Someone is offering me a lot of appx. 300 lbs of used HSS endmills,
which are neatly sorted by size and need resharpening, for $75.
Let's say that I had an end mill sharpener like a Darex V90 or
whatever. Realistically, how long does it take to resharpen an end
mill (I would hire someone) and how much can I get per dozen of
"professionally" sharpened end mills, say in 1/4" size.
For the hobbyist they may have a value but a commercial shop would
probably have no use for them because of them being undersized from the
sharpening. Unless you can hold the size to within a tenth or two you
must reprogram the cutter comp for each end mill as compared to using
new end mills that are right on size.
The small 1/4 in end mills are not worth that much. Larger ones over
3/4 inch start to become economical to sharpen because of the higher
However, endmill diameter is not so important when used on manual milling
machines. More important to users like myself is the
material they are made of. I will resharpen cobalt hss alloy (M35/M42) and
throw the rest away, including carbide.
We figure the cost of tooling into every job and the saving usually aren't
worth the chance of ruining or reworking a part. I can't remember using an
end mill larger than 1/2", anything larger is indexable. They used to be
expensive and resharpening them was common. No more! But, if I "fell" into
a good sharpener, I'd do them for in-house use. I'd say used, sharpened end
mills @1/4" are worth maybe $10/dz.
Thanks, nice and solid number, something to work with. I would be
unlikely to do anything re: those used endmills. Sweeping floors at
Burger King would probably be more profitable. I could buy and scrap
them for a quick buck though.
If you can't make more money metalworking, versus sharpening metalworking
tools, then you're in the wrong line of work altogether. I don't mean
grinding a custom tool for a certain job, but doing it in bulk like you
Ignoramus6607 fired this volley in
First off, Ig, the 1/4" mills won't be 1/4" once sharpened, unless you're
only touching up the ends.
My guess is that used endmills _from_someone_else_, regardless of
condition, are almost worthless commercially, but might have some decent
value (say 40% of new) to hobbyists. Most shops willing to use re-
sharpened mills are having their own done. About the only way to tell if
a mill has been properly re-ground is to cut with it, unless you have the
optical stuff and the knowlege to inspect them.
While your question is more one of how can you make a buck off 300
lbs. of dull end mills, I for one will choose a reground end mill most
of the time. I have several reasons for this.
If I am milling on the edge of a piece of material it makes no
difference to me if the end mill is .005 undersize.
If I am milling a pocket or milling a surface being a little smaller
makes no difference either.
If I am milling a slot, an end mill tends to walk a bit so the slot
becomes a little bit wider, an undersize end mill will often allow me
to take a larger cut and keep the slot from widening too much. Also,
when I finish the slot to size, I only have one side rubbing, so it is
easier to get a better finish and predict the behavior of the cutter.
So unless the price of a new one is more than sharpening go for the
regrind. Usually however the tool grinding shop will beat replacement
Iggy, you might find a sharpener in your area that will either take
the dull ones off your hands with no effort or give you a deal on bulk
sharpening. I worked for a tool and die maker that had a fixture to
dress the end but usually he would just collect a dozen before he
would drop them off at the sharpener. Of course the economics may
have changed since then, but I suspect that a good quality end mill is
most always worth sharpening.
If you are running a long job and using an M42 or carbide endmill and
have a company that resharpens on a cnc grinder and will recoat the tin
on them you can save half the cost of new ones but they all have to be
the exact same diameter and length when ground or you have made yourself
You've had quite a few good pro and con replies so far, mostly "con".
I don't do any end-mill sharpening for myself (not qualified!!). On
the other hand, 75 bucks for 400 pounds sounds tempting, even if you
only sorted out 100 good ones. And if there is any of it in the
batch, carbide scrap is going for about $6.50 per pound
One question I would be asking before you consider anything else, is
what quantity of the end mills are "plain", versus those with corner
radius or ball-noses and other special shapes or those that may be
broken, any of which may not be "doable" to sharpen on the Darex.
