I just bought a new 60 cm bubble level from a relatively reputable brand - Empire - and I had to go through six of them in the store before I found one that was accurate. I own three longer ones, two of which have been miscalibrated since the day I got them. The third one would have been as well, but luckily I checked it before buying.
It would be so easy to just add a small adjustment screw for calibration. I don’t understand why they don’t do that. Even the more expensive ones I’ve seen don’t have one. I’ve developed serious trust issues because of this.
Also, in case you didn’t know, you can check the accuracy by rotating the level 180 degrees and seeing whether the bubble stays in the same place.
If you have a miscalibrated bubble level on a truly level surface, the bubble will sit more toward one side - say, left. Flip it 180 degrees, and it’ll shift to the right.
On an inclined surface, the level might read level one way and show incline the other way.
Here you could just adjust the screw until the bubble stays in the exact same spot no matter which way you flip the level.
That assumes that it’s the bubble tube that’s not installed evenly but doesn’t remove the problem the other person suggested, which is a non-flat or non-squared other side?
Not entirely. Like the OP mentioned, (may not have explained it well enough) you would just adjust the ampule’s rotation so that it will report the same offset either direction the level is oriented. I.E. if the bubble is 5mm to one side of the ampule when the level is facing one direction, it should report the same offset but at the opposite end of the ampule when the level is reversed.
I see what you’re saying. Make the bubble offset “evenly”, but then you’re doing Kentucky windage with your bubble everytime?
I think this becomes entirely moot if you mark which side of your level is the “accurate” side. I have a torpedo level that’s damaged on one side, but I like that it has magnets, so I explicitly use the magnet side which I know is accurate.
does that make a practical difference?
Not at all, but neither does OPs request hahahah. There are more hard core leveling devices if a cheap bubble level isn’t good enough.
Okay, now I’m picking up what you’re putting down. Thank you! Off I go to test my levels! 😅
Here’s one extreme example of what they are describing, other situations might also be bowed, twisted etc.
Doesn’t matter. Most levels aren’t “two sided” like that anyway but have a top and bottom.