The other day a friend asked me “if something was considered level what’s it level to?” I told him I didn’t know but as long as the bubble were between the lines I was happy. Afterwards, I wondered! What is level? What determines level?
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Replies
Perpendicular tot he gravitational pull of the earth.
Ideally, it would be PARALELL to a tangential line to the earth's surface if it were perfectly round...
Edited 1/28/2007 4:21 pm ET by Reyesuela
isn't it parallel to the tangential line, not perpendicular, at the exact spot where the tangent and the sphere meet?
Yippers. Parallel to the tangential line, which is perpendicular to the earth's radius.
To the eye, a bubble stick will parallel the horizon on a large body of water.
The horizon is curved. If you hold a straight edge up to the horizon you can see the curvature of the earth. Thus it is impossible to parallel the horizon
Pfffth. THat's what I mean. Sorry!
i knew you knew, just a typo.
perpendicular to plumb!
Level is perpendicular to vertical.
Plumb, not vertical. Plumb is aligned with the gravitational pull and level is perpendicular to that. A water level is most accurate since a bubble level with markings can be shifted in the frame of a "level". Also, if a tall building is compared to another one more than a few hundred feet away, they may be plumb at their own location but the sides won't be parallel."I cut this piece four times and it's still too short."
Edited 1/28/2007 1:25 am by highfigh
Also, if a tall building is compared to another one more than a few hundred feet away, they may be plumb at their own location but the sides won't be parallel.
I seem to have that trouble even when the walls are a few feet away lol! Now I have an answer though!
blue"...if you just do what you think is best testing those limits... it's pretty easy to find exactly where the line is...."
From the best of TauntonU.
"I seem to have that trouble even when the walls are a few feet away lol!"I didn't want to mention the problems with that. I have a friend who's an architect and when he was still working in Green Bay, he went to check on a job. finding that one 10' high wall was 8" out of plumb. He called the framer to fix it and they showed up with a chain saw and sledge hammer. Fired them on the spot.
"I cut this piece four times and it's still too short."
"They showed up with a chainsaw and a sledge hammer. Fired them on the spot."
He shouldn't jump to conclusions. Maybe the guy was just going to visit his Mother-in-law.
"Maybe the guy was just going to visit his Mother-in-law."Wouldn't he have had a chainsaw and shovel, instead? Or, a trencher, excavator, etc?
"I cut this piece four times and it's still too short."
plumb/level vertical/horizontal
So you're saying that level is parallel to the horizontal?
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Edited 1/28/2007 8:27 am by DanH
Yes.....is this a trick question?
Well, which is it?
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Well, the last time I checked they called my Stabila's levels... not horizontals..so I'm going to go with that.
not to mess everything up, i read once if they built a really tall building theres a difference between a plumb bob and a level used for plumb, maybe the center of the earth as it goes up, Now i cant remember but it was strange
Tell your friend that building "level" is quality work and "level to what" is a mute point.
Best to you and yours, Chris.
Some say I know too much.
What is level?
well, 'level' is a noun - it's not a person, so it must be a 'place' or 'thing' -
in carpentry, I think I would describe it as 'elements of construction at right angles to plumb' -
it would also be an ideal, to be closely approached, but never achieved -
in science/mathmatics, it has other specific specific meanings -
What determines level?
'plumb' determines 'level'...
....just my take on it....
Level is what everyone here is half a bubble short of.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
I did the math on this for fun. If you take the circumference of the earth as 25000 miles...then divide that into degrees.....you get 69.44 miles per degree. Further reducing this to one minute of degree,,,this is 1.157 miles. Finally one minute of degree on the earths surface is 101.85 feet
So for fun...lets round that off to a building that is 100 feet long. If it has ten foot tall walls...the outside walls if erected exactly vertical will be one minute of angle out of parallel with each other.
So if Blue were framing this....the math shows that the top plates will be slightly wider than the bottom plates. Blue would have to make the top plates 0.0056 inches wider.