A friend of mine in tool & die the has a nice Cincinnati Universal T&C
grinder with an air-bearing end-mill holder. He will sharpen larger
ones for his shop, say over 3/4", or down to 1/2" if they are special
like really long... (read expensive)... and then just changes the tool
size description in the tool CNC library/changer, and that way it
doesn't change "offsets" (which have a slightly different CNC
programming purpose). They don't diddle with sharpening standard
smaller stuff, and make the special small stuff with a Deckel SO to
suit the job, mostly for draft on carbon for EDM.
The issue I see is that if you use an edge finder or a dro, you've got more
math to do. It's too easy to screw it up. But, resharpened mill certainly
have their place and value, just not so much in a production or precision
situation. What's the cost of a part that needs to be fixed or pitched?
Maybe I'm just a little bit weird, but I actually LIKE when an endmill
is just a little undersize....
....as an example, if I am using a 3/8" endmill and the print is
actually calling for a 3/16" corner radius, if I just use the 3/8", I
may end up with chatter in the corner....
...but if I use a resharpened 3/8....it'll likely be around .360" and
all I need to do is change the tool diameter in the tool setup and I'm
That gives me the strength and chip load of a 3/8 while being
undersize just enough to generate the radius rather than forming it.
And yes, I'm talking about in a commercial setting.
The only real drawback to it is that if there was any coating...TiN,
TiAlN, whathaveyou...it's largely ineffective.
[ ... ]
And -- if it is a three-flute or a five-flute end mill -- how do
you measure the diameter?
Yes -- there are special V-anvil micrometers for such
measurements, one for the three-flute and one for the five-flute. Do
*you* have them? (I do -- but I collect tools, so I perhaps don't
But these special micrometers are expensive too -- especially if
you need to purchase them new. :-) (Unless you need the three-flute and
the five-flute versions to measure ground cylindrical surfaces for lobes
taking them off truly cylindrical. A standard micrometer won't see
these particular errors.
Of course --you could skip the edge finder and find your zero
with the old cigarette wrapping paper trick instead, which would include
the change in diameter in the setting -- for that *one* edge. :-)
I cut a lot of keyways and do them in on pass. A resharpened end mill
makes a project out of it.
If you know how much was taken off the endmill when it was reground you
can easily program for the smaller diameter but then if you happen to
have a new endmill in the holder... whoops. By the way you can get
regrounds recoated from some of the larger resharpen places.
When I used to have to use regrinds with odd numbered flutes, I'd clamp
the shank in a V-block on the granite table, put an indicator on the OD
of the shank, then pick up the reground edge with the indicator which
would give me the difference in the radius. Not a problem if you didn't
need .001" accuracy. If you did, use a new end mill.
Small printed circuit drills and mills...spots and such - are often
sharpened and left to be sold for nothing. New is fast and cheap (more or less).
Often only a tip is broken - so the sides are not ground. Just regrind
the end of the endmill.
Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
"Our Republic and the Press will Rise or Fall Together": Joseph Pulitzer
TSRA: Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Originator & Charter Founder
IHMSA and NRA Metallic Silhouette maker & member. http://lufk> >>> Someone is offering me a lot of appx. 300 lbs of used HSS endmills,
All of that may be fine...to a point...
....if it's being done on a manual machine, I"ll give you the new
mill/cut to size...
...you said that in a commercial setting, that it won't work to use
resharps...or words to that effect...
...and I will still say that ALL it takes in a commercial setting is
to measure the end mill and put that size in your tool set up and
you're done...I do it every day, all day long.
I would NEVER dream of pulling up an old program and putting in tools
that I haven't measured and calibrated...anyone that does is not only
asking for scrap, but begging for it.
I'll continue to use resharps for where they make sense....and new for
where resharps aren't gonna work.
there is a time and a place for both....the key is to know which is