The tee nut on the South Bend lathe came broken as seen below. One side was missing and the whole nut was twisted. This project records the effort to fabricate a new one.
The hole for the lantern tool post is tapered and the two dimensions at the ends of the hole are 0.938" and 1.188". Other dimensions are shown in the diagram above. The angle of the taper was calculated dividing the difference in radii (1/8") by the thickness of the tee nut (1/4") and then taking the arctan of this number giving 26°.
A piece of 1/4" X 1 1/4" stock was cut to 1 3/8" with a hacksaw. The edges were cleaned up on the mill. The part was then accurate aligned in a 4-jaw chuck in the Sherline lathe. Center drilling was followed by drilling through with a 1/4" bit. The hole was then opened up to 27/64" with a succession of drill bits. This was then bored to a diameter of 0.90". The headstock was offset to 26° and the boring was continued until the small diameter was 0.938" A little chamfering with a file and the part was complete!