I picked up a few resharpened HSS end mills. I don't use them much, but
they were cheap enough that I grabbed them for some odd jobs. Since I
mostly CNC I mostly don't use them except mostly for screwing around and
learning stuff, but I've got a job in HDPE that would be perfect for
some I have that are unused. (Unuseed since regrinding.) The problem
is because they are resharpened the flute diameter is smaller than the
shank diameter, and I need just a little more reach than the flute
length. If I tried to use them for the bottom clean up where they are
needed they would rub higher up. Sure I can order some mills and have
them Tuesday, but I could sure use these today. Get the job done and
shipped so I can work on something else. I've got the machine
completely cleaned out and washed down with fresh coolant to try and
reduce metal contamination on the HDPE job. I don't want to put
anything else in the machine until the HDPE job is done. (The way the
customer is talking I might have to dedicate a machine to HDPE in the
future, but talk is cheap.)

Anyway, my thought was to stick the end mill in a collet in a spin
indexer and grind a relief above the flutes. Just enough to give me the
reach I need. Here is the problem. I'm kinda brand new to surface
grinding. So far the only thing I have successfully done with it was
flatten some vise jaws. I've tried a few other projects, but results
were mediocre.

Sure I free hand HSS lathe bits on the bench grinder all the time, but I
was wondering if there were any gotchas I am missing for a grind like
this. No I do not have a tool and cutter grinder. Its on the wish
list, but not yet.

Probably I'll have tried it by the time anybody replies (regrinds are
cheap), but I'd sure like to hear any productive thoughts you guys might
have on the subject.