[How do I?] Fix Lathe Runout When Turing Shafts

If you rotate an indicator about a tail stock you will not get an accurate reading. The internals of the indicator are affected by gravity.

A co-axial indicator is not subject to gravity, as the internals don't rotate in the same manner.

He's using a Victor 1740 lathe, he's not anywhere near the limits

When wanting to do precision work with the ts, it's more than likely you will have to adjust for taper everytime you loose and move it, it will hardly ever repeat, depending on how used your lathe is

WoW! Thanks!
I stopped receiving notifications on #4 and decided to check back. I'm glad I did.
I'm very rusty and was never a journeyman but exposed to lots of the caliber of knowledge and abilities I'm finding here.

Good stuff. I was able to make a few passes within .00005 between ends measuring with a Starrett Digital mich.
I was also using a carbide insert. The shaft material is a little on the hard side.

I had swept the live center and it was dead on but moving the tail stock .00025 towards the bit got me much better.

We don't have HSS bits in the shop but that's going to change.
I need to hijack for one tid-bit I have forgotten = What differences in a bearing race fit do you shoot for when you want between a tight slip and a press on?

Here is my playground, there are two drill presses that did not get into the frame. I retired from industrial production maintenance in 2009 to do other things.
I came out of retirement to another company and found this shop un-kept, with rouges slipping in unauthorized and qualified reeking havoc.
After I turned out a few things they needed I was given ownership and permission to lock her down.
What you see is very clean in comparison to then. she is locked down now.
The vice has been replaced with a big Wilton I found wrapped in rags, stuffed into a box and hidden/staged deep in the dark for future extraction.

Thanks

I do believe machinery's handbook has it, but a true press fit I believe is .001 oversized for press fit, BUT I'm not sure that rings true for bearings since that much may cause distortion to the race, I think it also may depend on diameter, in the project of the day I posted a 123 block broke in half that was under a job that ended up being .002 oversize on a 1" diameter, a gear sprocket was being pressed, the guy had to make all new shafts, the ones the customer sent were ALL .002 over and egged, and he had to drill the center of the shafts to remove the sprockets because they would not press all the way on

Thanks, Looking like .0005 may be my ticket.

Thanks Guys,

I have been experimenting and I did get her within .00007 in a 50mm run.
I am using a .0005 Interapid.

Question? If I move the tail stock .001 towards the bit, would it equate a .002 difference in measurement?
So should I move the tail stock 1/2 the amount the run-out is?

I'll say this about this lathe. With the tail stock sitting there locked down and I unlock her the dial does not move. I lock and unlock her a few times and she is solid.

Thanks.

gapi said:

I have been experimenting and I did get her within .00007 in a 50mm run.
I am using a .0005 Interapid.

Question? If I move the tail stock .001 towards the bit, would it equate a .002 difference in measurement?
So should I move the tail stock 1/2 the amount the run-out is?

Click to expand...

OK, you're ready to build parts for NASA

Yes, 1/2 the amount.

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Thanks! Heh! I use a Starrett Digital, sometimes there is too much information yes?

Lol that's funny jim

Try loosening the TS, moving it far away, then put it back and see if it's the same, that's the true test for repeatability. To better answer the 1/2 distance, yes half the distance "because" your cutting BOTH sides of the bar. Even if my tailstock would repeat that good, I'd still check it every single time, symptom of my ocd, I have a bar with collars on each end to align my tailstock, a ground bar can also work, but on my lathe being worn I feel better about the results when cutting forces put in the equation

Thanks, I ran her again today and got her VERY close across 122mm taking .020 roughing cuts. When I made smaller passes of .003 she was almost dead on.

This Victor 1740 has been treating me very well.