I did something stpuid thoday. Story:
I was fixing my chair because A) I broke it by sitting in it and tilting it back, and 2) it was too tall for my desk and prolonged sitting at my desk hurt my back.
So, I put it all back together and made my marks at 2 inches to cut the bottoms of the legs. I started the first cut. It went smoothly, but slowly (it's a very hard wood, this chair--I figured that out tryng to put screws in it); I could smell that the wood was getting burnt. Then the saw (jigsaw) flipped out. I did not realize that the problem was being caused by the guide plate thing coming loose. The blade looked like it had a bend in it, and I thought that might be the problem.
Somehow, the connection between the smell of burnt wood and a really flippin' hot saw blade did not click in my head (really stupid, I know). I began too run my thumb and index finger along the blade to make sure it was straight. I didn't get very far, however. Soon I was jumping up and down, shaking my hand and yelling expletives.
Not one to leave a job unfinished, I made myself an ice pack and finished the cuts and cleaned up while holding a bag of ice in my left hand. Ironically, the sawing with the bag of ice in my hand went much more smoothly.
On the positive side, my chair works again, and it's at exactly the right height for my desk. And I'm going to have a really sweet scar on my finger of the profile of a jigsaw blade. You can even see the teeth. The thumb isn't bad. It hardly hurts anymore.
Remember kids: if you smell burt wood, don't touch the saw blade.