Steady Rest

[one123]

How do you set-up a large shaft (about 3 to 5 inches in diameter and 10 to 18
inches long) with a rough surface to use with a steady-rest? The shaft will
be turned between centers and then one end would be put in a four-jaw chuck
and the other end supported by the steady-rest, so that the end could be
faced to length and then some other machining operations could be performed
on the end of the shaft. But, before you can turn the shaft between centers,
the end of the shaft must be supported by a steady-rest so that you can
center drill it. but before you can use a steady-rest, you need a machined
surface where you are going to place the steady-rest. Furthermore, how do you
indicate in the rough surfaced shaft before you center drill it? I am
confused. If you decide to use a cathead do you indicate the part or the
outer surface of the cathead itself to make sure the shaft is set-up
correctly in the lathe. Does anyone out there know what I should do?

[Al Flipo]

You will have to find the center with a center finder and drill the center in a drill press or with a hand drill to get started.

[Forrest Addy]

I assume you mean rough forgings or casting 3" to 5" dia and they're only 10 to 18" long? That's plenty stiff and stout to machine from the get-go. No cathead or steady rest required until you get round external features to use as journals and need the steady for the internal work.

NEVER use a three jaw on work like this. They have too feeble a grip.

4 jaw one end and dial it in with a piece of chalk if it's too rough for the indicator. Bang the other end in straight and center drill right through the scale (a touch with a 4" angle grinder to clean it up would be a kindess, though).

Start cutting. Stiff pieces like you describe really don't need a strady rest until you get the worst of the stock off. If you decide you're not getting a concentric clean-up, move the center drilled hole a bit with the end of a pointy carbide burr right in the machine. Immediately reinstall the center and turn a steady rest journal, install the steady on the journal, and re-tool the center hole for a good fit for the center. Remove the steady, apply the center, and procede.

There's a general lathe procedure for progressing rough stock to complex finished parts. It generally goes: rough the OD, rough the ID, stress relieve or heat-treat, semi-finish noting any stock deformation, make allowances is need be, finish all open dimension and clearance diameters, finish all fits, assembly features, and threads.

[Al Messer]

A cannon barrel? And you need the steady rest to bore it out?