I know the answer is on this forum with all the knowledge on band saws I see. Well, I was cutting some useless scraps of wood down to fireplace size using a 1", 1.3 tpi old rusty blade on an LT-18. Stupid me, I forgot to tension it, so the scale read around 5mm (scale is in mm of blade width). Cutting small pieces went so well that I didn't even notice the problem. But when I tried to cut off a glued on 3/4 ply from 8/4 maple (a table sled I had given up on) the problem announced itself. About 2/3 of the way on the piece (12" into the cut), the blade started to spark like I had hit a screw buried in the wood. From there on the blade fluttered horribly and made the worse cut I have ever seen. When that piece was done, I checked the guides and noticed that the blade wasn't tensioned. I checked the blade and saw 2 teeth were missing, but I didn't think it would make a big deal on the cut and I was wearing my bullet proof full face PAPR helmet. So I tensioned the blade and tried to cut the other side of the sled maple/plywood to salvage the maple. Almost the same thing; less flutter, but absolutely terrible quality of cut, lots of sparks. I carefully examined the cut wood and I did not cut any metal buried in the wood.
So the questions. What happened? What broke off the two teeth? What created the sparks? Why does two missing teeth result in a terrible cut? What else probably happened that I am not thinking of?
James