Reaction Wood

[Michael O'Sullivan]

I had my first brush with reaction wood today.

I jointed and planed a 5" wide piece of 4/4 walnut that I wanted to rip into 1" strips to use in some x-mas cutting boards. The wood milled fine and the first rip was perfect. On the second rip, 1/3 of the way in (about a foot), I started to feel a lot of resistance, so I hit the stop button with my trusty thigh. At first, I thought one of my featherboards was set wrong, but then I saw that the wood had completely closed up behind the splitter. Since the first piece had gone fine, I thought it might just be a funky spot in the wood, so I flipped the board and tried to do it from the other side. Same thing happened.

At that point I cut the wood up by hand for firewood.

[Fred Voorhees]

Michael, if it closed up behind the splitter, wouldn't the splitter have prevented it from pinching the blade? Afterall, that is what a splitter is there for. Curious.

[Blake Holton]

This type of behavior is more commonly cause by stresses developed during drying and generally referred to as case hardening. Reaction wood (or more specifically tension wood in hardwoods) can cause what you experienced, and will also likely cause other problems, especially in finishing.

Glad you were safe.

Blake

[Michael O'Sullivan]

Michael, if it closed up behind the splitter, wouldn't the splitter have prevented it from pinching the blade? Afterall, that is what a splitter is there for. Curious.

I think it was closing up both on and behind the splitter. The splitter definitely helped avoid a kickback. I am sure that if I had applied enough force, I could have pushed the piece through, but that seemed inadvisable.

[John Coloccia]

When I get wood like this, I'll cut it fat on the bandsaw, and then treat it like a rough board (jointer, planar etc). The bandsaw's really great for safely dealing with difficult wood like this. Unless I'm cold, and then it ends up in the fireplace