Originally Posted by joeycoates
Thanks guys, pretty much what I figured as well. I would like to have a very accurate level, but I do not have machining equipment (although I would like to a some point) so for now I honestly would not have just a whole lot of use for it.
LS Starrett, Brown and Sharpe and Mitutoyo all produce high precision levels in analog (spirit vials with ground graduations) and digital master precision levels.
Typically, the analog levels are accurate to within 0.005" per foot od lineal measurement and the digital master levels will be accurate and repeatable to 0.001 per lineal foot.
The easiest way to ascertain if your level (or any level for that matter) is actually indicating properly is to place the level on a hard surface (like your countertop in the kitchen). It don't have to be square and level, it just needs to be smooth.
Place the level (any level) on the countertop and note the position of the bubble in relationship to the marks indicating the bubble is centered. The swap the ends 180 degrees (1/2 revolution) with the level comong to rest in the same exact spot on the countertop. Note the position of the bubble again in relationship to the marks. Any deviation of the bubble in relationship to the marks is how much the level is 'unlevel'.
You want to have the bubble centered between the indicating marks at the original position (of the level) and rotated 180 degrees. If it's not, the level will never give you a true indication of level or squareness as it relates to vertical plumb..... and the amount of deviation multiplies the error each time a secondary measurement is ascertained (like I stated in a previous post).
I regularly check my precision machinist levels using this method. All machinist levels are adjustable, that is the vial and it's carrier are mounted to the base in a manner that alloows you to adjust the vial to obtain repeatability.
Even a cheap, box store, cemented in vial can be adjusted, it just becomes more complex, either you release the vial from the cement and recement it with paper shims or you machine the base of the level by careful filing.
Always good to check, espceially a cheap box store level because chances are, it's not level in the first place.
You might think that door jamb is square (in relationship to the floor) but is it really? If you never checked the level when the jamb was installed, chances are it's not........
Gravity never lies......
BTW, in essence, thats how you 'tram' the spindle on a vertical milling machine to square the z axis to the x and y axis in relationship to the working surface. Thats neither here nor there however.