I was planing a bunch of oak boards for a friend and we found some of the boards had bowed, no surprise.
My friend, a structural engineer, suggested we plane the concave side to the cutters as this might relieve the stress that caused the bowing. I was was a little skeptical but OK we'll try it. Most of the boards showed a marked improvement and some, a small improvement with a couple that didn't change much. The boards have now sat for a week and the big improvement ones have relaxed completely and the others not so much. The ones that didn't improve got worse.
All in all a surprising experiment. Has anyone else tried or seen this?
Before planning where the boards flattened on one face at the jointer?
It's not unusual for boards to bow during or after planning for various reasons. I'm just wondering if you jointed one side flat first or just ran the boards through the planer as is. Also, taking the thickness down on one side only can cause a problem.
bow- deflection of the flat face of the board along its length (bent like a bow)
crook- deflection along the edge
cup- distortion across the face (face not flat)
twist- board twists along the length
Because the radial shrinkage of a tree as it dries is about half the tangential, most boards are cupped more or less. Cupping can be minimized in commercial operations by drying tall heavy stacks of lumber that mashes most boards flat as they dry.
I have never see bow cured as described. Bow typically results from the lumber not stacked for drying perfectly flat. Once the bow is set in drying it is there forever in my experience.
This has been my experience as well. Having a board bow somewhat during planing is not uncommon but I had never tried this method before and they weren't my boards. The owner made the suggestion and I tried it. I kind of expected them to get worse. I really don't know if this was a one off on this lot of wood or if it will work to some extent with others. It's something to try the next time to see if repeats.
