Frank Warner wrote:
I'm a part-time knifemaker with a mini mill. Mostly I use it for
drilling & tapping but occasionally need to ruin, er, machine a piece
with its regular milling capabilities. This can involve end cutting or
side cutting.

Over the years I've collected a variety of end mills, mostly from sets,
all center cutting, 2-flute and 4-flute (I understand the difference),
single end and double end. Must have 2 or 3 dozen of these in different
sizes, all dull.

In fact, they seem to go dull incredibly fast, although they cut fine
when brand new. Might be my technique, might be the mini mill (not
rigid enough), might be I'm not holding my mouth right. Might also be
because they are the cheapest end mills available so they can be sold
in sets for $35 or so.

I use M-42 end mills now, and haven't bought any plain HSS in years.
The additional price is very little, the greater wear resistance is
remarkable. For 1/8" size I use solid carbide, I can get these for $3-4
on eBay. The no-name HSS Chinese stuff is junk.

Especially on stainless, don't make very shallow cuts or allow the
cutter to progress too slowly across the part. Either causes work
hardeneing, and the workpiece becomes harder than the tool. That's when
the burnout of the cutter happens. You have to keep up an aggressive
feed to prevent that.

Jon