So I am using proofgrade walnut hardwood that’s 1/8” thickness. I make these back panels for some art I create. I use DRAFT GRAPHIC settings for the PG materials and it takes about 21mins to engrave and cut a perfect 5.9” square around the words.
Every time I create these back panels the proofgrade materials curve up. Some are worse than others.
Also the proofgrade materials are perfectly flat prior to cutting so they are not curved before I work on them.
Does anybody know
why this is happening?
how to stop it?
how to “uncurve” the PG materials after the engrave?
A lot of times, engraving one side of wood will cause some warping as internal stresses on the material are now unbalanced, and also changes to environmental conditions (especially humidity) can cause the wood to expand and contract on the two sides separately.
You need to use pins or magnets, and get creative with their position and the placement of the etching and cut pattern.
You could try to use lots of magents around the cut line while you etch, with IGNORE the cut, then after the etching is done, move magnets so most are inside the border & even over the etching–careful not to move the material–then IGNORE the etching and run the cut.
Looking at your first photo I can see that you’ve painted only a section of the proofgrade, and presumably both front and back. It could be possible that the paint is allowing excess moisture in and as it dries it’s causing the warp.
Though I see it only doing it to your background layer, in which case I do have to agree with @evansd2, that wood is tricky and the environmental conditions can do a lot of funky things to thin materials.
With the number of air assist alerts that have been popping up largely due to the fan passing over the magnets, I think I’d be hesitant to use them if they were in the path.
When working with full wood you can take the warp out of it by getting it wet and letting it dry while held flat. Under those conditions the now dry wood will stay flat as long as it stays dry,
Proofgrade plywood and MDF will swell and fall apart so that has to be treated differently…
I wonder what would happen if the OP were to flip the panel and score/engrave some lines (or patterns) on back side to ‘re-balance’ the internal forces?
I imagine the direction of the lines would need to be parallel to the axis of curvature.
Might be worth a shot, but I’d use caution if it’s a structural element. Plywood like PG is mdf core, and it’s pretty thin. Engraving both sides will definitely weaken the material. Still, an interesting idea.
