I hope this isn’t too dumb, but is there a trick to properly sighting a vial level? The bubble SEEMS to be in the middle. Do you just eyeball it and hope for the best, or am I missing something. Seems a little bit of error can telegraph into a big one further down the line. How can you be sure the bubble is EXACTLY in the center?
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You've got two lines on that vial and the level is true........right? Bubble dead on in the middle of the two lines........or pretty darn close. For perhaps longer leveling, a transit or builders level or laser.
That's all there is to it.
Remodeling Contractor just outside the Glass City.
Quittin' Time
Edited 3/10/2004 10:17 pm ET by calvin
The practiced eyeball can see a lot! Yup, that's how you do it.
Biggest problem with a spirit level is that most of them don't give an accurate reading whether you can see the bubble or not. I recently bought a cheap Stanley 6'6" jamb level at Lowe's. I spent nearly an hour going over each of the eight levels (of the same type). After lots of comparison and checking each bubble on all eight levels I found one of the eight that was close enough that I bought it. As I left with the level another guy walked out with a pre-packaged deal on two cheap levels that were obviously uncheckable because they were wrapped in cardboard and shrink wrap.
If you want a good 4' level, get a Stabila for about $70-80. Only thing I know of that's guaranteed to be accurate. Last time I checked there was a deal on Stabilas from tool crib: 4'er and 16"er together for $70.
Something is what it does.
Either Stabilla or Levolution. Anything else is just
something else.
brand X
I see the same thing. One or two out of every ten levels is OK. Gotta be tested in store.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I like them line levels that have soapy water in them..on a windy day I got a WHOLE BUNCH of bubbles..<G>
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Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations.
Johnson levels are very popular around here; and have a good reputation for both accuracy and longevity..
Phill Giles
The Unionville Woodwright
Unionville, Ontario
Yep, when buying a level, always check it. (Easiest way is against another level -- check it one way, then reverse one level and check again. If they don't agree one way or the other then one of them is wrong.)
Generally, with a well-made level, the bubble will be almost exactly as wide as the space between the two index lines on the glass tube. Get the ends of bubble to line up with the two lines (or get each end to be an equal distance from the line on that side) and it's level.
For longer runs, a water level is far more accurate than a spirit level. The water level is essentially a clear hose with water in it. Once you get all the bubbles out (important!!) then the water level at the two ends will always be equal. It's a little tedious to use (you need two people), but one can be used to replace fancy transits or laser levels, and it can "see" around corners, something you can't do any other way.
Those bubble sizes change a bit in extreme temperatures no matter the brand!Something is what it does.
To avoid 'paralax' (sp) I make sure I am looking squarely at the vial. That is to say, I sight 'through' the vial and try and make sure the 'back half' of the vial lines on both sides of the vial 'line-up' the same. It's a lot harder to explain in words, but it makes sure I'm not looking at an angle.
Let's not confuse the issue with facts!
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Quality repairs for your home.
Aaron the Handyman
Vancouver, Canada
play with the level a bit. what I do is get something (2x4)
that is straight and longer than the level and work on a surface
as long as the 2x4. with the level on the 2x4 (marked so that
the level can be reliably put in the same place) shim one end so that
the bubble is in the center as well as you can tell (I use a feeler
guage to shim it up). next increase the shim (0.001 at a time)
until you move the bubble enough that you are absolutely sure
it is not centered (but no more). the change in height is an
upper limit on the the possible error in reading the level. the
% error is that change divided by the length of the 2x4.
suppose e is the change in height in inches and the length of
the 2x4 is 96 inches. then the slope is e/96 and that decimal
is the best estimate of the error in inches per inch.
then take that ratio and multiply it by 57.296 and you have
the error in degrees.
Is this for a level or the Hubbel (sp?) telescope? :-)
That means for an error error of 1/8" at 8' The accuracy is 0.0746041667 Degrees.
