@bill93 How many thousandths are there in the difference of edge and center of the water column due to cohesion?
@lurker the water surface is a cup with a large enough area to measure at the center with the micrometer. And the meniscus may not be an issue as it would be the same at each cup. But I suspect it??s discussed in the documentation of the EDS System PWL. The description includes waiting at least 15 minutes for equilibrium to be achieved. It??s not a minor task.?ÿ
I saw one article on water level saying the author liked them but he had seen 3/8 inch error under poor conditions.
@bill93 Careful setup, micrometer reading of water height, proper kit and procedure.
Hilger Watts should do. Micrometer reading, etched glass cylinders. So I??m sure a carpenter can get 3/8, and I??m sure a machinist can use a HW properly.?ÿ
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https://www.wylerag.com/en/products/communicating-water-level/communicating-water-level/
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Oops.?ÿ 0.01 feet is the correct tolerance.?ÿ Getting 0.03 to 0.05 with standard methods making the 25 foot jump.
Personally, I think a 16-lb sledge can fix most any misalignment issue.
A recently calibrated 1 second robotic total station should do the job. ?ÿThe nice thing about a robot is they have a compensator for old eyes. ?ÿI??d turn multiple sets just because I can. ?ÿI??ve done a lot of construction staking and haven??t used a level in the last 25 years. ?ÿHaven??t had to pay out yet.
Knock on wood.?ÿ
I??d also epoxy mm scales on the walls and turn thru them. There??s a lot of ideas and methods. It comes down to site conditions as to how. 0.005 ft shouldn??t be unreasonable. 0.001 ft is different?ÿ
Oops.?ÿ 0.01 feet is the correct tolerance.?ÿ Getting 0.03 to 0.05 with standard methods making the 25 foot jump.
Personally, I think a 16-lb sledge can fix most any misalignment issue.
LOL
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It was like you dropped a bomb and walked away...now...oops...
.01',,,,,, well that's an entirely different animal. A good digital level, lots of checks and adjustments. Still probably not really going to be done, but way different than .001'.
This is a standard that got written into the specs by someone either not knowing what they were doing or transferring lots of liability to the surveyor. My advice is one I got from an engineering buddy of mine. Always say no, the structure didn't meet specs when you have to sign off. That way the liability is gone and they always build it anyway.
Te be crystal clear: 0.010 feet? That??s not rocket science. It??s not casual given it??s below grade and in a machine room. And what??s the accessibility? A vertical shaft? ?ÿConcrete steps?
Hilger Watts style water level now looks like a very viable option IMO when you get around floor level. I??ve done parking garage subsistence surveys with ceiling marks and N3. 0.01 foot is not hard.?ÿ
I don't understand the requirement to be within 0.001'.?ÿ Results with those tolerances are virtually impossible to repeat in the field and nothing will be built coming even close to those specs.?ÿ
@chris-bouffard He corrected the spec ?ÿ
Oops.?ÿ 0.01 feet is the correct tolerance.?ÿ
I was seeing specs being sent out for max tolerance of 1/4". The buildings got built, but if someone forced me to bet, I bet there's a 95% chance they didn't meet that spec.
@mightymoe construction error versus survey error is not what this thread is about.?ÿThe client requested elevation data within the building accurate yo 0.01 ft.
Nothing to do with a building getting built and whether its construction by the contractor adhered to data provided by survey.?ÿ
Actually the specs I'm referring to required that the surveyor sign off on each main element of the building that they were within 1/4". So yeah, it's about survey error and construction "error". The project got held up for years for some reason, but the building is there now, almost no chance that the spec was met. So yes this is about the thread.?ÿ
