holding workpiece against spindle center

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TRX
Posts: 109
Joined: Wed Aug 20, 2008 7:30 pm
Location: Central Arkansas

holding workpiece against spindle center

Post by TRX » Mon Jul 24, 2017 9:01 am

Let's say I have a long workpiece that has to be supported on a steady rest since I'll be working on the tailstock end. If I want to use a center and drive dog at the headstock end instead of a chuck... how do I keep the workpiece pulled up against the center?

My old "How to Run a Lathe" book suggests soaking strips of leather in water, tying the dog to the faceplate, and waiting for the leather to dry and shrink.

Besides losing ground in The Eternal Battle Against Rust, threading strips through the holes in the faceplate and around the workpiece and tying them in some way that doesn't try to pull the workpiece to the side as they dry looks like a hassle. And the only "leather strips" I've ever encountered are leather boot laces, and those didn't shrink when they got wet. Maybe they're treated somehow.

Try boot laces anyway? Find "leather strips" on eBay? Is there a better way?

whateg0
Posts: 394
Joined: Sat Mar 28, 2009 3:54 pm
Location: Wichita, KS

Re: holding workpiece against spindle center

Post by whateg0 » Mon Jul 24, 2017 11:35 am

make up a set of parallel bars like a real basic tap wrench, but with holes in the ends to run bolts through to the faceplate.

TRX
Posts: 109
Joined: Wed Aug 20, 2008 7:30 pm
Location: Central Arkansas

Re: holding workpiece against spindle center

Post by TRX » Mon Jul 24, 2017 12:08 pm

I thought of something like that using springs, but I was wondering if there was a better way.

whateg0
Posts: 394
Joined: Sat Mar 28, 2009 3:54 pm
Location: Wichita, KS

Re: holding workpiece against spindle center

Post by whateg0 » Mon Jul 24, 2017 1:26 pm

I wouldn't tighten them down until the steady is running true. In fact, if you used a couple of them at 90 degrees to each other, you could use that to get the work running true and then just bring the steady into the work. YMMV

Harold_V
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Location: Onalaska, WA USA

Re: holding workpiece against spindle center

Post by Harold_V » Mon Jul 24, 2017 3:34 pm

I'm curious why you don't simply hold the material in a chuck, or even a collet. No amount of lashing will create a robust setup, so even if you had success (to some degree) you'd still be limited. That wouldn't be true of a collet or chuck setup.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

earlgo
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Location: NE Ohio

Re: holding workpiece against spindle center

Post by earlgo » Mon Jul 24, 2017 4:02 pm

At the CST in the '70's this is the way we held rifle barrels against the center for chambering.
Unscrew the faceplate a couple of turns.
Clamp a lathe dog on the part to be turned.
Lace a length of nylon rope around and through, etc. making sure the knots are tight and the ends are not floppy and that the dog and part is pulled securely back against the headstock center.
Tighten the faceplate so that it really tightens up the rope lacing.
between center and steady rest.JPG
Adjust the steady rest so the center of the bar is aimed at the tailstock center. This is not an easy thing to do with any accuracy.
centering up the stub.jpg
This will get it done so that the chamber or whatever is in the center of the bar. (If the OD is not concentric with the bore, then there are other problems that need to be fixed.)
Hope this inspires you for your own solution.
--earlgo

TRX
Posts: 109
Joined: Wed Aug 20, 2008 7:30 pm
Location: Central Arkansas

Post by TRX » Mon Jul 24, 2017 5:36 pm

Harold_V wrote:I'm curious why you don't simply hold the material in a chuck, or even a collet.
I had a tapered or non-round part in mind.
earlgo wrote:Unscrew the faceplate a couple of turns.
That sounds like the trick!

Harold_V
Posts: 16434
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re:

Post by Harold_V » Tue Jul 25, 2017 4:00 am

TRX wrote:
Harold_V wrote:I'm curious why you don't simply hold the material in a chuck, or even a collet.
I had a tapered or non-round part in mind.

That helps me understand, but proceed with caution. The slightest misalignment of the part in relationship with true center will cause the part to walk in a steady.

I expect that even tapered or not round objects can be held adequately with a four jaw. That's assuming you aren't relying on a center at the chuck end to determine the proper attitude of the part. If it must be true to the center, then lashing is likely an acceptable solution. Just be careful! :-)

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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