I've read several posts lately about wood movement and thought I would post this up in case anyone didn't know about it. It's near and dear to my heart because I work to stupidly tight tolerances when I make my puzzles, and my work gets shipped all over the world (i.e. different climates).
Compression shrinkage occurs when wood tries to expand but is constrained by its surroundings (i.e. locked into a puzzle or a drawer inside a frame). When that happens the wood absorbs moisture but cannot expand. The cells then take on an oval shape, and when the wood dries, it is permanently smaller then before it tried to expand. So, if you make something a little too tight when it's dry and you find it has locked up in humid weather, best thing to do is store it somewhere for a few dry/humid cycles. It might surprise you by working itself out via compression shrinkage!
As far as movement in general, I keep a close eye on humidity in my shop and adjust my work accordingly. If it's super humid I'll make the puzzle as tight as possible while still being assemblable. If it's dry I'll make sure key joints or places where pieces will interact have a few extra thousandths to move around. I recommend putting a decent hygrometer in your shop and getting into the habit of checking it if you do any precision work. I bought mine at a cigar shop for $20 and calibrated it using a ziploc bag and some damp salt in a soda pop cap.
Compression shrinkage occurs when wood tries to expand but is constrained by its surroundings (i.e. locked into a puzzle or a drawer inside a frame). When that happens the wood absorbs moisture but cannot expand. The cells then take on an oval shape, and when the wood dries, it is permanently smaller then before it tried to expand. So, if you make something a little too tight when it's dry and you find it has locked up in humid weather, best thing to do is store it somewhere for a few dry/humid cycles. It might surprise you by working itself out via compression shrinkage!
As far as movement in general, I keep a close eye on humidity in my shop and adjust my work accordingly. If it's super humid I'll make the puzzle as tight as possible while still being assemblable. If it's dry I'll make sure key joints or places where pieces will interact have a few extra thousandths to move around. I recommend putting a decent hygrometer in your shop and getting into the habit of checking it if you do any precision work. I bought mine at a cigar shop for $20 and calibrated it using a ziploc bag and some damp salt in a soda pop cap.
