Precise Centering tool for a four jaw chuck

A refinement of the tool is to make a large enough diameter pin and drill and ream a hole in the back (unpointed ) side of it to insert a smaller piece of round stock that has a center drilled end; a spring is inserted in the hole in the larger pointed pin, so that in use the spring is somewhat compressed, which eliminates the binding which occours when the part is moved in the chuck and also serves to push the part against the chuck jaws. I think that I got the first one that I have from someone who had worked at Mare Island Navy Yard, where they were made. I left it at my shop when I sold out and since made another for myself. A note; a small hole is cross drilled through the large part to relieve air pressure when inserting the smaller part.
 
A refinement to this device is to make it two parts, a larger diameter part with the point and a smaller part with the center drilled end; a hole is drilled and reamed in the back end of the larger (pointed) part to receive the smaller part and a spring, the spring tension eliminates binding when the chuck is adjusted and helps in keeping the part up against the chuck jaws. A small hole is cross drilled through the large part at the bottom of the reamed hole to relieve air pressure when inserting the smaller rod. I think this device was made at Mare Island Navy Yard originally.
 
How would that work, Woodchucker? There are two issues I was concerned about, how to position the part on center and then use that center reference for cutting tool placement. Please explain?
 
I also remember seeing this technique somewhere a while back. If I'm not mistaken, the one I saw had a ball (ball bearing) somewhere in the arrangement. It may have been one of Ca Lem's videos. Anyway - thanks for sharing!
 
Still uploading the video... don't be too hard on me..
This only solves the problem of centering. I was just showing another tool used in the old days. It works, but so does what you have done.
I have used an indicator on a center. And I have also used this a few times. The indicator is probably easier, as you get an idea how much to move 1/2 the reading. But in the old days, they did it by eye. And it was accurate. You are only looking for motion at the TS end with this.
 
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