This of course of course is negligible...but it still is about 6 thousandths of an inch...something to talk about around at donut time. If you are building only a 50 foot wide structure..then its only 3 thousandths of an inch out of parallel.
The Golden Gate bridge actually had to take this into account...as I dont know what the span is between the towers or their height...but it was a few inches that they had to allow for the towers being out of parallel that far apart.
Stan
Edited 1/28/2007 10:52 am ET by StanFoster
Edited 1/28/2007 10:54 am ET by StanFoster
that also why most lazer are level to 1/8 inch in 100 feet. the lazer light not beneding so at distances it over shooting the curver of the earth.
"that also why most lazer are level to 1/8 inch in 100 feet. the lazer light not beneding so at distances it over shooting the curver of the earth"You're close on that one, actual curvature of earth is 1 inch in 592 feet, making a perfect laser level's inaccuracy about 1/6" at 100 feet.http://www.marineplanner.com/calculators/hordist.cfmBruceT
Done some surveying, have ya?
"I cut this piece four times and it's still too short."
The number is use is 466 feet 10 1/2 inches. I think your figure is way out of line.
Nevertheless, this is still a significant problem.
Another poster mentioned that a plumb robert will be deflected by a nearby mountain. Actually, the mountain is lighter than the valley since otherwise, how would it float about the earth's liquid mantle?
~Peter
Coming soon: "Airplanes of the NFL"
I agree with your figure.I have a spreadsheet that I use (I know, I'm a nerd) to calculate the distance that a level plane is from a perfect sphere with a radius of 3,963 miles.When I input 466.875 (466' 10-1/2") my drop is exactly 1/16".
Jon Blakemore RappahannockINC.com Fredericksburg, VA
Mountains aren't lighter, they're usually caused by tectonic uplift, as in inward pressure on two sides of the plates and one slides under the other, buckling and lifting it until the pressure is sufficiently relieved.
"I cut this piece four times and it's still too short."
I think pm got confused--continental plates are lighter than oceanic plates. But mts aren't lighter than valleys.
Unless of course you are using the lazer over a large heated surface that causes the air to have "Heat Waves" .
Tried a lazer over a 675' x 300' slap set up (set the lazer at the midpoint of the 675'). The sun heated air caused the lazer beam to bend around so much that every time we tried for a reading it would come up different. Ended up shooting grade before the gravel got hot and then again in the evening after it cooled down.
Beam would bounce and bend on the "waves".
Had the same problem with optical transits. And not between the "lines"... but "Exactly Centered" between the lines
with vial levels
Edited 1/28/2007 2:23 pm ET by dovetail97128
"level" is determined by the bubble being between the 2 lines.
Gotta go now..... working on the meaning of life.. i'm close....
Thanks for taking the time to share your knowledge and wisdom on my recent post "What is level?" I've never given that question much thought but, I now look at "level" in a different prospective. Thanks again.
As has been noted (in the posts that aren't simply being silly (now who would post something silly?)), "level" is really most accurately described as perpendicular to plumb. And "plumb" is the angle described by that theoretical infinitely thin, infinitely light, uniform cord suspending a weight in the absence of air movement.But the earth is not uniform in diameter and composition, so a plumb line near a large mountain, eg, will have it's weight pulled ever so slightly toward the mountain. This means that a plumb line doesn't always point through the theoretical center of mass of the earth, and two plumb lines opposite each other on the earth will not necessarily point towards each other along a common line.Thus "plumb", and hence "level", is a localized and somewhat irregular phenomenon, even after you take the curvature of the earth into account.(Not that this means anything for practical construction, but the effects are significant enough to be measured with relatively unsophisticated laboratory setups.)And, of course, if one were to take relativity into account then it would really get weird. My crude understanding is that "plumb" would still be plumb, to the next order of approximation, but "level" would start to get ugly.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Plumb = "square to the world". Level is perpendicular to that. You could also say that level is square to plumb and theoretically, level would be parallel to the world, which we all know is impossible since the world is roughly spherical. Parallel to the world would them make level concentric to the world. "I cut this piece four times and it's still too short."
