Square type spirit level vs. Shaft spirit level

[Friendly non murdering Sword]

I will probably have to buy a spirit level in the near future to level out my lathe since I can't get the last bit of taper out of the machine. At least in Europe there are two common types of precision levels and that would be the square type spirit level:



And the Shaft type spirit level:


And I was wondering, for which use cases do I need the square type and when is a shaft type better suited? I can imagine for lathe leveling both should be equally fine, but I also want to buy the more versatile one for any future leveling tasks that might occure in a hobby machine shop...

Who has worked with both and can enlighten me?

 

[NC Rick]

I would much prefer a longer level, one which can span across your ways. Also one of pretty good sensitivity.
I recommend something like this:

98-8 Machinists Level with Ground and Graduated Vial

The Starrett 98 Machinists Level with Ground and Graduated Vial includes a cross test vial. 200mm (8") size, without case.

www.starrett.com

I have 2 10” which is really nice but unnecessary.

 

[Richard King 2]

It depends on the applications you have in the shop. Most hobbyists only need the bottom level. The square is used when you have to align angle blocks or vertical ways. What brand lathe are you aligning with the level? Is it used or new? Worn machines normally cut a taper bigger on the chuck end of the shaft your turning. The ways are worn more there and the saddle moves toward the operator. If it is a new Asian made lathe, you can level align the bed perfect and it cuts a taper because you have "Push away" or tool pressure bends the shaft or the head-stock is not aligned or parallel to the ways. After you align the bed at the chuck end and Tailstock end, set the level on the cross-slide or the top of the compound and move it up and down the bed. not removing the level. That will show wear in the bed.

 

[RJSakowski]

The square level will do double duty as both a precision level and a precision square. In addition to checking for plumb, the square is useful for calibrating a squareness gage for subsequent checking of machined part for squareness.

 

[benmychree]

The #98 is not sensitive enough for final lathe leveling, it measures only .005" per graduation, rather than it's big brother, the #99 that is graduated .0005 per graduation.

 

[akjeff]

Sometimes you just gotta "run what ya brung". All I had when I leveled my lathe was a good old Starrett 98, and it cuts an 8" unsupported test bar to within three tenths.

 

[eugene13]

A Starrett 98 is close enough for me, I work on cars, not the space shuttle.

 

[JRaut]

I’d venture to guess most of us on here have never so much as shown our lathes a carpenter’s level.

I’ve got a few fancy levels in my quiver, but my old Logan 200 cuts straight enough as is, so I never bothered leveling it at all.

That said, a box level sure is a nice bit of kit to have kicking around. Like @RJSakowski says, it can run double duty for you.

 

[Richard King 2]

If you eyeball a line on a bubble on a Starrett 98, 005" per line, you are with-in .0005 to 001". The new level that costs around $150.00. To me that is close enough on the bed of a lathe. Then you can tweak it taking test cuts. I own 2 Starrett 198/199 levels that are .0005/12" that cost new over $1000.00 each I work in tenths and millionths when I scrape where I use the higher accuracy levels. Many times I use a less accurate level first to get it close, then use the high precision levels. It depends on your needs and how much money you have. I also own a 4" x 4" square level like the one you show and seldom use it.