side concave however at ~ 70kh a length this was not feasible. The face concave I manage to reduce to an acceptable level via 10 screws per corner into the legs

Any suggestions on how I could avoid this in the future!

396333

[Kuffy]

It looks like a nice table even with the split join. You can make a feature out of the split by squirting some black polyurethane in and then levelling it back once it has dried.

To avoid such issues, you probably should have straightened the edge which had warped. To help avoid having timber warp so badly in the first place, you can machine the boards close to final dimension and then put them aside for a week or two to acclimatise. Then come back and machine to final dimension by only removing a mm or two instead of 19mm all at once.

[ian]

it's hard to tell from your picture, but when gluing the treads together, did you alternate the growth rings?

growth rings all running the same way can cause issues

[Damienol]

Thanks for the advice Kuffy.

unfortunately the final boards were too big for the jointer

[Damienol]

Thabks Ian, I forgot about the growth rings trick

[Bob38S]

Yes, always alternate the growth rings.

As an extra for this sort of join I use a blind spline. This consists of a routered groove which is stopped short of the ends of the join eg 25mm. Depending on the material, I go as deep as the router bit will allow. The full length of the grooves is made out of a strip of 4 or 6mm ply which is made so that you have it slightly undersized in the length and depth to stop any hydraulic action of the glue putting the joint under stress while drying. The thickness of the ply matches the thickness of the grooves to form a sliding fit. The glue I favour for this type of join is Titebond III and have not had any failures. When clamping, alternate your clamps top and bottom as you clamp it together. I also use a sacrifice piece of ply along each length of the edges to defend the edges of my table top to help spread the clamping force and to protect the finished edge from being dinged by the mouths of the clamps.

Just some thoughts you might like to try and or modify to suit your purpose.

[Damienol]

Thanks Bob

I did the ole clamp alternation trick and for the first week or so there was no warping, just seemed to happen the. Orning I wanted to put it alltogether.

I used dominos instead of the spline and pocket hole screws instead of glue as I need to be able to able to dissassemble to be able to move.

With regards to the growth rings I also remner reading an alternate view that state it was more important to match the boards astheticly then to worry about the grain direction. Clearly not the case for one of my boards

[Bob38S]

Thanks for the explanation.