Rotary Table Adapter to Mount 3/4-16 Lathe Chucks

I wanted a way to mount some of my lathe chucks to the little rotary table I picked up from Harbor Freight. My smallest lathe is a Taig, which has a nose spindle that is threaded 3/4-16. I have purchased or built adapters to use 3/4-16 stuff on my Mini-Lathe as well as my bigger lathe. So what I needed was an easy way to use these on the little rotary table.

I looked at clamping them to the table surface but getting them registered correctly would take too much time. So this is the solution I came up with. It is self registering with the table, and I can be moved from the mill to the lathe very easily.

My rotary table has a 7mm-1 thread under a 60 degree taper. The threads were rough and the taper not very smooth. So the first order of business is to clean them up. I centered the table under the mill spindle and ran a 7mm tap in to clean the threads up. Then used a 60 degree counter sink to clean up the taper.

For the adapter I chose to make it out of brass as I had it on hand.  The 7mm-1 threads were cut with a die held in the tailstock of the lathe, while the 3/4-16 threads were single pointed in the lathe. The small shoulder was left so I had something to hold the adapter in the lathe when I cut the 3/4-16 threads.

The dimensions are not critical as long as everything is aligned up with the taper. I used the nose of my Taig lathe as a guild for the dimensions. I made the 3/4-16 section longer than needed and once installed on the rotary table I took a measurement then back to the lathe to face it off the correct length to match the Tail nose threads. The chuck registers itself with the threaded adapter and sits firmly on the table surface.

To facilitate removing the adapter from the rotary table I used a slitting saw to cut a slot on across its face. I ground a very wide screwdriver out of a 3/4 inch spade wood bit, as you can see in the photo.

Installed in the rotary table the threads are a bit proud of the table surface. The taper keeps everything in alignment.

Taig 4 Jaw mounted on the Rotary Table. The chuck fits flush against the table surface.


All the components


While I was at it I made an 3/4-16 adapter to allow my small chucks and faceplates to be mounted directly to the mill table. Some times its nice to move something from the lathe to the mill and back again with out having to take it off the faceplate or out of the 4 jaw chuck.

From my original web pages December 9th 2009



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