Does anybody know what this is?

[The Mighty Mutt]

I found this buried deep in a drawer in my lab. I've spoken to a few experienced optical people and they have no idea. I've even asked my dad (no optical experience but an accomplished mechanic, just incase it's not optically related at all). It's 6 inches long. One end looks like a handle should attach to it, like the handle for a rethreading tap. The other end is 1/2 inch long and the sides are sharp while the end is absolutely flat. Other than the black ring (which seems to have been made by a permanant marker), there are no other etchings or markings of any kind, not even a part number. Any ideas? I appologize for the very large photos, but I thought the extra detail would be helpful. Thanks for any thoughts
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[Chris Ryser]

That is a pin to push out rivets or screws of a certain size or rout a hole

[uncut]

I will venture an opinion that this is an accessory router for a drill(stand-type), or a groover, possibly for notches or slots in lenses. It probably inserts in substitution of the common.

[fjpod]

But if it were that, why does it have a black ring drawn around it?

When I first looked at it, it reminded me of two things: 1. a drill bit extension, and 2. a slit lamp focusing rod due to the flat end.
...but it doesn't look exactly like either of the two things I mentioned.

[DragonLensmanWV]

I definitely looks like a replaceable milling bit, but for which machine, I don't know. Maybe the ring was there to position it at a specific depth?

[harry a saake]

sure its not a bit to rifle a gun barrel

[shannon]

I'm going to go out on a limb here....it's a doohicky! Sorry, had to throw that one in.

[loose-screw]

I definitely looks like a replaceable milling bit, but for which machine, I don't know. Maybe the ring was there to position it at a specific depth?

Before I started working in optics I worked in a machine shop and I would agree with Dragon on this on. Milling bit but for what maybe a mini CNC machine LOL

[JERRY HUANG]

3 mm router bit!

[drk]

2. a slit lamp focusing rod due to the flat end.
...but it doesn't look exactly like either of the two things I mentioned.

First thing I thought of too, F

[Geirskogul]

Swarf bit for drilling/milling, could even be from an old edger.