Edited 1/28/2007 6:09 pm by highfigh
water, protected from the wind and allowed to "settle" will get you as close to level as you need to be. the pyramids are proof that man has been clever for a long time.
you are correct that the effects can be measured with unsophisticated equipment, the slightly above average scribe would have been able to do it over 200 years ago.
as a production framer working in plumb and line crew it wasn't long before i didn't need a string to line walls, like for an apartment or condo type frame with a long straight ext wall. the egyptians used wedges and sighting to survey. anyway now its a curse, i can see when stuff is out of level or plumb just a little and it bothers me. i have to level pictures in public places etc. kinda wish i never learned that skill.
yes when i framed back east i went on the plates as we plumbed the walls useing just my eye, amazing some carpenters dont believe me as they break out srtring lines, i dont know that its bragging just something i was good at, i cut the rafters so it was in my intreast to have it plumb
Plumb really wouldn't be affected on an end gable wall. Both walls would be theoretically out of plumb the same amount and the span would remain the same. The rafters would fit just as well on a plumb pair of walls as on an out of plumb pair of walls.
Perhaps you better get back there and put the level on that stuff.
I'm all for eyeing things and making them look good....I"m just pointing out that the rafters only need things to be paralell, not plumb.
blue"...if you just do what you think is best testing those limits... it's pretty easy to find exactly where the line is...."
From the best of TauntonU.
i think he (bobbys) is referring to lining the walls when he says plumb the walls in his post.
i would always put the level in the corner even if it looked right, and then if you just sight between the two plumb corners (just like you were aiming if your a shooter) and you can "sight" the "line" or "plumb the intersections of walls"
Yes that is what i meant, plumb the corners with a level then sight down the wall with eye while other guys push or pull to straighten the walls, On another note a carpenter friend built a house and he is very good i might add but his window looked out of level just a tiny bit, I walked around and it jumped out at me, He laughed and said he was off a little and did not catch it , i must be the only person in the town that would catch that by walking by.
Hehe. My capenter thinks I'm a freak of nature because I can glance at a piece of lumber lying on the ground and tell whether it's straight. I just hung two pictures 12' apart. One of them is 1/8" lower than the other. It bothers me. :-) The fireplace in my parents' house is nearly an inch too far to the left to be centered on the wall, too. The last house that I've been in that was actually "dead-on" was the one I just bought!
LOL, there IS a thread discussing the pros and cons of obsessive-compulsive disorder in the Tavern.;)Not that I would know anything abouth things like that!
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Whenever there is a piece on Harrison Ford's career, they always bring up that he started as a carpenter and that he has "perfect plumb". They always mention it in reverential terms. It always makes me uneasy for some reason.
Edited 1/30/2007 3:40 am ET by fingersandtoes
That's odd, since his face is so crooked.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
The earth is closest to an ellipsoid.
An ellipsoid. Did you hear that Sphere?
Yep, fatter at the equator, the force of gravity is less there also.
Ozlander
It's an oblate spheroid.
Keep calm, Duane.
Ron
Actually, kinda pear shaped, I believe. A bit of a bulge at the top.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
I know he's not that well balanced - he's a left winger, LOL
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Reyesuela
I work with a guy that picks up a piece of off-fall.........maybe 11-12' long....he can lay it up on the miter saw stand without the use of a tape and consistantly cut it to within 1/2" of center each time, often times much closer.
He hands me one and I'm tickled if I can get it to within 10", and thats rare!
Some people just got it!
Doug
You mean cut it to half the original length? If so he's probably cheating and surreptitiously finding the balance point.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Yea, cut it in half. And I've seen him do it enough times to know that he's not balancing the wood.
