"Steve B" fired this volley in
:

So, Lloyd, is this a diamond blade, or just a blade with some sort of
coating or do the notches do the cutting? Might this be something the
Borg would stock? It sounds like what I need.

No, just a disk of HSS. The notches simply provide room so as the edge
expands, the blade doesn't cup or warp when it gets hot. It cuts purely
by friction heating getting the work metal hot enough to scrape away.
They count on the red-heat hardness of high-speed steel to make it
survive the red-heat softness of the sheet metal you're cutting.

You have to run them fast (rotation rate), and apply pretty good pressure
to get them to cut... no diddling in the work.

The Borg would normally stock them. Sometimes even my local ACE does.
Sears always did, too.

LLoyd