You might want to explain the type of surface fininsh you need, which may or
may not be the same results as the type you might be anticipating (depending
upon numerous variables).

Variables.. type of metal, overall size of the workpiece, the type and
condition of the machine(s) being used/available, cutting tool (typically
referred to as bit) geometry and material, operator's skills, and also
speeds and feeds.
Also, using a cutting lubricant, which is nearly always a preference.

With the correct application of variables, the built-up-edge (and
cracking/chipping of the cutting edge) conditions should be completely
avoidable.

The usual rotary table designs are very slow, and unless it's motorized (and
built solidly enough to be used for feeding material while it's being
machined), turning it by hand will result in variations in speed of the
workpiece which will result in changes in the machined finish.

If the application demands that the finish of the surface has to be
precisely flat and exceptionally smooth, then cutting it with a cutting edge
might not be the correct application.
Precision grinding will produce much better finishes, so second or third
operations might be required to attain the required results.

Whether your available equipment can produce the fit and finish that you
actually require can't be anticipated by others without more information
from you.

WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html


"Michael Koblic" wrote in message
...
Just so I understand: There is a definite BUE range of speeds, you are OK
above or below it (as far as the BUE phenomenon)?
Would an alternative solution be to run a fly cutter over it on a rotary
table?
Thanks,

Michael Koblic,
Campbell River, BC

"Mark Rand" wrote in message
...

The specific problem tends to be that, if you are using carbide or HSS at
high
speed, you can get a beautiful finish on the outside. Swarf coming off
yellow
or blue (for carbide). At some point towards the centre the speed will
fall
into the region where the Built Up Edge phenomenon occurs. The surface
finish
will go to hell during this range. As the tool gets closer to the centre
the
finish will still be bad, because there is a rough gob of steel welded to
the
tip of the tool.

Running HSS below the BUE region all the way will avoid the problem, but
can
still benefit form changing the speed as the cut progresses if possible
e.g.
from maybe 50rpm at 5" to 250 at 1". This is easy if you have a variable
speed drive. It's a waste of time if you need to do belt changes.

Running carbide above the BUE region can get a bit scary towards the
centre of
the part :-)

PS. The best way to get a nice finish is to slap the part on the surface
grinder after facing BEG

Mark Rand
RTFM