# So how exactly does a level work?

#### DARQ MX

##### Senior member
So I am re-doing my bathroom with my father and I thought for a sec on how level a level really is. Honesly how can a tiny little bubble be perfectly leveled? What is the scientific explanation behind it?

Since this is the best place to ask I figured what the heck.

#### nsadhal

##### Member
Well, you know that once you've got the bubble in between the two lines, the tube holding the liquid is completely perpendicular to the force of gravity. The only direction the bubble can move is along the axis of the tube. Once that axis is perpendicular to gravity, gravity does no work on the liquid, so the bubble stays in a fixed location. The reason the bubble moves around is because it's lighter than the liquid...

Is there something to your question that I'm missing? As far as "how level" it is... that's simply a matter of precision. They've probably got some precise manufacturing process to make sure that the ruler attached to the little tube is perfectly aligned and such.

#### MrDudeMan

##### Lifer
dang...nothing left to add really.

i thought you were going to be talking about energy levels in atoms so i got really excited to come in this thread. i guess this was ok though

#### CrispyFried

##### Golden Member
the tube the bubble is in is actually curved (convex) so when the tube is level, the bubble will be at the apex (center, or between the lines). if its not level, the center wont be the highest point anymore, and the bubble will be off center.

#### DARQ MX

##### Senior member
yea, lol, nsadnal you pretty much explained it. It hit me when you talked about the horizontal axis and how it is perpendicular to gravity...

#### DrPizza

##### Administrator Elite Member Goat Whisperer
Administrator
Originally posted by: CrispyFried
the tube the bubble is in is actually curved (convex) so when the tube is level, the bubble will be at the apex (center, or between the lines). if its not level, the center wont be the highest point anymore, and the bubble will be off center.
Ahhh, then explain why my level works when it's upside down
I have seen levels built as you've described. That's not the case for most of the levels I've seen on the market today.

#### Howard

##### Lifer
Originally posted by: DrPizza
Originally posted by: CrispyFried
the tube the bubble is in is actually curved (convex) so when the tube is level, the bubble will be at the apex (center, or between the lines). if its not level, the center wont be the highest point anymore, and the bubble will be off center.
Ahhh, then explain why my level works when it's upside down
I have seen levels built as you've described. That's not the case for most of the levels I've seen on the market today.
I'm guessing that the tubes in your level are barrel-shaped, or barrel-shaped with flat sides (the sides facing you)

#### MrDudeMan

##### Lifer
Originally posted by: Howard
Originally posted by: DrPizza
Originally posted by: CrispyFried
the tube the bubble is in is actually curved (convex) so when the tube is level, the bubble will be at the apex (center, or between the lines). if its not level, the center wont be the highest point anymore, and the bubble will be off center.
Ahhh, then explain why my level works when it's upside down
I have seen levels built as you've described. That's not the case for most of the levels I've seen on the market today.
I'm guessing that the tubes in your level are barrel-shaped, or barrel-shaped with flat sides (the sides facing you)
lol yeah i was like "umm they curved both sides?"

#### Howard

##### Lifer
Then again, you could have 2 tubes, one for each orientation.

#### ahurtt

##### Diamond Member
I can't believe this thread is in highly technical. . .If you can't figure out how a level works just by picking it up and examining it, you probably should not be doing home improvements. And you should probably stay away from bodies of water that are deeper than your knees.

#### Geniere

##### Senior member
Originally posted by: DrPizza? Ahhh, then explain why my level works when it's upside down
I have seen levels built as you've described. That's not the case for most of the levels I've seen on the market today?
Many years ago when I was in the instrumentation field, we had a need of tubing with a varying inner diameter. We purchased precision bore glass tubing and reheated it while it passed through a pulling device. By controlling the rate of pull, the tubing diameter, inner and outer, would change. Perhaps a similar process is used to get the very slight distortion needed for a bubble level that would work in any axial orientation.

..

POst X 2-Sorry!

#### DrPizza

##### Administrator Elite Member Goat Whisperer
Administrator
Originally posted by: Geniere
Originally posted by: DrPizza? Ahhh, then explain why my level works when it's upside down
I have seen levels built as you've described. That's not the case for most of the levels I've seen on the market today?
Many years ago when I was in the instrumentation field, we had a need of tubing with a varying inner diameter. We purchased precision bore glass tubing and reheated it while it passed through a pulling device. By controlling the rate of pull, the tubing diameter, inner and outer, would change. Perhaps a similar process is used to get the very slight distortion needed for a bubble level that would work in any axial orientation.

..
I was considering that, but; is it necessary for the level to work?

#### sao123

##### Lifer
my only comment is that the liquid inside the level must have good surface tension...

I have never seen a level where the bubble has been destroyed into many smaller bubbles... even after shaking.

#### DrPizza

##### Administrator Elite Member Goat Whisperer
Administrator
Originally posted by: sao123
my only comment is that the liquid inside the level must have good surface tension...

I have never seen a level where the bubble has been destroyed into many smaller bubbles... even after shaking.
Don't shake the level, drop the level. That'll do it.

I was thinking about the surface tension earlier. Another issue is the adhesion between water/oil/alcohol (or whatever the level is filled with) and the glass cylinder. Given a tube that isn't excessively long, wouldn't the curvature of the surface of the liquid be sufficient, rather than a requirement for the tube to be barrel shaped or bent?

As a 4 foot level should be accurate to within the thickness of a dollar bill, I find it nearly inconceivable that a glass tube could be manufactured with a "barrel" shape to the level of precision necessary, at least for the price of levels today. I just grabbed a small glass tube from the chemistry lab. I had no problem using it as a level.

#### RossGr

##### Diamond Member
If the tube were flat why would there be an equilibrium between the lines? Wouldn't the bubble be as stable at any point in the tube?

#### CairnGorm

##### Junior Member
Good levels can be calibrated, or broken bubble replaced and then calibrated. Take a nail and pound in part way into a wall. Wrap a plumb bob around the nail. You now have a perfectly vertical line...mark the top of the string and bottom...2 points equals a line. Now you can use either a rafting square or draw a 3-4-5 triangle and you now have a horizontal line perpendicular to the vertical line. Rest your level on this line and calibrate accordingly. Use a sharp pencil and take your time.

#### bonkers325

##### Lifer
i think he really wants to know how well calibrated his level is

#### CairnGorm

##### Junior Member
That is also how he can check it.

#### CrispyFried

##### Golden Member
Originally posted by: RossGr
If the tube were flat why would there be an equilibrium between the lines? Wouldn't the bubble be as stable at any point in the tube?

I would think so. as long as the bubble isnt at an end and is stationary its level.. curved tubes can indicate how far off level something is if its calibrated though.

#### 0roo0roo

##### No Lifer
Originally posted by: CrispyFried
the tube the bubble is in is actually curved (convex) so when the tube is level, the bubble will be at the apex (center, or between the lines). if its not level, the center wont be the highest point anymore, and the bubble will be off center.

there u go. if it were a flat tube one would wonder why it wouldn
t just stay still at any position

#### dkozloski

##### Diamond Member
A pecision bubble level is a very expensive gadget. My L. S Starrett "Master Precision" level has a precisely ground to shape tube that is graduated in 0.0005in/ft of slope increments, is insulated to prevent errors from body heat and handling, and cost \$300 twenty years ago. The way to make a quick check on a level is to place it on a flat relatively level surface and observe how far the bubble is offset. Turn the level end for end and the offset should be the same.