Replies

1. 
   _mj_ | Nov 30, 2022 03:46pm | #1

   Internal stress released by the cut. Can be caused by how it was dried (Web search "case hardened lumber") or from where in the tree it came from (Web search "reaction wood"). Both are pretty common. If you've been woodworking for a while and just discovered it you've been lucky!

2. 
   MIKEALEE | Nov 30, 2022 03:51pm | #2

   This is very common. I believe it's caused by internal stress built up during drying. I've had both air-dried and kiln-dried wood do it.

   Good quality kiln-dried wood, where they take the time to dry it slowly, is less likely to do it but there are no guarantees.

   Mike

3. 
   john_c2 | Nov 30, 2022 06:06pm | #3

   What those guys said.

4. 
   AaronNashor | Nov 30, 2022 07:53pm | #4

   Thank you all for the quick replies!

5. 
   jharveyb | Nov 30, 2022 11:30pm | #5

   What I do when I want straight pieces is to mark the pieces with a pencil and rip the parts out about a 1/4" over-wide with a bandsaw, which doesn't mind the bow (especially safer than ripping bowing wood on the tablesaw.) I then joint one edge and rip a small amount of wood off the other edge. There is generally not enough wood removed for the piece to bow again; it did all or most of it when bandsawed.
   Don't even think of ripping a construction grade 2x4 down the middle with a tablesaw, unless you like lumber coming back at you at high speed. I always use a bandsaw for that.

6. 
   elmaduro | Dec 01, 2022 09:44am | #6

   When the cut starts to close up on itself, I’ll push one of these down in the out feed kerf to open it back up. A shim with a dowel drilled through ..

   
1. 
   pictakinman | Dec 02, 2022 12:57pm | #7

   Sounds dangerous if done while rip is in progress. Not sure I understand your procedure. A bandsaw is safer if the wood has tension. At any rate a splitter or riving knife will help prevent kick back on the tablesaw.