1/8" error in 8' is %0.13 slope. [1 / (8*96)]
I know from experience that I can with a good 4' level, or a cheap one I have calibrated, I can layout and follow back a 12' line vertical or horizontal and be within 1/8". That's %0.08 slope!
IIRC, the site tubes of a good level are parts of an arc with a radius of 40". If the bubble at the end of that radius moves 1/8", (which would put it outside the lines,) then the bubble has moved 0.1790 Degrees (if you trust my math, I've got a bridge I want to unload cheap.)
OK, an 1/8" on a 12' R would be 0.0497 Degrees. "Am I doing this right?" He wails.
Anyway. . . What's the smallest movement that you can notice on a bubble?
SamT
A little off topic, but what are everyone's opinions of the "Smart levels"...the digital modules? They take about two minutes to calibrate, and read to 1/10th of a degree. They also do slope, etc. One advantage is not having to be in a position to sight the bubble, just read the display.
Lots of racers use the modules for doing front end alignments, esp camber.
Thoughts?Jake Gulick
[email protected]
CarriageHouse Design
Black Rock, CT
When I was building pipeorgans..I used a smart level for the main facade pipes..so much lead in them that they had to be just about deadplumb or they would collapse from thier own weight and gravity..after I set the largest that was in front of a Rose window in a church..(St. Lukes, Mobile Al. ) it looked crooked compared to the verticle muntin..turns out the WINDOW was off..12' Dia....it had to be R&R'ed much to the dismay of the installers..they actually got pizzed that our work was so accurate!!!
I like them..mine was in my shop fire and I have yet to replace it tho'..with my log castle a smart level is overkill..a rock and a string is as good as it gets, which is pretty good combined with a framing square..
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Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations.
My grandfather built his own house sometime around WWII. He had a brother-in-law who was a carpenter and lived right across the road from the new house. One evening while the framing was going up, the BIL wandered over and in the course of conversation asked Grandpa how he knew it was plumb and level. Grandpa said, well, he looked at it. BIL got mad, stomped off to his house and came back with his level. Checked all the framing, got madder and madder, and stomped off again without saying a word, because it was all straight and level.
Of course it was Grandpa telling the story, years after the BIL died, but it's a good story even if it may not be 100% literally accurate.
I got the 24" one from Tool Crib. Love it, great for checking roof pitch, figuring a plumb cut, setting drain fall,etc. I would say less that two minutes to calibrate. It is surprising how much a 1/10 of a degree is though. More that you would expect. You did not mention the hold function or audible level indication. Those are really handy in tight or dark spaces. It reads in degrees, %, ft/inch and you can use it for conversions, prop it up to desired angle, push the mode button and see what the other two units are. Like many tools the imagination is the limiting factor.
Well, truth be told I was a little nervous I would get abused to no end for even bringing it up! I have one, and love it. As you mentioned, it has lot's of uses. I wish I had a longer frame for it.
I've spent time in the car prototyping industry, working on flat tables (calibrated over 20 feet in the thousands) etc, so I'm used to dealing with digital measuring devices. We would never use a bubble, as it introduces judgement. Engineers hate judgement! But carpenters, good ones at least, have pride in their judgement.
I think I am careful, but I look for ways to increase my repeatability, and reduce the chance that I can miss something. I like the fact that when it says 90.0, I know it's pretty darn close.
The only question I have is: Is a good bubble level more accurate? If so, by how much, and the better question, how much of the time? I love the Smartlevel, but I just want to be sure I don't love it out of ignorance!
Jake Gulick
[email protected]
CarriageHouse Design
Black Rock, CT
Stabila's are accurate to .027° (according to the web site). Over 73", this is a max error of .034", a little more than a 32nd.
I don't know how accurate a smart level (I couldn't find anything with Google) is calibrated to, but over the same 73", if your reading is 90.0°, you could be off by exactly 1/16th.
Of course, this is assuming that you are reading the Stabila perfectly.
