So, a Starrett 98 6" level walks into a bar...

[WobblyHand]

You find the level line on a generally non-level surface with your uncalibrated level by rotating it until the bubble is +/- an equal amount from center when flipped. No need to know where that level line is before hand.

Of course, you do have to start with a flat surface that is at least somewhat level, or else your bubble will be out of range in most orientations. But with the 6" 98, this is not very hard (more sensitive levels are harder). It only takes a minute or so to get very close (I've tried it). After that, it's just a matter of how obsessive-compulsive the tool's owner is.

Also, checking the Starrett 98, the slotted screw thread cannot be used for adjustment. It just creates a pivot point. It probably shouldn't be screwed down too tight, either, as while that end of the level rests on a ball-shaped pivot, the bottom of the screw's head is flat. I'm still a little puzzled about this configuration. But on the 98, you apparently do have to use the nuts.

I did level a level that is 10x more sensitive that a 98-6. Finding the level line within the range of the level is a lot harder! If you go in 5 degree increments, you might find it. Using 15 degree increments, you won't find that line, or at least that is my experience. The more level the plane, the easier the level line is to find

At least you have the sense to get a level that isn't too sensitive. Alas, I didn't, and it took me quite a while to get it to converge. My level could tell if someone entered the room, 10 or 12 feet away. If I stood on one side of the level or 90 degrees to the level, the readings were different.

 

[zondar]

My level could tell if someone entered the room, 10 or 12 feet away. If I stood on one side of the level or 90 degrees to the level, the readings were different.

Wow!

Of course, either technique would suffer from the same frustrations caused by hyper-sensitivity. But should I really pat myself on the back for getting such a horribly low-sensitivity level? Lol.

 

[WobblyHand]

Wow!

Of course, either technique would suffer from the same frustrations caused by hyper-sensitivity. But should I really pat myself on the back for getting such a horribly low-sensitivity level? Lol.

In retrospect, yes. You did good. It will be fine. Too sensitive of a level makes you chase phantoms. I can see the effect of the carriage position on the lathe. When better weather arrives, I will make a better lathe stand. Don't want to deal with welding outdoors, a bit too cold for me.

For now, I have to tell myself, I would barely have been able to detect this, (and would have been happy), had I just bought a level like yours.

 

[zondar]

Being a total newbie, my thought process went like this:

1. I need a level for a project that exists only in my mind.
2. I like Starrett products, and their's looks very nice.
3. Um, let's see... I guess a 6" one sounds about right.
4. Hit buy and wait impatiently at the window for the truck to come by.

So I guess I lucked out. Lol.

Go down the rabbit hole far enough, and all of metrology is about chasing shadows. Nothing at all is certain or absolute.