I was cutting a straight line in some 3/4" ply with my bandsaw yesterday, when it began to make some thumping noises from inside. I finished the cut I was making, but came back to the saw later and made another small cut, when the machine thumped a couple more times, then jammed, and the fuse blew. SO, I quit for the night, and came back to it today. I took the covers off, looked around for anything that could have caused the saw to jam without finding anything.
Next, I tried to move the wheels by hand and found them very stiff. I was able to rotate them backwards, however and in a while that freed up the wheels to where I could run the saw without any thumping. As I have taken off the table and the covers, I didn't try to cut anything. The thumping stopped after I removed the lower blade guide, and one of the guide blocks looked pretty beat up.I've turned the blocks around, but I haven't reinstalled the guide, for reasons I will go into below.I vacuumed out any sawdust and crap that was lying around in the saw case, and ran the saw for a few secods to make sure it is running like a new saw at the moment. There is no apparent damage to either of my blades, BTW, in spite of the condition of the block. I am pretty sure I reset the blocks, and certain that I adjusted the lower guide when I installed the 3/8" blade. I was using a 3/16" yesterday and I don't think I moved it when I put the 3/16" blade in.
So, I am wondering if any part of that could have caused the thumping that I heard, or been related to the reason the saw jammed.
Some more details. The lower guide block, when I set up the 3/8" blade a year ago, only just reached the back of the blade and it was as far forward as it would go. I adjusted the blade on the upper wheel and came up with a compromise between having the blade run between the blocks, and cutting at a 45º angle because of the blade drift. The upper guide is OK for position and gap. When I installed the 3/16" blade, the blade actually sat forward of the lower guide, and I couldn't move it, so I left it alone. It has done a fair bit of cutting with this blade since I put it in so I didn't worry much.
Next, if you look at the photos below, you will see that the blade runs about the centre of the upper wheel, but within ¼" of the front of the lower wheel. With the 3/8" blade in place, the blade was almost on the edge of the lower wheel. This will be an issue if I try to put a ½" blade on it, and I want to do some resawing. So, what do I need to adjust, and how, to get the blade in the right position on the lower wheel?
Thank you in advance for your experience, perspicacity and erudition.