On Thu, 29 Mar 2018 08:53:06 -0700, wrote:

On Tue, 27 Mar 2018 12:05:09 -0700, Bob La Londe
wrote:

A buddy of mine called me yesterday saying he was having some troubles
seating tools in his new bench top mill. I stopped by to see if I could
help and I found there appeared to be only a thin ring of contact
surface very near the large end of the taper on every tool and collet.
So little that tools tightened down HARD just fell right out when the
draw bar was loosened. Its supposed to be an R8 spindle and came with a
few R8 tools.

So how much contact surface should I expect to see between and R8
spindle and an R8 shank tool?

I have had one mill with an R8 spindle and if I had tightened a collet
into it as hard as I had to to tighten tools into his mill it would have
taken several hammer blows on the draw bar to knock them loose.

This is my buddy's second mill with an R8 spindle and tools he was
struggling with on this one seated easily and worked just fine on his
old one.

I wondered if maybe he got a spindle with an MT taper by mistake but my
uneducated finger says it feels like the wide taper angle of an R8, and
not the shallow taper angle of an MT. I do have some misc sizes of MT
taper tools for my lathe. I guess I could head over and see if they are
a better fit just to be safe.



Greetings Bob,
The machine spindle is not an R8 taper. The contact length should be
about .625" long for an R8 taper. It could be a #4 Morse taper. The
major diameter of a #4MT is almost exactly the same as an R8 taper
while the minor diameter is larger than the straight part of an R8
taper shank. So an R8 taper shank will fit into a #4MT hole. When an
R8 taper collet is put into the spindle does the small end rattle
around? It will in a #4MT. The spindle may also have some taper in
it that doesn't match any known taper. In any case your friend needs
to have the machine, or at least the quill assembly, replaced. Push a
clay plug into the spindle and use it to measure the angle of the
taper. Or use an indicator to measure the taper.
Eric

I agree.

Its either a #4 or a badly..badly cut R8


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