Revolving Tail Stock Chuck or Rotating Tail Stock Chuck

[mklotz]

Thanks for all the great info guys. I see that TM51 had a link where they are putting a large 3 or 4 jaw chuck on the tail stock.
Marv's solution is eye opening....Why did I not think of that....Pull out only the part that you need and then extend the blank
and continue keeping the part close to the collet or chuck.....I will try that method....

So far it is little piece of steel 2 and hobbiest 0.....Tomorrow I will try again.

I think my lathe tool bits were too dull. Sharpened all of them today and we should have a part by tomorrow night..

Cheers, JR

Oh, the model I am working on is Gerry's Beam engine. I posted a few of the parts completed so far here:
http://www.homemadetools.net/forum/g...m-engine-60782

The interesting part I am working on is the shaft for the steam chest valve.

Here's another approach to add to your list of ways to attack this job...

It's called a traveling steady. For large work this is a frame that is attached to the carriage and carries two adjustable arms that are set to keep the work from deflecting away from the tool. If you type "travelling steady" into Google Images, you'll get lots of pictures showing what they look like and how they are deployed in use.

The idea is that the travelling steady, as its name implies, travels with the tool, unlike the more common fixed steady which remains stationary. This means that the support of the work is always close to where the tool is cutting.

The conventional travelling steady is way too large and cumbersome to be used for tiny model engine work. Nevertheless, the idea is a good one and model engineers have come up with many variants that better suit their purposes.

One of these is a piece of stock with a hole the size of the parent stock drilled through it. This is clamped to the left side of the lathe tool with the stock to be cut passing through the hole. With the stock supported right next to where the cutting action is taking place deflection is vastly reduced.

Of course, this simple version has a major drawback. If you want to take a second pass on your cut, the hole in the steady will be too big. So this version is really only good for a cut that can be completed in one pass. Often, on tiny engine parts, this is possible.

When it isn't possible, tiny adjustable fingers [Sometimes a single adjustable finger with a birdmouth "V" groove is used.] are added to the steady so it can mimic the action of its bigger brother with the difference that it is attached to the tool or toolpost rather than the carriage. A Google search of the various fora that support model engine building will probably produce some designs (but it's probably more fun to design your own).

Keep this idea in your mental tool idea repository. Even if you don't need it at the moment, it may come in handy in the future.

[metric_taper]

duplicate message, somethings .......

[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.

[DIYer]

Thanks jjr2001! We've added your Rotating Tail Stock Chuck to our Machining category,
as well as to your builder page: jjr2001's Homemade Tools. Your receipt:

Rotating Tail Stock Chuck by jjr2001

tags: chuck, tailstock