pine cupping

[speed]

hi everyone

im having a little problem with some pine lids for toyboxes ive glued up

first one i did 2 weeks ago, it was warm in the shop when glueing up (using d4 pva and biscuits) then took them in the house to dry sanded and fitted and it has been fine until the last day or 2 its started to curl.

the second one i left in the shop for 2 nights and fetched it in the house, overnight it cupped bad

i am using 4x1 and glueing 4 together x1m so only a smallish panel of 1mx400 and i am alternating the groth rings up and down

any suggestions to stop this hapening? use smaller timbers maybe 2x1, i used the same glue up method for the sides and bottom and so far they have been fine but are joind together

im running out of time to sort these as its christmas in a week

 

[MARK.B.]

You could try braces fitted to the underside of the lids that may help to keep things flat.

 

[speed]

i forgot to add that i have 2 x 3x1 under glued and screwed

 

[MARK.B.]

Ahh well then on to plan B

 

[mseries]

Perhaps a breadboard end ?

 

[Sheffield Tony]

i forgot to add that i have 2 x 3x1 under glued and screwed

Don't glue them. Just screws, not overtightened, with all but the middle one through slotted holes. So that the top can slide as it expands/contracts, but is held flat. This is how old drawing boards were kept flat.