Does a House's LEVEL Change, Day to Day?
 

I'm getting ready to set some ceramic tiles on my kitchen wall for a
backsplash. A few days ago I screwed a couple of very straight 5'
steel bars end to end horizontally along the wall studs, to serve as a
ledge to mount the first row of tiles on. I was very careful to get
the two bars' ends completely flush with each other and level, using a
good accurate 48" Johnson level. I checked their level later that
night, and again the next day. Both bars were dead-on level.
Yesterday I checked their level one more time prior to beginning the
tiling and guess what: they're both off somewhere between an eight and
a quarter of an inch.

I set the level at the same place on the bars each time, and used the
same side of the level. The bars can't slip....they're still securely
screwed to the studs behind the drywall. And their ends are still
flush with each other, so I have a good 10' straight edge along the
wall. But what's up with the changing level?

This house is a 50 year old single story brick veneer, built on a
concrete slab in West Texas. Is it normal for houses or individual
walls to shift that much from day to day? Maybe due to temperature
variations?

Does a House's LEVEL Change, Day to Day?
 

In article , Josh wrote:
I'm getting ready to set some ceramic tiles on my kitchen wall for a
backsplash. A few days ago I screwed a couple of very straight 5'
steel bars end to end horizontally along the wall studs, to serve as a
ledge to mount the first row of tiles on. I was very careful to get
the two bars' ends completely flush with each other and level, using a
good accurate 48" Johnson level. I checked their level later that
night, and again the next day. Both bars were dead-on level.
Yesterday I checked their level one more time prior to beginning the
tiling and guess what: they're both off somewhere between an eight and
a quarter of an inch.

I set the level at the same place on the bars each time, and used the
same side of the level. [remainder snipped]

Explanation: you may have used the same *side* of the level each time, but
turned it end-for-end for the second measurement.

Your level isn't as accurate as you think it is. Put the level on the bars,
then turn it end-for-end, keeping it parallel to the floor, and check again.
I'll bet it reads level one way, and not the other.

Does a House's LEVEL Change, Day to Day?
 

Josh wrote:
I'm getting ready to set some ceramic tiles on my kitchen wall for a
backsplash. A few days ago I screwed a couple of very straight 5'
steel bars end to end horizontally along the wall studs, to serve as a
ledge to mount the first row of tiles on. I was very careful to get
the two bars' ends completely flush with each other and level, using a
good accurate 48" Johnson level. I checked their level later that
night, and again the next day. Both bars were dead-on level.
Yesterday I checked their level one more time prior to beginning the
tiling and guess what: they're both off somewhere between an eight and
a quarter of an inch.

I set the level at the same place on the bars each time, and used the
same side of the level. The bars can't slip....they're still securely
screwed to the studs behind the drywall. And their ends are still
flush with each other, so I have a good 10' straight edge along the
wall. But what's up with the changing level?

This house is a 50 year old single story brick veneer, built on a
concrete slab in West Texas. Is it normal for houses or individual
walls to shift that much from day to day? Maybe due to temperature
variations?

Why steel bars? Perhaps they expanded enough to force one end up or
down a little bit?

Does a House's LEVEL Change, Day to Day?
 

Josh wrote:
-snip-
the two bars' ends completely flush with each other and level, using a
good accurate 48" Johnson level.

By accurate- do you mean you checked the level just before using? You
swapped the ends, and the level was the same? [being careful to wipe
the bottom both times so some errant little chip or whatever wasn't
throwing you off]

-snip-
Yesterday I checked their level one more time prior to beginning the
tiling and guess what: they're both off somewhere between an eight and
a quarter of an inch.

[first off- for my money, there is a world of difference between 1/8
and 1/4 in a tile job. You should be thinking in 16ths at least-
and 32ds will make it look that much better]

If your house settled 1/4 inch in 4' overnight- you might want to put
off tiling until you find out what your problem is. If you were
in MN,[40below zero-- F. . .brrrr] then maybe it frost heave could do
it-- and if it did- then that wall isn't a good place for tiles.

I don't think it was that cold in W TX- so I would suspect
1. level got whacked- or
2.operator error.
3. Serious trouble that you need to verify and correct before you tile
anything.

-snip-

This house is a 50 year old single story brick veneer, built on a
concrete slab in West Texas. Is it normal for houses or individual
walls to shift that much from day to day? Maybe due to temperature
variations?

