I am anticipating an answer that I will not like, but anyway: I have a
number of carbide end mills (large number) and a lot of QC30 toolholders
that hold tools with a setscrew. Most of my endmills have no flats on
sides. If I hold one with a setscrew, is that adequate for real life
milling? I was able to mill machinable wax like that, but obviously
this is not a real test.
Not a prayer that a setscrew will hold without a flat. But you can grind your
own flats with a diamond wheel. They don't have to be pretty to work, but
should approximate a the slope-sided flat one sees on endmill bits.
Iggy, the "slope-sided" ones are variously called "safety flats". If a
flat is ground - well - _flat_, then when the setscrew loosens a bit, the
bit can creep free of the collet, unless the flat has a "stop" near the
butt of the bit.
When a taper is ground into a flat with the taper moving toward a larger
diameter closer to the butt of the bit, then any creep tends to snug up
against the setscrew again, lessening the chance that it will remove
itself. It also will make the bit loose in the Z-axis if the setscrew
creeps out. But that's better (for safety) than having the bit fly out
Such has long been used on woodworking equipment, although I seldom see
it on metalworking machinery.
If you have the tools, and are willing to carefully mark out your work,
you can cut a vee-groove "flat" to engage the setscrew. This will
essentially lock the bit in place, while minimizing the Z-axis looseness
if the setscrew backs up some.
Very, very doubtful. At least you don't have to worry about the carbide
shank getting mashed and never getting the tool out of the holder again,
but no, it will not hold the cutter securely. There is a REASON they
put Weldon flats on endmill shanks.
No -- you cannot expect to hold them with the setscrews in a QC
First, you will find that the end of those setscrews is flat,
with a bevel at the edge with is matched to the Weldon flat on the
endmills which fit it. This prevents the end mill from moving either in
Second -- normal cup-point setscrews depend on displacing part
of the shaft on which they are being tightened to get their grip. A
solid carbide end mill will *not* displace under any conceivable amount
of torque on the setscrew.
For those smooth-shanked solid carbide end mills, the ways to
hold them are:
1) Slightly undersized end mill holders without a setscrew,
designed to be heated (by a special bench tool) to expand and
drop in the end mill and then gripped by shrinking the holder.
I believe that the same heating would work to release the grip
on the end mill so you can replace it -- but I have never
actually seen or used one of these.
These smooth shanked end mills are made for use at very high
speeds, and the flat and setscrew would set it off balance
somewhat at those speeds.
2) A *good* collet type holder in the 30 taper shank. This means
one of the several double-angle type collets which close
parallel, not the R8 collets which have a tapered grip on
anything other than a prefect fit between the collet and the
3) Something which would work very well -- *if* and only if the
bottom end of the shank had the right thread is a Clarkson tool
holder in NMTB-30 taper (or whatever the precise taper and form
are for your spindle.) These combine the thread for firm
retention, a center in the holder to limit the rearward travel,
and a collet to hold the rest of the shank concentric. This is
a design which is apparently common in the UK. I have a couple
of the holders in 40-NTMB (from eBay), but no matching end mills
yet, and I am not certain that the threaded shanks are available
for solid carbide end mills.
To see images -- start with this google search:
Then click on each of the images to see more about them.
FYI, they use inductive heating both to expand the holder for receiving the
tool end, and to expand it again to release the tool. They come in two price
ranges: expensive, and outrageous. <g> The cheaper or smaller models often
don't do a good job of releasing HSS shanks, but all of the brand-name ones
work well with carbide.
These are for commercial work, and, as you say, they were designed for use
in high-speed spindles. However, companies that adopt them generally use
them for all of their mill tooling.
You can see good examples at the Biltz website. They also make many of those
that are house-branded by other tool companies. I'm drinking coffee at this
moment from a Biltz car cup. <g>
You've gotten lots of good advice, but to recap, if you have smooth-shank
carbide end mills, they were probably expected to be used in one of several
types of collet-type toolholders. You aren't likely to get a good grip with
setscrew toolholders. You may also have problems with them because they
don't center the tool very well, and carbide is brittle, not liking
However, there are Weldon-shank carbide endmills around, so it must work. As
others have said, you'll probably have to nick them to make a seat for the
setscrews. You might get away with a silicon carbide grinding wheel, but my
guess is that it will just frustrate you. Maybe a diamond tile wheel will do
it, if you have a tool that will hold those wheels.
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