In most cases this wood is the end cut of rough sawn wood, not a nice even piece of wood to balance.
Doug
its a curse i'm telling you, you will never be able to get rid of it.
Worked for a lady once that had that same curse and she was the biggest control freak PITA I have ever worked for in my 30 years or so as a carpenter. She would have to have all the slot head screws in the house (including all electrical plates) have the slot running perfectly level, the Venetian blinds had to have the same reveal in every room, she would tell me that the cabinets that I just installed were not level and I would show her with a water level, a stick level, and a laser that they were dead on, but she still insisted they were out, so I would play her game and let her 'determine'what level was.Finally I had it, and when she would go out I would sneak around the house and set some of the screws just slightly on skew, or tip the pictures ever so slightly out of plumb, and 'reset' the blinds. She never said anything, so I don't know if she ever picked up on it.Her only saving grace was that she loved me and had more money than God.
reminds me of the old timer i subbed for one time, had a story about a lady who wanted her laundry room painted the same color blue as her broom handle
painter went and picked up a coupla gallons of blue, when he got done with the room he gave the handle a fresh coat. after it was all dry the lady was comparing the colors and replied that looks excellent! almost an exact match!
"water, protected from the wind and allowed to "settle" will get you as close to level as you need to be. the pyramids are proof that man has been clever for a long time."Come on....we all know the pyramids were build by aliens, not the Egyptians...
Is that on the level?
I don't know, but you might want to square things up with the guys here if it isn't.
I'm just never sure about these things ever since I fell out of the plumb tree and landed on my head.
But at least I know gravity still works!;)
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
That's what they WANT you to believe.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
(bluegrass joke).....how do you know when you got the stage good and level? You get drool coming out both sides of the banjo-players mouth.
Cabinetmaker/college woodworking instructor. Cape Breton, Nova Scotia.
You know why it's a good idea to keep a banjo in your car?
"I cut this piece four times and it's still too short."
No.....why's it a good idea to keep a banjo in your car???Cabinetmaker/college woodworking instructor. Cape Breton, Nova Scotia.
It's good to have something to throw under the wheels for traction.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
And bagpipes don't work as well.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
I like bagpipes. From a bit of a distance- they're pretty loud. I have a friend who does clinics for Fender Instruments/Amps and he was doing a master class at a local music store, talking about the different styles of players, and when he got to one in particular, he said that if you have evil spirits in your house, play the way he does, you can scare them off "and you will be as alone as you want to be", meaning that particular style is definitely not for everyone.
"I cut this piece four times and it's still too short."
The bagpipes are great for holding sand or kitty litter though - keeps the truck clean inside.
It's a good idea to keep a banjo in your car so nobody will put another one in there.Perfect pitch = lobbing a banjo into a dumpster without hitting the sides. Before anyone tells me that they're offended, I like banjo music, especially when it's from people like Bela Fleck and a few others. I also like pedal steel, mandolin and various other odd instruments.
"I cut this piece four times and it's still too short."
You know the definition of a gentleman?
Someone who knows how to play the banjo, but won't.
(I like banjo too....don't tell anyone. I also play mandolin)Cabinetmaker/college woodworking instructor. Cape Breton, Nova Scotia.
What's it mean when a banjo player has three women on his arm ?
He got a new tattoo ! Mike
Trust in God, but row away from the rocks.
I thought the Ancient Egyptians WERE aliens.
"I cut this piece four times and it's still too short."
If you look at the dictionary they show several different means (as related to this subject).Both a plane perpendicular plumb and a tangent to the horizon. In some circumstances they can be sligthly different. But it only matter if you are trying to hit the moon from the earth without any course corections.They also us it to mean flat. And in construction level is very often misused when the question if flatness, such as laying flooring material..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
It gets worse: The center of mass of the earth is not the center of the planet...
What water does when it's resting ...
Bruce
Between the mountains and the desert ...