On 2010-12-16, Chris Wilson wrote:
I need to make a fair number of 6 mm OD stainless steel pins to take 1 mm
OD R clips. I want to drill the rods near one end with a 1.5 mm hole for
the R clips. I have a Bridgeport universal mill

You have a *what*? I didn't think that Bridgeport ever made a
universal mill (X-axis table swivels). Perhaps you mean a *vertical*
mill?

and a decent drill press. I
have pin drill chucks to taske small drill bits. What's the best way to
drill say 50 of these pins with good efficiency and little chance of
breaking drill bits in them please? Best bits to use? Thanks.

The best way in my mind requires tools which you have not
listed. Don't you have a lathe? Ideally with collets to fit the 6mm
pins. Fairly high spindle speed suggest a smaller lathe, which probably
means 3C collets or even down to WW collets.

I'm not familiar with R clips, FWIW.

Even something like 150 SFM would take 9700 RPM, which is rather
high for either the mill or most drill presses, except for a sensitive
drill press.

And *which* stainless steel? Some are fairly easy to work,
others are quite nasty. Looking at an old Jorgensen steel
catalog/handbook, I see SFMs for Stainless steel running from 75 to 160.
For a couple of samples:

# SFM RPM
=======================
303 100 6468
304 75 4851
316 70 4527
416 160 10348

So -- can your mill or drill press get that kind of spindle
speed? How about half of that speed?

It really calls for a small lathe -- and likely something like a
Taig or Sherline might get the speeds right. And I know that the Taig
has a spindle available for WW series collets, which are commonly
available in metric sizes in 0.1 mm steps.

Good Luck,
DoN.

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