Jim

Does a House's LEVEL Change, Day to Day?
 

On Jan 3, 9:52*pm, Josh wrote:
I'm getting ready to set some ceramic tiles on my kitchen wall for a
backsplash. *A few days ago I screwed a couple of very straight 5'
steel bars end to end horizontally along the wall studs, to serve as a
ledge to mount the first row of tiles on. *I was very careful to get
the two bars' ends completely flush with each other and level, using a
good accurate 48" Johnson level. *I checked their level later that
night, and again the next day. *Both bars were dead-on level.
Yesterday I checked their level one more time prior to beginning the
tiling and guess what: they're both off somewhere between an eight and
a quarter of an inch.

I set the level at the same place on the bars each time, and used the
same side of the level. *The bars can't slip....they're still securely
screwed to the studs behind the drywall. *And their ends are still
flush with each other, so I have a good 10' straight edge along the
wall. *But what's up with the changing level?

This house is a 50 year old single story brick veneer, built on a
concrete slab in West Texas. *Is it normal for houses or individual
walls to shift that much from day to day? Maybe due to temperature
variations?

If your house shifted 1/4" overnight you would of heard walls
creaking, maybe plaster cracking, doors and windows would not operate
the same, some windows might not even open easily and some doors might
catch on the frame, I jacked up a few places and thats what happened.
Remeasure it.

Does a House's LEVEL Change, Day to Day?
 

Josh wrote the following:
I'm getting ready to set some ceramic tiles on my kitchen wall for a
backsplash. A few days ago I screwed a couple of very straight 5'
steel bars end to end horizontally along the wall studs, to serve as a
ledge to mount the first row of tiles on. I was very careful to get
the two bars' ends completely flush with each other and level, using a
good accurate 48" Johnson level. I checked their level later that
night, and again the next day. Both bars were dead-on level.
Yesterday I checked their level one more time prior to beginning the
tiling and guess what: they're both off somewhere between an eight and
a quarter of an inch.

I set the level at the same place on the bars each time, and used the
same side of the level. The bars can't slip....they're still securely
screwed to the studs behind the drywall. And their ends are still
flush with each other, so I have a good 10' straight edge along the
wall. But what's up with the changing level?

This house is a 50 year old single story brick veneer, built on a
concrete slab in West Texas. Is it normal for houses or individual
walls to shift that much from day to day? Maybe due to temperature
variations?


Where you at the same 'level' of sobriety both days?

--

Bill
In Hamptonburgh, NY
In the original Orange County. Est. 1683
To email, remove the double zeroes after @

Does a House's LEVEL Change, Day to Day?
 

On Jan 4, 10:52*am, willshak wrote:
Josh wrote the following:





I'm getting ready to set some ceramic tiles on my kitchen wall for a
backsplash. *A few days ago I screwed a couple of very straight 5'
steel bars end to end horizontally along the wall studs, to serve as a
ledge to mount the first row of tiles on. *I was very careful to get
the two bars' ends completely flush with each other and level, using a
good accurate 48" Johnson level. *I checked their level later that
night, and again the next day. *Both bars were dead-on level.
Yesterday I checked their level one more time prior to beginning the
tiling and guess what: they're both off somewhere between an eight and
a quarter of an inch.

I set the level at the same place on the bars each time, and used the
same side of the level. *The bars can't slip....they're still securely
screwed to the studs behind the drywall. *And their ends are still
flush with each other, so I have a good 10' straight edge along the
wall. *But what's up with the changing level?

This house is a 50 year old single story brick veneer, built on a
concrete slab in West Texas. *Is it normal for houses or individual
walls to shift that much from day to day? Maybe due to temperature
variations?

Where you at the same 'level' of sobriety both days?

--

Bill
In Hamptonburgh, NY
In the original Orange County. Est. 1683
To email, remove the double zeroes after @- Hide quoted text -

- Show quoted text -

Or maybe he needs new glasses.

Does a House's LEVEL Change, Day to Day?
 

"Josh" wrote in message
...
I'm getting ready to set some ceramic tiles on my kitchen wall for a
backsplash. A few days ago I screwed a couple of very straight 5'
steel bars end to end horizontally along the wall studs, to serve as a
ledge to mount the first row of tiles on. I was very careful to get
the two bars' ends completely flush with each other and level, using a
good accurate 48" Johnson level. I checked their level later that
night, and again the next day. Both bars were dead-on level.
Yesterday I checked their level one more time prior to beginning the
tiling and guess what: they're both off somewhere between an eight and
a quarter of an inch.

