While my thoughts on flattening wood may eventually be formalised in a philosophical treaty on the place of man in nature (low), just some quick thoughts today.
I buy all wood at 1 1/4″ and generally need it between 3/4 and 3/8. It is what it is, and I’m getting used to dimensioning. I have found that about 70% of the wood I use, of several different types, re-warps after flattening. To avoid the heartache of getting close to finished width then having to plane way more off to deal with re-warping, I’ve slowed the process.
A few variables should be noted that affect the wood. Everything I can buy is being stored in open air warehouses. No climate control. Being right on the Caribbean humidity is high. Always. Forever. The end of the world will come and it will still be 85% humidity here.
Additionally, I’m not entirely sure how this wood was ever dried in the first place. With my remedial Spanish I know it’s kiln dried, but that only means so much.
Lastly, my “workshop” is the converted maid’s quarters built by the owners of our house. We have no maid to quarter, and so I get it. No climate control, really. A dehumidifier helps keep things around 50% humidity.
It’s an understatement that moisture is a problem. (sounds like the start of an adult diaper commercial)
Case in point, the small board above was flat yesterday. Birthed from a warped board, it has returned to form with the penciled corners marking the high spots. This board is headed to 1/2 inch width, with a bit more than a 1/4 to go.
I’ve started to leave the boards some time to get it out of their system. It’s showing some promise. I’ll flatten one side doing as little work as possible to do so. I then take some big bites out of the other side with a scrub plane. Then it sits getting the best airflow it can in my shop.
After a few days, I’ll check and fix the flat side, then take a few more bites from the other. Once the flat side has held flat for a few days, I’ll do the finally dimensioning work. I have two pieces holding after using this approach.
I’ve also taken a note from jointing to flattening faces. I find it tedious to slowly plane down high spots, and I’ve started to create a hollow as I cross plane the wood. The cross grain planing is pretty reliable to give me a flat(ish) board from side to side, and the hollow works between each end. Once I’ve carved a belly, I then mark the high spots and bring them down.
I don’t know if that explanation, or the technique, make sense, but it appears to be working. Wrote more than I intended…