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John

wrote:
On Sat, 02 Oct 2010 23:37:49 -0400,
wrote:

Ignoramus6607 wrote:
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.

i

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
replacement cost.

John

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
done.

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.

Luck

Mike

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.

John