I set the level at the same place on the bars each time, and used the
same side of the level. The bars can't slip....they're still securely
screwed to the studs behind the drywall. And their ends are still
flush with each other, so I have a good 10' straight edge along the
wall. But what's up with the changing level?

This house is a 50 year old single story brick veneer, built on a
concrete slab in West Texas. Is it normal for houses or individual
walls to shift that much from day to day? Maybe due to temperature
variations?

West Texas uh. Check this out.....Paul

http://www.childersleveling.com/mustknow.htm

Does a House's LEVEL Change, Day to Day?
 

On Jan 3, 9:52*pm, Josh wrote:
I'm getting ready to set some ceramic tiles on my kitchen wall for a
backsplash. *A few days ago I screwed a couple of very straight 5'
steel bars end to end horizontally along the wall studs, to serve as a
ledge to mount the first row of tiles on. *I was very careful to get
the two bars' ends completely flush with each other and level, using a
good accurate 48" Johnson level. *I checked their level later that
night, and again the next day. *Both bars were dead-on level.
Yesterday I checked their level one more time prior to beginning the
tiling and guess what: they're both off somewhere between an eight and
a quarter of an inch.

I set the level at the same place on the bars each time, and used the
same side of the level. *The bars can't slip....they're still securely
screwed to the studs behind the drywall. *And their ends are still
flush with each other, so I have a good 10' straight edge along the
wall. *But what's up with the changing level?

This house is a 50 year old single story brick veneer, built on a
concrete slab in West Texas. *Is it normal for houses or individual
walls to shift that much from day to day? Maybe due to temperature
variations?


I had a house boat that used to do that all the time.

Does a House's LEVEL Change, Day to Day?
 

Josh wrote:
I'm getting ready to set some ceramic tiles on my kitchen wall for a
backsplash. A few days ago I screwed a couple of very straight 5'
steel bars end to end horizontally along the wall studs, to serve as a
ledge to mount the first row of tiles on. I was very careful to get
the two bars' ends completely flush with each other and level, using a
good accurate 48" Johnson level. I checked their level later that
night, and again the next day. Both bars were dead-on level.
Yesterday I checked their level one more time prior to beginning the
tiling and guess what: they're both off somewhere between an eight and
a quarter of an inch.

I set the level at the same place on the bars each time, and used the
same side of the level. The bars can't slip....they're still securely
screwed to the studs behind the drywall. And their ends are still
flush with each other, so I have a good 10' straight edge along the
wall. But what's up with the changing level?

This house is a 50 year old single story brick veneer, built on a
concrete slab in West Texas. Is it normal for houses or individual
walls to shift that much from day to day? Maybe due to temperature
variations?

I'd be more inclined to suspect the different expansion rates of the
steel bars and wall structure during temperature swings. Most people use
an eyeball-straight 1x4 for what you are doing. Not like you are lining
up laser optics or anything, here. Lay a marble on the bar, and see
which way it wants to roll.

Having said that, this is Texas, and the laws of physics on your
infamous clay soil are different at times. Had any rain or big temp
swings outside?

I'd not lose a lot of sleep over it. Most people set the counter and
upper cabinets before they set the backsplash, and fudge as needed so it
looks right. Eyes looking at it will key off the back edge of counter
and bottom edge of upper cabinets. Tile is seldom gauge-block uniform in
size and square anyway.

--
aem sends...

Does a House's LEVEL Change, Day to Day?
 

In article
,
RickH wrote:

On Jan 3, 9:52*pm, Josh wrote:
I'm getting ready to set some ceramic tiles on my kitchen wall for a
backsplash. *A few days ago I screwed a couple of very straight 5'
steel bars end to end horizontally along the wall studs, to serve as a
ledge to mount the first row of tiles on. *I was very careful to get
the two bars' ends completely flush with each other and level, using a
good accurate 48" Johnson level. *I checked their level later that
night, and again the next day. *Both bars were dead-on level.
Yesterday I checked their level one more time prior to beginning the
tiling and guess what: they're both off somewhere between an eight and
a quarter of an inch.

I set the level at the same place on the bars each time, and used the
same side of the level. *The bars can't slip....they're still securely
screwed to the studs behind the drywall. *And their ends are still
flush with each other, so I have a good 10' straight edge along the
wall. *But what's up with the changing level?

