View Full Version : When is steady rest needed?

El Cazador
02-16-2008, 10:57 PM
Is there a generally accepted guide for the need to use a steady rest? I ask because the first thing I want to turn on the lathe I got a while back will be about 7-8" of mild steel of 1" dia. 3" in the middle will be 1", or close to it, and to each side about 2" of 3/4" dia.
Uh, yeah, I'm real new at this.
Redlands, CA

02-17-2008, 12:16 AM
I'm still learning myself Vic, and BTW, I'm also almost you're neighbor being up in Hesperia, :), but I think you'd be best to set up on a center in your tailstock for a long slender piece. If the piece was hollow on the end or somesuch where you couldn't get it on a center then you'd have to go to the steady.

I believe I've heard a good general rule is if you have more than 3 times the diameter of your piece sticking out in space you should be supported at the other end.


02-17-2008, 02:00 AM
I am no expert when it comes to turning but,
with only 7-8" you should be ok to center drill end and use your tailstock.
I have done similar sized pieces several times without using steady.
If the hole in your spindle is larger than 1 " you can chuck all but the end you are turning to further reduce flexing.
If you go much longer though you would probably need to use the steady.

02-17-2008, 10:10 AM
Here are some general tips for using the steady rest:
If your material is sticking out of the chuck more than 4 times it's diameter.
If you are unable to centerdrill the end for tailstock support.
If you are turning odd-shaped material and are unable to tailstock it.
If you need to faceoff the end of long material.
The steady rest is just another tool to help support the material.
Be creative.
Cazador, You might be better-off if you run that part between centers.

02-17-2008, 11:10 AM
I had always heard no more than 4x the diameter for a plain boring bar and 7x for carbide, so would think that KiddZima's 4x figure is spot on. (BTW, always loved the line from the ad: What's your sign? Stop!)

I would look at it as 4 diameters of unsupported length. I you have a 10" length of 1" rod, with 1" in the chuck, that leaves 9". You stick a tailstock with center on the far end, but the unsupported middle of that bar is still more than 4 diameters from either the chuck or the tailstock center. So it needs a steady rest or perhaps a follower if you prefer.

I'll bet you can make a case for less than 4x if particular precision is required or if you're having chatter problems. I guess I had better get started on my ball bearing rest because I don't use my steady near as often as I should.

Interestingly, I went looking for an "official" recommendation in my 4 good turning textbooks and got absolutely nada. Everyone vaguely said to use a steady when turning "long skinny work such as shafts". I was suprised this august collection didn't yield anything better:

- South Bend's How to Run a Lathe

- Albrecht's Machine Shop Practice

- Horner's Practical Metal Turning (one of my faves and available from Lindsay)

- Smith's Advanced Machine Work (another fave, mines a 1938 edition I think)

I'm sure its due to the many vagaries of workpiece stiffness: material, is it hollow, yada, yada. All combines to make hard and fast rules of thumb dodgy.



02-17-2008, 01:11 PM
About 75% of the time a steady rest is used to hold the end of a long shaft centered while you are center drilling it, drilling and taping it or boring it out.

On a shaft 7-8" long a steady rest would be in the way. From what I understand your turning each end of the shaft down to 3/4" diameter. If the two ends have to be concentric with each other then chuck each end flush with the jaws and center drill them. Then turn the shaft between centers using a lathe dog. You turn one end and flip it over and turn the other end and they should be concentric with each other. You don't need a steady rest for this job.

If the 1" dia shaft won't fit in the spindle then you can chuck it up half way and dial indicate the very end in and then center drill it.

If the shaft won't fit through the spindle and is to long sticking out of the chuck then you will need the steady rest. It's just common sense, it's not magic. The common sense aspects of machine work are very seldom covered in books on how to because your supposed to use common sense. If it looks dangerous don't do it. Think and find a safe way.

It's not a good idea to chuck a shaft and have a stedy rest at the far end and machine it in the middle but it can be done. It's better to steady rest it, center drill it, remove the steady rest and machine it between chuck and live center.

El Cazador
02-17-2008, 04:26 PM
This is why I love the Net. Thanks for the help. As you can see, I need it!
Redlands, CA