I have a hard time convincing people that the best method of checking the true of a level is to check it to itself. There are a lot of out of true levels out there , and they cause a lot of problems , especialy for the finish man.
So , how do you check your levels?
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Replies
Set it on a relatively level surface, shim it until it reads level, mark its location and then flip it 180 degrees. It should read level again. If it doesn't, it's off my 1/2 the amount the the bubble was off when it was flipped.
You're right! That is exactly how I've been doing it for years,[except that I place one end on a nail,mark level, or plumb, and then flip it].
Even when I demonstrate this infalible method, I get skeptics, so my question was actualy about alternative methods.
I've found the easiest way to shim the level is to screw a panhead screw into a 2x, adjust up or down with a hand screwdriver.
mike
Flip it.
I'm sorry, I thought you wanted it done the right way.
Jay: If you are really desperate - put an inch or so of water in a container longer than the level. Very carefully hold the level so that the bottom surface just touches the water surface. The water surface will be horizontal & flat, ergo, level. Not really - the surface of the water will be a curve w/ a radius equal to the radius of the Earth, plus the distance the surface is from the ground, but we won't worry about that small deviation from flat here.
Don
I always compensate for the curvature of the earth when I check my level by the "water" method, it is just that more accurate.
How much does the earth curve over the length of a level? Seems like it would be measured in microns.
19-5/32s of an inch.
Pete for POPE!! <!----><!---->
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"Almost certain death, small chance of success.... What are we waiting for???"
I actually do not compensate for the curvature of the earth when checking a level, who can? You mentioned the curvature and its relationship to the 'water' method of checking a level. I thought it was an interesting comment made tongue in cheek. I made mine in the same vein.I am actually surprised how much abuse levels take on the job and how they seem to retain their level.Murphy's Law says that, "if the level drops it will fall from the heights point of the roof, find a clear path through all framing and floor levels, bounce off the concrete basement slab, land and knock over the meanest tempered plumber's fresh cup of morning coffee."
Sorry for my reply--I din't know you were joking. I have trouble here a lot with that. I guess I'm hyper sensitive! Another way would just be to float your level in a pool of mercury. ;-)
Concerning levels (or for that matter, power tools) falling and finding the clearest path to the lowest and hardest surface--It's sort of the way a power cord will wrap itself around something that a cowboy couldn't get a lasso around.
Edited 4/9/2005 8:39 pm ET by Danno
Danno: Nah - we can't use mercury - it's a nasty environmental contaminant. Will cause brain damage in your level & it will never work right.Speaking of splayed walls - My framing carp left his 6 ft aluminum level behind when he left GA for AZ. I could never find out where he was, so I used the level to build my well house. Somehow, I managed to always use the same side as a base & the same plumb bubble for erecting the walls. Couldn't figure out why they were over an inch out at 8 ft above the slab. Then I checked the bubbles. Wow. My house has plumb walls, so Carp must have known and avoided the bad bubble.DonThe GlassMasterworks - If it scratches, I etch it!
<Nah - we can't use mercury - it's a nasty environmental contaminant. Will cause brain damage in your level & it will never work right.>
So that's where they got the expression "half a bubble off plumb"-- from levels that were exposed to mercury.
I bought a post level--'L'-shaped. The level on one of the legs was off and I ended up plumbing the posts by comparing them to edges of nearby houses--hoping those where close!
4.60446E-06 inches in a 48" level.Just off the top of my head.
Jon Blakemore
Yeah, that's about what I figured, plus or minus 7.76 to the minus 8 power. <G>
Somewhere I've heard that the curvature of the earth is 1/16" in 492'. Is this accurate?
"4.60446E-06 inches in a 48" level" Could you translate that into the real world please?
Also, you have to watch out for mountains since they are lighter than valleys.
~Peter
Assuming a radius of 3,963 miles, a run of 466' 10-1/2" would give you a drop of 1/16", measured perpendicular to the tangent line.
Jon Blakemore
Do you also compensate when checking plumb?
Or do all your walls splay out ?
Did you know that door manufacturers make thier door slabs wider at the top so Each edge will be plumb when it is hung properly?
Pete for POPE!! <!----><!---->
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"Almost certain death, small chance of success.... What are we waiting for???"
I thought I was the only one who knew that.
On a releted subject, always use extreme caution when two lasers are being used in the same room. An old timer once told me that two beams coliding could knock the Earth off its axis.
I believe it.
That used to be good advice (how old could your old timer have been if we're talking lasers?), but ever since Ghostbusters it's been determined that you get better results if you cross the streams!
See you on the other side Ruffmike.
Griff
True, he wasn't that old, just an old soul. We have been using lasers over twenty years now, though,
I ain't afraid of no ghost, Mike
Cool movie. Great song came out of it. Long list of fine, funny actors in the company. The sequels never came close - seems they never do.
Are you the keymaster?
Griff
Keymaster? It has been a long time since I saw the movie.
The song is great though, love to listen to it with the kids around halloween.
I used to have a great Jamaican version of it (and there was more than one) that was sung to the rythmn of "I'm a girl watcher"
I'm a ghostbuster, I'm a ghostbuster.....
I love how they'll cover anything in a reggae style. I'll have search for that tape someday, its around somewhere.
C'mon, youse guys - this thread is about checking a level! Any more & I'll call the sky marshalls!This was a serious thread - till I introduced the bit about earth curvature.DonThe GlassMasterworks - If it scratches, I etch it!
Okay, I am not sure what is meant by flipping the level.
I was always taught that you turn the level end for end, using the same edge, this makes sense to me.
If one was to flip a level without going end for end, would that level be acurate if the bubble read the same?
That is my question, and I'm stickin' to it.
