On the subject of spirit levels...
I bought a 2 metre Stanley spirit level recently, if I put it on something showing level when it's one way round, it's about 5mm out when turned around. I suspect then that the error is half this at about 2-3mm which across 2 meters is next to nothing.
But would this bug you?
That is not really very good ... Most decent levels are 0.5mm per M ... so if yours is 3mm across 2M it is a fair bit out.
I also have a level with 0.1mm per M ... but these are not general building levels.
It depends what I was using it on.
Yes. I'd take it back.
Tim
Extremely but name brands are usually adjustable.
Yes, a measuring tool should give consistent results no matter which way round it is used. Have a look to see if it's adjustable, if not take it back (and check its replacement before leaving the shop). You don't need something dead level to check, just something levelish. A good level will show the same direction offset indication either way round.
Not adjustable? Most decent long ones are.
0.02mm / m here but only 200mm long.
Cost new was about 300 quid but I didn't pay :)
What on earth do you use one of those for? If my maths is right, it should be showing "out-of-level" for anything over 4 microns difference between the ends.
If I told you I'd have to kill you :)
Page 30, Stock code 960-603
It says it's adjustable, how much do you spend on a more accurate one to reference it from?
You don't need another one. You put it on something close to level and adjust it so it reads the same when you turn it 180 degrees. Then you can put a shim under the end so it says level and test it again to be sure.
With less than 4 micron difference turning the 180 degrees accurately might be fun but I guess the "something close to level" could have a couple of stops to place the side of the level against. In fact thinking about it you don't really want a solid "flat" surface underneath either. How do you know that surface *is* flat and not slightly up or down, or just have a bit of fluff on?
Looks like an open jig with fours stops, one for each end underneath and one for each end on the side. Then multiple checks with the "level" of the jig being adjusted to check that the level being tested has an equal and opposite "error" for a range of "levels".
It's exactly the same priniple used to DIY your own white noise azimuth test tape for lining up the heads on a domestic 4 track stereo tape deck. With care, you land up with a test tape where the left and right heads are in absolute azimuth alignment.
Hint: the process involves the use of triple play tape which can be played flipped over to playback the white noise test recording from the back of the tape in the reverse direction. A modicum of "Rinse and Repeat" being required before arriving at the final test recording.
I have one similar to the slightly less accurate one (960-602) and even tha t is too sensitive for most applications. Didn't cost me £278, though..
down,
Not convinced. In the case of a bit of fluff it could move or be carried on the underside of the level. With a hump you have to have the hump touching the level in exactly the same place either way round and have the level end touching the same side of the hump not the other. A dip may not be uniform so you have to ensure the end contact points are the same for each orientation of the level.
underneath
FSVO "works fine". I'm not making any assumptions about the symmetry of the vial, assuming the thing uses a vial.
ISTR that this level indicates within 4 microns over its length. A fine human hair is over 10 microns. These really are tiny amounts, if you did go for wiping it would have to be a clean and absolutely lint free cloth.
Designed is not the same as an actual physical object.
I imagine that the proper methods have a lot in common with the procedure for assembling gauge stacks, as described in the catalogue linked earlier,
page E-17.
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