Revolving Tail Stock Chuck or Rotating Tail Stock Chuck

[metric_taper]

duplicate message, somethings .......

[metric_taper]

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Just used a Jacobs chuck with a 3/8-24 thread and some bearings along with
a MT2 taper blank that I made a year or so ago and some mystery metal.
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Cheers, JR

I'm curious how good the runout of the 3 jaw drill chuck is?

I like the idea of the 3 bearings that will average out the radial play to near zero, as well support the cantilever forces from the 3 jaw chuck.

[jjr2001]

I'm curious how good the runout of the 3 jaw drill chuck is?

I like the idea of the 3 bearings that will average out the radial play to near zero, as well support the cantilever forces from the 3 jaw chuck.

Well my assembly runs just a bit better than .001" . However after trying 4 small chucks (3 jacobs ) I was able to get the total runout to about .003". These economy chucks are not so great.

The jacobs chucks are the lower quality designed for small hand drills and such. So I ordered a 7BA and that hopefully will be much better. The worst one had .008" runout with a dowel pin in the jaws.

[jjr2001]

Well I do have a traveling steady but it is a bit large but I guess I could have tried it....I have pictures of a "micro traveling steady" that is on my build list.

The thing is that what Marv said, "Shafts with turned down sections on the ends of the parent stock can be turned without benefit of TS support by feeding just a small bit of the parent out of the collet, turning it to size, then feeding a bit more out, turning, etc." was the answer I needed.

I used a 4 jaw chuck and just re-centered the square stock after each new stick out.
Thanks again Marv. Your process worked very well and I now have my stem for the steam chest. Yippie.

Here are a few pics with the two pieces of "practice metal" and one good part.

Cheers, JR

[mklotz]

I'm very pleased it worked for you. Be sure to favor us with some stills and video of the engine after it's completed. It looks like it will be a real winner.