pent up tension
Recently, while ripping a piece of zebra wood on the table saw, about 8 to 10 inches into the cut, I notice the wood was no longer gliding smoothly through the blade – in fact, it had almost come to a complete stop. This is a serous concern as one of the dangers of power tool woodworking is table saw kickback.
(If you feel like being grossed out, Google table saw injuries. 😦 ) Luckily, I was using the riving knife (a thin metal blade that sits behind the saw blade to keep the board from binding on the blade, throwing the work piece backwards into the wall (or you), or sucking your hand into the blade). I immediately stopped the cut (leaving the board where it was in the cut) and shut down the saw. When I pulled the board off the blade I noticed that the wood had clamped down on the blade and the riving knife. It seems that the wood had just enough tension in the board (that was now relieved by the cut) to close up the cut and clamp down on the saw blade and riving knife. I have never experienced this to this degree previously – even with all the wet, pressure treated pine I have cut (and that’s a lot (i.e. 1600 sq. ft. wood deck)). It was kind of scary and kind of strange – but a definite eye opener.