This house is a 50 year old single story brick veneer, built on a
concrete slab in West Texas. *Is it normal for houses or individual
walls to shift that much from day to day? Maybe due to temperature
variations?


I had a house boat that used to do that all the time.


You must store your grog evenly on both sides of the galley to keep an
even keel.

-Frank

--
Here's some of my work:
http://www.franksknives.com/

Does a House's LEVEL Change, Day to Day?
 

As for why I used the steel bars: They were the straightest objects I
had on hand, plus they already had a lot slots & holes in them so I
could run a screw through them and into the studs easily.

Anyway, I did as many of you suggested and swapped the ends of the
level. Sure enough, both bars are off 1/8" one way and dead level
when the level's ends are rotated. Question is: which is correct?

I thought I could determine the "accurate" end by checking the bars'
level with a couple of 24" Craftsman levels I have. One of shorter
levels showed the same thing the 48" level showed (dead on one way and
off 1/8" the other) and the other level showed a 1/8" error each, only
exact opposite depending on which way the level is orienated.

Guess I'll go with the longer level, and be careful to keep it
orientated the same way all the time. Like someone above said, tile
rows don't have to be laser-precise level.

Does a House's LEVEL Change, Day to Day?
 

On Jan 4, 7:09*pm, Josh wrote:
As for why I used the steel bars: *They were the straightest objects I
had on hand, plus they already had a lot slots & holes in them so I
could run a screw through them and into the studs easily.

Anyway, I did as many of you suggested and swapped the ends of the
level. *Sure enough, both bars are off 1/8" one way and dead level
when the level's ends are rotated. *Question is: which is correct?

I thought I could determine the "accurate" end by checking the bars'
level with a couple of 24" Craftsman levels I have. *One of shorter
levels showed the same thing the 48" level showed (dead on one way and
off 1/8" the other) and the other level showed a 1/8" error each, only
exact opposite depending on which way the level is orienated.

Guess I'll go with the longer level, and be careful to keep it
orientated the same way all the time. *Like someone above said, tile
rows don't have to be laser-precise level.

You need to check your levels and discard ones that are off
calibration. Find a rigid flat surface longer than the level. Place
the level on it, check the bubble and note the exact location
(centering is not necessary). Reverse the level (180 degrees). The
bubble should be in exactly the same location. If the level passes
this test it is OK to use it for your projects. If it fails, put it
on the curb and get a decent level such as Johnson or similar.
Considering the frustration you are having with your work, it would be
prudent to buy and use a laser level. Prices range from $20 to $400+
depending on what you want, but the cheapies from Harbor Freight are
perfectly accurate for tile work and the like.
Even a line level will do a good job. The level hangs from the center
of the line and needs two people to get it right. When anchored at one
end of the line, the other end is raised and kept fairly tight until
the bubble is perfectly centered. Framers and carpenters often use
these low cost tools for lengthy measurements. They are usually within
1/8" or so of a laser level line.

Joe

Joe

Does a House's LEVEL Change, Day to Day?
 

Joe wrote:
On Jan 4, 7:09 pm, Josh wrote:
As for why I used the steel bars: They were the straightest objects I
had on hand, plus they already had a lot slots & holes in them so I
could run a screw through them and into the studs easily.

Anyway, I did as many of you suggested and swapped the ends of the
level. Sure enough, both bars are off 1/8" one way and dead level
when the level's ends are rotated. Question is: which is correct?

I thought I could determine the "accurate" end by checking the bars'
level with a couple of 24" Craftsman levels I have. One of shorter
levels showed the same thing the 48" level showed (dead on one way and
off 1/8" the other) and the other level showed a 1/8" error each, only
exact opposite depending on which way the level is orienated.

Guess I'll go with the longer level, and be careful to keep it
orientated the same way all the time. Like someone above said, tile
rows don't have to be laser-precise level.

You need to check your levels and discard ones that are off
calibration. Find a rigid flat surface longer than the level. Place
the level on it, check the bubble and note the exact location
(centering is not necessary). Reverse the level (180 degrees). The
bubble should be in exactly the same location.

You sure about that?
Passing your test suggests that the level is ok.
Failing your test suggests that the level is bad OR the test
surface is not level.

