On 2010-05-03, Ignoramus4389 wrote:
These are pretty small, they are the size of a quarter, roughly.

http://igor.chudov.com/tmp/kaiser.jpg

Hmm ... they look like screw-on insert heads for boring bars to
me.

Ones designed to bore to the bottom of a blind hole, if you have
CNC or some other way to reliably stop the travel at the same point
every pass.

Looks as though you have at least three sizes there --
determined by the offset from the shank which would be a continuation of
the cylindrical part.

Perhaps the hole is designed for flowing coolant through a
hollow boring bar and to the insert.

Any clue what thread is in the cylindrical end?

I would kind of like having those. They look a reasonable size
for my 12x24" lathe.

Enjoy,
DoN.

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