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Bandsaw hitting a nail. Are there metal detectors that can penetrate deep through logs? It would be a great addition to this machine.
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Previously:
https://www.homemadetools.net/forum/...470#post122620
At that speed and size of blade I expect that was more than a mere nail...also that's a really expensive 'boinginginging'; I expect the blade is bent to the point of uselessness, and yes I seem to recall some sort of metal detector tool for this purpose.
I have heard stories from Dad about seeing what happens when a circular saw-mill hit a horseshoe inside a log. I guess teeth come off the blade and become deadly missiles.
I think it was more than a nail - you can see how the cut was pulled progressively to the left, and that would have increased forces on the blade, and pulled the blade away from its guides.
I don't think this was necessarily the saw hitting something in the log, I think it was a blade tracking issue leading to a crash. That's a twin vertical bandsaw (like this one), used to square off both sides of a log at the same time, and the right-side blade starts tracking to the center around the 3 second mark. I don't know about the first tiny spark, but I think the fireworks are the blade hitting the trough/feed chain under the log.
Here's one working properly:
https://youtu.be/aMLpfzFoAgs?t=65
it may have been a thick nail/ spike driven into tree by the eco warriors, who hate tree cutting,,they love doing things like this..
I think it's probably both of the mentioned scenarios. It looks like it nicked the blade at about 03 sec causing the blade to deflect as a result of the dulling caused by the nail (or whatever it was). The blade, when it tracked off, hit the conveyor chain as evidenced by the sparks come from underneath the log. Also notice the sparks from the left blade as the broken right blade contacts it. It would be easy enough to add metal detectors to the process to stop the conveyor before catastrophic blade damage occurs or a simple limit switch on the blade in case it deflected too far - simple. I would think a few sets of blades would pay for the equipment then you'd be money ahead - Labor + materials + downtime + not getting other things done while someone makes repairs = whole lotta cost!
My luck would be replacing both blades then the very next log having another nail!