VIS 12" level vial graduations

[fillister]

Hello,

I've had 2 of these VIS levels for decades as I purchased them new to setup my 14 - 40 lathe. Now that I'm in my 4th month of retirement I have an unlimited amount of free time to spend in the shop. So I was wondering if some kind person would be able to explain to me what each graduation line represents, I'm guessing .00005 but confirmation from someone much more knowledgeable would be appreciated.

Thanks

Greg T

 

[RJSakowski]

Easy to check out. Place the level on a flat level surface. If the surface isn't level, you can rotate the level to find an orientation that is level. Thn put a shim under one end and not the deflection. If your thinnest shim moves the bubble off scale, you can mount the level on a long bar and repeat the process.

To calibrate a level, place it on a flat level surface and note the reading. The rotate the level and note the new reading. If the position of the bubble moves with the rotation, but reads the same, the surface is level but the level needs to be adjusted. If the position of the bubble doesn't change, then the level is correctly adjusted but the surface isn't level. Usually, it's a combination of both.

It may be easier to start this with a carpenter's level to get the hang of it. Once you have the procedure down, you can move to the precision level. A good practice is to mark a line on your surface so you can place the level in exactly the same orientation as you rotate it. A piece of masking tape works.

 

[metalmagpie]

Those are 10 arc second levels. The way to figure that is 3600*arctan(.0005/10).

I believe that means that you tilt the level 10 arc seconds and the bubble will move one division.

To figure out how much you have to lift or lower one end to move the bubble 1 division, let the unknown equal y.

Y/12 = .0005/10

Y = 12x.00005 = .0006"

My conclusion is that one division equals 6 tenths.

I could easily be wrong, and indeed if so would welcome someone explaining my error.

metalmagpie

 

[WobblyHand]

For these kinds of levels with higher sensitivities, you need to be on a firm floor, like concrete. If you try this out say in an upper story, or a wooden floor, you may find the level shifting as you weight your feet differently, independently of moving the level. When my wife stepped into the kitchen, the bubble moved.

The one I have is a cheap eBay thing, but it is sensitive to where I stand, while making the measurement (in my kitchen). I had to go to the basement concrete so the minute floor deviation was not fooling me. Of course, it's a bit cooler down there so I had to wait for the level to reach thermal equilibrium. If you don't wait, and you have a 0.02mm/m level, well, it's going to lie to you.

Ordinary standard thickness gold leaf is about 0.107um minimum. To get to 6.1um, you would need 57 sheets, which is a lot. I think 6.1um over 1 foot, is equivalent to 0.02mm/m sensitivity if I did the math right. You can get silver leaf, 25 sheets for $10.07, the sheets are about 0.32um, to get 6.1um, you would have to stack 19 sheets, give or take. Silver will tarnish. This leaf stuff is so thin that a slight draft will send it flying everywhere!

 

[benmychree]

Most precision levels, such as the Starrett #`198 are graduated at .0005" per foot per graduation. That is sufficient for machine leveling.

 

[fillister]

Thank you all, so if by accident or purposeful effort I have been able to get the lathe bed twist down to 1 deviation or .00012 when having the level set on the cross slide and travel from the headstock to tailstock I'm doing ok. Now on to running a two collar test....

 

[benmychree]

Thank you all, so if by accident or purposeful effort I have been able to get the lathe bed twist down to 1 deviation or .00012 when having the level set on the cross slide and travel from the headstock to tailstock I'm doing ok. Now on to running a two collar test....

I suspect that your level is nowhere as sensitive as you represent, I wonder that you added one too many decimal points, a level that sensitive would take a very lot of time for the bubble to settle down. Try it's sensitivity with a sheet of cigarette paper and see how much movement you get.
Rolling papers are .001 thick, at least those in my collection.

 

[metalmagpie]

I had difficulty reading the label on the level in the picture. In fact, I originally misread it to say .0001/10 while in fact it says .0005/10 which makes it six tenths per division, roughly equal to the Starrett 199.

 

[benmychree]

I had difficulty reading the label on the level in the picture. In fact, I originally misread it to say .0001/10 while in fact it says .0005/10 which makes it six tenths per division, roughly equal to the Starrett 199.

Yes, and quite close enough for machine leveling.

 

[fillister]

Well it never hurts to check, so following RJ's method I have an import surface plate that I placed on a cast iron machine top and placed the level on the surface plate. I rotated the surface plate until the bubble was centered, I haven't been to the store to purchase rolling papers but I do have .002 shim stock. placing the .002 shim under the very end of the level results in a change of 5 to 6 division marks.