Jon Blakemore
Interesting! So, a Stabila has the potential of being three times more accurate! Hmmm...but still the question is, as you say, the accurate reading of it.
Frankly I didn't expect them to be able to claim such accuracy. Interesting....Jake Gulick
[email protected]
CarriageHouse Design
Black Rock, CT
Hasbeen mentions the "practiced eye." I think we can agree that our eyes are good at accurately centering things. We notice the slightest crookedness in a hung picture. The peep sight works so well on rifles because the eye naturally centers the target in the peep. The same for centering the bubble in the vial.
I once saw this dufus working at a building supply who would go up to customers in the spirit level area, grab a four foot Stabila, and throw it on the floor. His intent was to demonstrate that it was a sturdy level and that Stabila would replace it for life if it ever failed to be accurate. Of course, nobody would go near the one he'd just thrown on the floor, nor would they consider the others on the shelves, for fear that he'd used them in earlier demonstrations.
I close one eye while sighting the bubble. Keeps my eyes from arguing with each other. I hate when they do that.
Kevin Halliburton
"In him the whole building is joined together ..." Ephes. 2:21
Isn't there a scripture that says, "Let not your left eye know what your right eye is looking at, lest when it wanders, both of them must be plucked out and cast from you"?
;-)
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Yeah, and it's looking at SHRIMP!!!!!..ooops, I just ate my eye.
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Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations.
Yea, Hezekiah 3:14.
There is also that verse that warns us about the danger of looking directly at the beam of a lazer level by comparing it to more obvious eye damage.
Matthew 7:3 (KJH) And why beholdest thou the speck of sawdust that is in thy brother's eye, but considerest not the beam that is in thine own eye?
Kevin Halliburton
"Do you see a man skilled in his work? He will serve before kings; he will not serve before obscure men." - Solomon
For the last 20 yrs. or so I have only used levels that I know can adjust as the need arises. I buy only levels with vials that are screwed into place so that I can loosen them and readajust as I need to. the only way to check a level is to itself. Put the level on the wall and draw a plumb line or a level line. turn the level 180 degrees ( making sure that you are using the same bubble ) and draw another line .If the lines are identical then that vial is reading true, if the lines diverge then that bubble is out of whack by half the distance of the difference between the two lines.
when in doubt use a plumbob, they never lie.
"When in doubt use a plumbob, they never lie."
Or use a Stabila.
Jon Blakemore
Or a water level... I keep checking my level against the water level and eliminating bubbles as they get too far out of whack. I'm down to three bubbles I can count on - One more and it's time for a new "adjustable" model.
What do you guys recomend in the adjustable models? I know Stabilas and Levelution keep getting the nod here but they can't be "tweaked" back in line can they?Kevin Halliburton
"Do you see a man skilled in his work? He will serve before kings; he will not serve before obscure men." - Solomon
If it is a Harbor Freight level, the bubble should be under one of the lines or between the line and the end or somewhere in between.
If it is a Harbor Freight level with laser, then the above applies but to get the laser line level, then the bubble should be elsewise different.
I hope this is confusing, but you deserve to be confused if you use a Harbor Freight level.
A better level would be something like a Wild II transit. Or perhaps a Starett machinists level. But then, the curvature of the earth must be taken into account.
~Peter
FHB used to have a couple of web pages discussing the different styles of levels and included information about the sensitivity of the different vials. But it is apparently gone.
BTW, I like to close both eyes. Removes all doubt about how to read the level.
I just went and looked at my 48" and it's says it's an "American" brand, I've been using it for like 20 years+ so I'm in HD and see a display for laminated wood something brand? maybe american or stanley or ? but it almost knocked me over cause I've been struggling to see the bubble. Yep one of the dangers of making it to old age. Any way the thing was it had yellow juice and I could actually see the bubble, wow. So now I know there is hope for old blind dogs. It's not the level after all - it's the eyes that matter.
Clay