If the level passes
this test it is OK to use it for your projects. If it fails, put it
on the curb and get a decent level such as Johnson or similar.
Considering the frustration you are having with your work, it would be
prudent to buy and use a laser level. Prices range from $20 to $400+
depending on what you want, but the cheapies from Harbor Freight are
perfectly accurate for tile work and the like.
Even a line level will do a good job. The level hangs from the center
of the line and needs two people to get it right. When anchored at one
end of the line, the other end is raised and kept fairly tight until
the bubble is perfectly centered. Framers and carpenters often use
these low cost tools for lengthy measurements. They are usually within
1/8" or so of a laser level line.

Joe

Joe

Does a House's LEVEL Change, Day to Day?
 

"mike" wrote in message
...

You need to check your levels and discard ones that are off
calibration. Find a rigid flat surface longer than the level. Place
the level on it, check the bubble and note the exact location
(centering is not necessary). Reverse the level (180 degrees). The
bubble should be in exactly the same location.

You sure about that?
Passing your test suggests that the level is ok.
Failing your test suggests that the level is bad OR the test
surface is not level.

The surface doesn't need to be level.

If the bubble is not in the same place in both directions, it's definately
defective (or has debris interfering).

He is not suggesting that the bubble should be centered at all.

Does a House's LEVEL Change, Day to Day?
 

Joe wrote:
(snip)

You need to check your levels and discard ones that are off
calibration. Find a rigid flat surface longer than the level. Place
the level on it, check the bubble and note the exact location
(centering is not necessary). Reverse the level (180 degrees). The
bubble should be in exactly the same location. If the level passes
this test it is OK to use it for your projects. If it fails, put it
on the curb and get a decent level such as Johnson or similar.


1. Even a level with broken bubbles makes a pretty good and handy
expendable straight edge. Way too useful to put in the trash.
2. Some levels are adjustable.
3. For DIY use, as long as one bubble is good, just label as needed with
a Sharpie, so you know which one to use.
4. Precision levels are damn expensive. My 83 YO father has used the
same wooden brass-edged 4-foot level (Stanley?) for 40-some years, and
it is still plenty accurate enough for residential construction. I use a
5-buck 3-foot garage sale aluminum level, M-D brand, and it reads the
same both directions. If you are making money with a tool, it is worth
it to get top quality and replace it if less than perfect. If you are
just puttering around the house, you can easily get by with something
lower down the food chain.

--
aem sends...

Does a House's LEVEL Change, Day to Day?
 

On Jan 4, 7:09*pm, Josh wrote:
As for why I used the steel bars: *They were the straightest objects I
had on hand, plus they already had a lot slots & holes in them so I
could run a screw through them and into the studs easily.

Anyway, I did as many of you suggested and swapped the ends of the
level. *Sure enough, both bars are off 1/8" one way and dead level
when the level's ends are rotated. *Question is: which is correct?

I thought I could determine the "accurate" end by checking the bars'
level with a couple of 24" Craftsman levels I have. *One of shorter
levels showed the same thing the 48" level showed (dead on one way and
off 1/8" the other) and the other level showed a 1/8" error each, only
exact opposite depending on which way the level is orienated.

Guess I'll go with the longer level, and be careful to keep it
orientated the same way all the time. *Like someone above said, tile
rows don't have to be laser-precise level.

If you have now figured out that there are some errors with the
levels, why not fix them all so that they give the same reading no
matter which way they are placed. Most levels can be adjusted by
shifting the vials slightly.

Does a House's LEVEL Change, Day to Day?
 

Me wrote:
"mike" wrote in message
...

You need to check your levels and discard ones that are off
calibration. Find a rigid flat surface longer than the level. Place
the level on it, check the bubble and note the exact location
(centering is not necessary). Reverse the level (180 degrees). The
bubble should be in exactly the same location.
You sure about that?
Passing your test suggests that the level is ok.
Failing your test suggests that the level is bad OR the test
surface is not level.

The surface doesn't need to be level.

If the bubble is not in the same place in both directions, it's definately
defective (or has debris interfering).

He is not suggesting that the bubble should be centered at all.

Neither am I...unless you expect the level to be "true".


Try this.
Go up on your sloped roof and stick the level in the direction of
maximum slope.
Mark the position of the bubble.
Rotate the level 180 degrees.
Mark the location of the bubble.
If they're in the same position, report back.

The ONLY surface that puts the bubble in the same position
regardless of level direction is a LEVEL SURFACE.

