Great pic, Mick
Jed, I'm sure you know this, I just wasn't describing correctly. Say you have a dirty pc of wood to cut, say 90% of the circumference is dirty, you start the cut with a pulling chain with the nose of bar in the clean 10% of the log, then, keeping the nose buried, the saw teeth only hit clean wood, when they encounter dirt it is at the end of their pass thru the log, they hit dirt and blow it out into space with the chips. If the teeth hit dirt last, instead of first which would drag the dirt thru the cut and dull the teeth instantly, you can cut all day in dirty conditions and still be basically razor sharp at end of day. There are different ways to do the cut, with a pushing chain for example, but the idea remanins the same, don't drag dirt thru the kerf. I'm sure you know this already but hey maybe somebody else can get something from this.