using a steady rest

[lojo]

Does any body know of a good website or any advice for using a fixed steady rest. Bit of a problem remembering the correct facts about the use of steadies.
From my memory, if you are turning a long shaft with a damaged centre hole, you grab the shaft in the 4 jaw chuck by 1/2 an inch or so and roughly clock it.
You then bring the steady fingers up to the other end of the shaft and roughly clock that end. Back down to the chuck and clock again this time more closely, then the steady end again more accurately, repeat each end until you have the run-out within about .001" each end.This should have the shaft running true and parallel to the axis of the lathe.Does this sound about right? I'm more concerned about being parallel to the lathe bed.

[John Stevenson]

I use a steady rest a lot doing electric motor shafts.
Quickest way I have found to set one up is to measure the shaft where it's to be supported. In my case that is usually a known dimension like 25mm, 30mm, 1" etc
I chuck a piece of drill rod that size in the chuck sticking out about 1 1/2" and set the steady rest to run on this. I then remove the drill rod and store it away and move the steady rest down the bed to where it needs to be and fit the job in the chuck.

As I say most of my jobs are standard size and repetition so I have the setting bars.
If it's an odd sock size or you don't have setting bars then just turn a piece of scrap to to the size you need and use that to set to. At least turning in the chuck will ensure greater accuracy and concentricity.
Take longer to write about than to do.

John S.

[Mike Burdick]

Lojo,

Here is an excerpt from the US Army's Training Circular, TC9-524 Fundamentals of Machine Tools . In addition to John's post above, perhaps this may prove helpful as well.

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Setting up the Steady Rest

To setup the rest, first machine and polish the portion of the work that is to be used as the bearing surface. Clean the portion of the ways where the steady rest is to be mounted, place the steady rest on the ways and clamp loosely. Open the top of the steady rest and place the workpiece in the chuck with the bearing surface over the adjustable jaws. Clamp the steady rest securely to the ways. Close the top of the steady rest and adjust the jaws to the workpiece. There should be 0.001 inch clearance between the jaws and the workpiece. Tighten the locking screws on the adjustable jaws. Lubricate the bearing surface generously with a heavy oil before turning the lathe on. Proceed with the machining operation Continuously watch the bearing surface and the adjustable jaws to ensure a film of heavy oil is between them. As the machining operation continues, also check the bearing surface and adjustable jaws as when the workpiece heats up it will expand, closing the distance between the jaws and the workpiece.

Using Steady Rest with Headstock Center

When it is not possible to hold the work in the chuck, you can machine with one end supported by the headstock center and the other end supported by the steady rest. Use a leather strap or rawhide thong to tie the work to the driveplate and to prevent it from moving off the headstock center. Mount the work between centers and machine the bearing surface. Set up the steady rest. With the work mounted between the centers, tie the lathe dog, then remove the tailstock center and perform the necessary machining.
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Lojo, the circular in its entirety can be found at http://155.217.58.58/cgi-bin/atdl.dll/tc/9-524/toc.htm and is well worth reading - even if you are an expert.

Mike



[This message has been edited by Mike Burdick (edited 02-14-2004).]

[lojo]

thanks for that guys.

[metal mite]

lojo,

What that army manual dosen't tell you is if the steady isn't in line with the spindle the part will quickly walk out of the chuck and hit you in the head.

You're gonna have to indicate that polished spot true IN LINE WITH THE SPINDLE before you set the .001 gaps.

On a big job you may have to indicate the bar laying in the steady to get it true.

Have to indicate the top and side of the bar (pita) to do this.

May just be safer to make a plug like John says.

Saw a 4" dia x 100" shaft come out of a lathe once.
It took the top of the steady right clean off.
And to the brazing shop you go with the steady.

Lucky that guy (not me) didn't kill himself.

But do it your way.

mite

[irnsrgn]

lojo, I made this self centering steady rest so that I could quickly center drill a long shaft for using the tail stock, I also use it to line a long shaft up for the regular steady rest. It is not heavy enough to use for heavy turning, I sometimes use it along with the regular steady rest on shafting that is longer than my lathe bed to control vibration. it is accurate from 5/16 to 5 inch