On a LEVEL SURFACE, there is NO rotation of the level that
makes the bubble go to a different place.

Your level is "calibrated" IF you have a perfectly level surface
AND the bubble sits in the CENTERED position.

Does a House's LEVEL Change, Day to Day?
 

On Mon, 04 Jan 2010 21:55:06 -0500, aemeijers wrote:
4. Precision levels are damn expensive. My 83 YO father has used the
same wooden brass-edged 4-foot level

Hmm, I have one like that - scored off Freecycle. I don't know how old
it is exactly, but it's a wonderful bit of construction (and certainly
"old"). Unfortunately, it's 4000 miles away from where I live now, and I
don't know if it'd be economical to ship (vs. just buying something
equivalent locally) :-(

cheers

Jules

Does a House's LEVEL Change, Day to Day?
 

In article , wrote:
The ONLY surface that puts the bubble in the same position
regardless of level direction is a LEVEL SURFACE.

I think the disagreement here stems from different interpretations of the
phrase "in the same position" -- the same position relative to the surface
being tested, or the same position relative to a specific end of the level.

You're thinking the latter; everyone else here is thinking the former.

Designate the ends of the level as "A" and "B". Place the level on any surface
you wish, with end "A" on your left and end "B" on your right. If the surface
slopes upward from left to right, the bubble will be off-center to the right,
toward end "B".

Now reverse the level left-right, so that end "B" is on the left and end "A"
is on the right, and replace it on the surface in the same position as before.

If the bubble is off-center to the right by the same distance it was before,
the level is true. That's what's meant by "in the same position": relative to
the surface being tested. It doesn't matter that it's now off-center toward
end "A" instead of "B" as it was before.

Does a House's LEVEL Change, Day to Day?
 

Do NOT use that level. The level is out of calibration. If you
cannot reverse the level, the bubble is not within spec. It is
almost impossible for an excellent craftsman with a very good hand
level to close around any room. It won't happen with a level out
of calibration. You are compounding an error.

This is one time to consider a water level (cheap) or to borrow a
laser.


--
______________________________
Keep the whole world singing . . . .
DanG (remove the sevens)




"Josh" wrote in message
...
As for why I used the steel bars: They were the straightest
objects I
had on hand, plus they already had a lot slots & holes in them
so I
could run a screw through them and into the studs easily.

Anyway, I did as many of you suggested and swapped the ends of
the
level. Sure enough, both bars are off 1/8" one way and dead
level
when the level's ends are rotated. Question is: which is
correct?

I thought I could determine the "accurate" end by checking the
bars'
level with a couple of 24" Craftsman levels I have. One of
shorter
levels showed the same thing the 48" level showed (dead on one
way and
off 1/8" the other) and the other level showed a 1/8" error
each, only
exact opposite depending on which way the level is orienated.

Guess I'll go with the longer level, and be careful to keep it
orientated the same way all the time. Like someone above said,
tile
rows don't have to be laser-precise level.

Does a House's LEVEL Change, Day to Day?
 

On Jan 5, 7:57*am, (Doug Miller) wrote:
In article , wrote:
The ONLY surface that puts the bubble in the same position
regardless of level direction is a LEVEL SURFACE.

I think the disagreement here stems from different interpretations of the
phrase "in the same position" -- the same position relative to the surface
being tested, or the same position relative to a specific end of the level.

You're thinking the latter; everyone else here is thinking the former.

Designate the ends of the level as "A" and "B". Place the level on any surface
you wish, with end "A" on your left and end "B" on your right. If the surface
slopes upward from left to right, the bubble will be off-center to the right,
toward end "B".

Now reverse the level left-right, so that end "B" is on the left and end "A"
is on the right, and replace it on the surface in the same position as before.

If the bubble is off-center to the right by the same distance it was before,
the level is true. That's what's meant by "in the same position": relative to
the surface being tested. It doesn't matter that it's now off-center toward
end "A" instead of "B" as it was before.

I always use paper shims under the "low" end of the surface that I am
using as a "level" reference. Once I get the surface level, then it
does not matter which position I use to place the measuring level, it
shoud be off by the same amount no matter which side is to the "left.
Once I am sure the surface is level using the shims, I then adjust the
vial so that the bubble is in the middle. Once that is done, I go
back to the original slightly unlevel surface and see that the vial
indicates the same amount of unlevelness no matter which end of the
level is to the left.