Realistic Headstock Alignment Numbers?

[wnchstrtnfldvlle]

So I've been spending the afternoon trying to get the headstock aligned as precisely as possible. The ways have already been leveled using the machinists level. Copying the blondihacks video I turned this test bar, then removed the live center. Taking between .0005 and .001 per pass then adjusting the alignment bolts, I have gotten them to within 4 ten thousandths over 6.25 inches. Slightly narrower at the tailstock end.
For those with the experience and know how, is that going to be accurate enough for regular machining, and all or most rifle chambering jobs? Or should I chase those last few tenths? Any input would be much appreciated.

 

[Huub Buis]

I turned this test bar, then removed the live center

Once you put your live center to the test bar, you will "bend" the bar due to misalignment of the tail stock. Take a shallow cut to make the start and end of the bar of equal thickness or just take a shallow cut, measure the difference in thickness and use some math (addition) to compensate.

I have gotten them to within 4 ten thousandths over 6.25 inches. Slightly narrower at the tail stock end.

4 tens over 6.25 inches is pretty accurate (better than my lathes). I expect that other errors (tail stock alignment, temperature rise in the shop, etc) will have more influence than the misalignment of the head stock.

Check the alignment regularly every month during a year and you know if it would make sense to get it better.

 

[wnchstrtnfldvlle]

I removed the live center, then took the shallow cuts with it just mounted in the chuck. Checking with the micrometer after each cut. I should’ve clarified that.
I just used the tailstock to create the test bar first. That’s when I took the photo.
Thanks for the reply!

 

[Firstram]

I would think you’d want the tailstock end to be the larger size due to tool pressure.

 

[projectnut]

I don’t know the diameter of the bar you’ll turning, but the maximum length it should stick out past the chuck jaws is 4 times it’s diameter. Any further and you’re sure to get some deflection.

The inspection sheet that came with my Sheldon MW-56P gave spec of .0003” new from the factory

 

[Ulma Doctor]

You’d be better off using the lathe and adjust it if you are doing long work and you can’t find a workaround.
Most folks seem work closer to the chuck, so the error shouldn’t matter unless you’re making long shafts.

 

[Huub Buis]

I checked the data of my BF290 head stock (not adjustable). In 2020 I measured the misalignment 0.008 mm / 100 mm or 0.0005" / 6".

 

[ddickey]

Tailstock end should never be smaller than the headstock end.

 

[wnchstrtnfldvlle]

I would think you’d want the tailstock end to be the larger size due to tool pressure.

This is good to know. I could always continue to adjust until the tailstock end is the slightly larger end.

I don’t know the diameter of the bar you’ll turning, but the maximum length it should stick out past the chuck jaws is 4 times it’s diameter. Any further and you’re sure to get some deflection.

The inspection sheet that came with my Sheldon MW-56P gave spec of .0003” new from the factory

The diameter of the bar once cleaned up was approximately 1.5". So right at the x4 length. Also the reason why I was taking very shallow cuts.

You’d be better off using the lathe and adjust it if you are doing long work and you can’t find a workaround.
Most folks seem work closer to the chuck, so the error shouldn’t matter unless you’re making long shafts.

I understand what you're saying. This was just meant to be an initial alignment of the lathe after the initial break in and getting used to the controls and using it phase. This weekend will be a good tailstock alignment.

I appreciate all the replies.

 

[Mikesfab]

I had issues with turning parallel for a while due to wear on the chuck jaws. I was going to move the lathe on but bought a new 3 jaw chuck instead. After setting it up it's within 2/10ths with stock in the chuck, and turns within 3/10ths over 125mm. That's more accurate that the original chuck when new. Machine is a Herless 6230. (Hobby Lathe made for the USA market some 25/30 years ago.)