Unknown Accessory EMCO
Your missing some stuff but do a search for EMCO vertical mill/drill attachment.
That has brought quite a bit of curiosity to a close. Appears as if a pully attatches to the threaded stub, and a handle goes into the hole, and it gets mounted on a shaft, thats quite the funny system! Ha, makes you wonder how effective it was.
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Like an overbuilt jacobs chuck?
It’s a “milling” spindle for an Emco Unimat 3 with a fine adjustable feed in the side and a collet holder. You would mount this in a steel column that ist attached to the watchmaker lathe. Unscrew the collet part and by sticking metal rods into the holes and unscrew the collet holder (right hand). It uses a propriatary attachment system and the other parts that you may find should have the same threaded attachment.
AS in unscrew the silber collet holder from the black spindle.