South Bend 13" Lathe Spindle Indexing Attachment

I designed this indexing attachment around a 1977 South Bend 13" lathe with a 1-3/8" spindle bore.  The main mounting bracket attaches to the lathe via the knurled thumbscrew that holds the hinged gear train cover in place.  The index wheels are secured via an expansion arbor inserted in the spindle bore.  No alternation (i.e. drilling holes) of the lathe is required.

The expansion cone has a recess to accept the head of a ¼-20 x 2-1/2” bolt.  The bolt is secured to the cone with a hex nut on the opposite side of the cone.   The mating arbor knob uses a ¼-20 hex nut.  When I printed the knob, I paused the print when the recess for the hex nut was fully formed, inserted the nut, and the continued the print. This method encapsulates the nut inside the knob. 

The interchangeable index rings have double keyways, and are a snug fit on the expansion arbor.  I had considered adding set screws to secure the wheels, but the keyway design seems to be adequate to keep the rings in place.  I added the white text to the rings using my printer's slicer and a multi filament handler.  A sharpie marker would be just as effective and much less work.

The lock pin was made from 5/16” aluminum round stock.  I turned down a 1” section to 3/16” diameter and then parted off the rod, leaving a 5/16” diameter head approximately ¼” long.  The 5/16 head is a press fit into the lock pin cap, which is intended to make the pin easier to grip.  If you started with larger diameter round stock, the 3d printed cap could be eliminated.

To two parts of the main mounting bracket are assembled with ¼-20 x 5/8” bolts.  My design has recesses for square head nuts, but could be changed to hex recesses.

I printed in PLA and solid fill.