Well, Mike, which Hemisphere are we taking about here?
Griff
I am planning on building a Keymaster station in the Antarctic, and it has to be extremely level, any suggestions?
Will my level freeze?
Not if you have the NEW liquid Nitrogen bubble vials.
Pete for POPE!! <!----><!---->
<!---->
"Almost certain death, small chance of success.... What are we waiting for???"
Well, to be sure, I checked out, I mean I check with, Dana Barrett and we're pretty sure that it depends on two more factors: whether you're planning to build in the summer or in winter (i.e., in daylight or at night), and whether you're going to be between the meridian and 180 degrees or between 180 degrees and the meridian.
Either way though, if you come across a stream of ectoplasmic slime running under the ice, who ya gonna call?
Griff
The only way to do it 'right'.
"What do you mean it's 'last call'? I just got here."
The only problem with this method is that as soon as the water touches the bottom of the level, the surface tension will draw the water to the level and make it look like it's touching all the way along it(unless it's way off). A water level could be used to use as a reference, but the observer needs to be looking from exactly the correct place for this to be accurate. It may be best to use a straightedge to make sure the body is actually straight, then check the indicator. Once the body is known to be straight, THEN check it and rotate it. Flipping it end-over-end isn't what you need to find. If there's too much doubt, probably best to buy a new one since the old one will never be trusted.
"I cut this piece four times and it's still too short."
>>>>"Not really - the surface of the water will be a curve w/ a radius equal to the radius of the Earth, plus the distance the surface is from the ground, but we won't worry about that small deviation from flat here."Don't forget the meniscus!
Jon Blakemore
Your system is fine, but it fails to take into account the gravitational attraction of moon and sun, especially when they are in spring tide configuration. Also, you should check for gravitational anomalies -- the USGS publishes good maps on this.
> Also, you should check for gravitational anomaliesEspecially around Gatlinburg TN.
Flipping the tool is also the way you check your framing square. Set the fence of the square on a piece of plywood and mark the line with a fine pencil line. Now flip the square and place the fence along the same side of the plywood and compair the pencil line to the flip side of the square. If they're the same, it's square. If not then it's out of square one half the distance of the difference. To adjust, use a pointed steel punch and dimple the square on the inside corner if it's less than 90 degrees, or dimple on the outside corner if it's more than 90. Keep checking for squareness and make as many dimples as it takes.
That won't work because plywood is now made to conform to the curvature of the earth.
It has no straight sides!
Pete for POPE!! <!----><!---->
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"Almost certain death, small chance of success.... What are we waiting for???"
The Earth is flat my friend, that's why plywood's flat. You ever been to Indiana? Go ahead and square yourself up. Flat.
You ever seen western Minnesota -- east of Fargo? I was driving a Norwegian relative through that area (an ancient lake bed) and he looked out and said "You can see the curvature of the earth!" I checked, and he was right -- the view curved off in all directions, just like on the ocean.
Awwww come on the earth is FLAT111
In the store, when buying a level, I'll compare two to each other. If they match, I flip one and compare them again. If they mismatch I try another pair, if they flunk too I look elsewhere.
Yeah, when buying a new level in a store you can't always check it properly. I've tried different way to do it without driving a nail into thier wall or marking up thier paint job with a pencil. The method you descibe is as good as any for a quick look see.
Years ago I started buying only levels that could be adjusted. That way , after my guys were done tossing them around a truck bed , or dropping them off of staging, I could bring them back into true.
Do not assume they are any good off the shelf.
Once you have a 'known good' level, you can use it to check others you may have.
Sounds obvious, but I once watched a guy shopping for level messing around with shims, and testing all different ones.
"....they cause a lot of problems , especialy for the finish man."
It has been mentioned in earlier threads never to put a Johnson next to a Johnson. Howserever, most problems occur at the footings and become progressively worse with each correction. In order to assure accuracy, the finish guy should show up for work about 4 months early and check the Stabila of the Formworker's Johnson.
When I was a superintentent on large jobs , I generally ckecked every level on that job and quarantined the bad ones. That approach always got me in hot water with the idiots that could not fathom the infallability of the 180 degree turn method.
Most of the errors in plumb and level occur as a matter of ignorance and laziness.
You should see our house. The contractor/builder's level was off by at least 1/8" in 4 feet, and the entire house is off that way, floors and walls. Windows crooked, etc.He apparently had a policy, though, of not changing the orientation of the level too often, so the entire house kind of tilts towards the back.
I remember plumbing steel stud door jambs by eye-balling them against another high rise. Accurate and fast.
Everyone has a level with at least one or two bad vials. One of my favorites is a 6 footer, it has 5 vials, 3 of them suck. Of the two remaining, one is bang level and the other is bang plumb but only on one side because the beam has a slight bow. I can use that level with great accuracy because I am familiar with its flaws. I would welcome anyone to check my work, but keep your hands off my level.
The above replies (particularly the one using a screw into a flat, stable wood surface) is fine for horizontal level checking...but how about vertical plumb? Here's the way I do it:
put a #16 finish nail firmly in a wall down near the floor, slide the botton of the level up against it and move the top of the level back and forth until the bubble says plumb, and mark with a pencil. Then flip the level around (side-to-side, not bottom to top) and without looking at the original mark, remark on the wall the second plumb point. If they are different, the midpoint of these two marks will be the plumb point. I mark that point, drive in a nail at that point, put the level against it, loosen the secrews holding the bubble mechanism and adjust until it's plumb.
Repeat for the bubble at the bottom.
That is exactly the way I do it! Can you believe that there are those who cannot see the sense in that?
Jay
Been doin it that way for years.
Sounds like a great submission to FHB to include in their 'tips n techniques'
BruceM