Lathe Leveling - Acceptable test cut delta?

[Jmanb13]

I just went through the process of leveling my 1946 15" Leblond using the process in the two videos below.

This is my first time using a micrometer. To make sure I was using it properly, I measured the same area multiple times to make sure I was getting the same measurement each time and I was getting repeatable measurements each time. After a few tries I was getting repeatable measurements pretty consistently.


The test bar that I cut was a 2.75" solid aluminum bar about 14" long.

What would be considered a "good" enough delta between the 2 measurements?

Obviously if your doing super precision work it would be a little different than hobby garage work.

On the test bar I did the 2 cuts and I got a delta of 0.0010" and the 2nd time I measured I got a delta of 0.0008" .

I'm assuming that is a pretty solid number for 70 year old lathe?

 

[Jmanb13]

Sorry I just realized I put this in the general forum and not the "beginners" forum.

 

[NCjeeper]

I used the same process to level my 13x40 Enco.

 

[mikey]

As far as I know, there is no standard for a 2-collar test. If its good enough for you then its good enough. 0.0008" over 14" is more than good enough for general work. Can it be better? Sure, it can be better but it will take a lot more leveling and fussing. And it will change over time and have to be done again.

One day, you will have a project that requires great precision. You can check and adjust to get things better then but under a thou over 14" will be fine for most stuff we do.

 

[darkzero]

Like Mike said, if it's good enough for you then that's all that matters. It all depends if you're making model airplane parts, full size aircraft parts, or space shuttle parts.

What a coincidence. I was actually checking mine this morning. I haven't check it in quite some time. I noticed some slight taper the other day. I live in earth shake country, while we've haven't had a big one in a long time (knock on wood), we have had some small quakes here & there. I usually check after were have any type of earthquake but I've been lazy.

I got .0006" over 10" today. While that's not terrible I did have it half of that the last time I leveled it, 2-3 tenths before. I'm not in a rush to bring it down but when I get a chance I will.

Yeah I know, I didn't bother making an under cut, I just let it ride along. I didn't feel like wasting that piece of stock. I had a piece of stock that I normally use but I have no idea where it is right now.

 

[Jmanb13]

Thanks guys! I think I'll leave the lathe as is then. No reason to shoot for sub thousands in a hobby shop where i'm just a beginner and not making anything super precision.

 

[Tozguy]

If I got a delta of .0008'' over 10'' I'd be happy. If it was the end away from the chuck that was largest I'd be ecstatic.