Ball end mill cutters are generally side cutting, in that there is very
little/none cutting at the tip of the ball, unless you can source cutters
that are similar to split-point drills.
The same goes for countersink cutters.. they're just not as effective
without a properly sized hole to feed into.

After using the Dremel to center the divots at the ends of the pin,
proceeding with 2 split-point drills from opposite sides would likely be the
easiest approach.

Split-point drills begin to cut immediately upon contact with the workpiece,
whereas conventionally ground drills require feed pressure to force the
drill's web into the workpiece.

--
WB
..........


"Doug White" wrote in message
.. .

The double cutter approach seems to be the favorite. I had originally
been thinking of doing this in a mill, but upon further reflection, I
agree that a lathe is easier. I don't have to make a fixture for the
cutter on the "bottom" end, I can just put it in a collet. I also have
full visibility on both ends to see how things are progressing.

With all this in mind, I took a few measurements. The pin is smaller
than I thought, it's 6 mm in diameter. The dimple is too shallow to
allow using even a 90 degree countersink, so I'm left with drill bits or
end mills. I think a pair of 1/4" ball end mills might work, but
something smaller would be better. The swaging isn't perfectly
centered, and I want a little margin so I don't end up cutting into the
link. I only need to get the swaged part thin enough that I can easily
press out the pin without distorting the link.

A pair of 13/64" ball end mills should do it. That works out to 0.203",
compared to 0.236" for 6 mm.

Time to go shopping.

Doug White