Two weakened spots - the holes - flex, and the part in contact at max
deflection would be where the burns are?
"Andy Dingley" wrote in message
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http://codesmiths.com/dingbat/photos/sawblade.jpg
But why should the overheating be confined to two opposed spots,
rather than a ring ? Is there some mounting-induced warp that I've
not noticed ? Runout (by eye) seems negligible.