Nope, not chainsaw. I've run my wm lt40 for close to 12 years and never seen or heard of this. I was sawing a 16 ft 24 inch knotty syp into 1X12. Suddenly got all the symptoms of a dull damaged blede, tooth marks, dives, climbs, etc. OK, I figured I just messed up and pushed the blade too long. Changed to a fresh pineywoods resharp, 1 board later, same thing. Stupidly mounted another blade, same result. Thinking hidden metal, employed mark 2 eyeball and a wand type metal detector, no hits. On blade number 4, I noticed some sparks and immediately stopped the blade. I had just sawn through one of many 2 inch sized knots with a strange looking center. Dug the knot out with a wood chisel, and found a marble sized ROCK in the center. Close inspection of previously sawn boards found several more of the same. Crushed granite of the type and size usually found in roadway paving. Not embedded in the bark, but 3 or 4 inches down inside the log, about 8 feet up from the butt. The customer graciously paid me for 6 messed up 1X12 boards and sharpening 4 blades, no idea how the rocks got there, although he did admit the log came from a tree beside a gravel driveway..Rocked bandsaw blades, whodda thunk....
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At least my rock (slag) was in a crotch. You can see that it killed the blade. :-\
When I was a kid working in a small 5 man circle mill, we were cutting trees harvested beside the rail track. One big sitka spruce had a shard of granite the size of a mans workboot about a foot inside of the log. Caused big damage, danger city....Apparently when they put the rail line in, blasting sent this piece of rock into a tree and it grew over it as the years went by. Perhaps your situation is similar??
30 - 40 years after WWII, European country sawmills had a lot of grenade and bomb shrapnel buried under years of tree growth.
Messed up a lot of saws.
My guess is that some time in the past some youngsters decided to throw some "rooster tails" on the driveway, and some gravel got thrown around. A few bits got caught in some knot holes or crotches.
Locally we have trees up in the National Park that have volcanic rocks embedded in them, from eruptions 100s of years ago.
Much more common are pebbles ground into the bark from dragging the logs. Before I cut into bark I walk beside the log checking for dirt, grit ,metal and yes pebbles. Frank C.
I have a very good customer that I saw for almost every year and the one thing that I have to keep reminding them of is, when you're skidding, pick up the front end of the log.
His logs are skidded down a road that has been built up with tailings from the zinc mine.
It doesn't take much of a hit to disable a blade!
I've sawn rocks in rootballs but never logs.
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Touching a Bushhog to the shoulder in a gravel driveway will salt the pine and cedar saplings with rock fragments. Regards, Clark
This is pretty weird. I have watched crows take rocks before. They also take nuts and drop them on hard surfaces. You have to wonder if birds, squirrels or something else stored them in cracks or were using them up in the tree. Probably not UFOs though.... :) :)
We have about decided it was probably a bush hog about 10 years ago. The county road was gravel then..Shore did mess up 4 blades. Lucky, I do my own set and sharpen...
About a month ago, I found a stone with my blade about the size of a golf ball :snowball: