Only done a few industrial factory layouts.?ÿ Handled all the exterior staking, precise concrete pads and ibeam column penetrations, and spent several days doing precise levels using a parallel plate micrometer and invar rods?ÿ after the pad had stabilized to brass disks set in the pad and stable benchmarks?ÿ surrounding the building, to 1mm.?ÿ After that, I was gone.?ÿ A metrology outfit took over and did all the location/alignment work of the machinery, baseplates etc., inside the building.?ÿ I observed them at work aligning an electric motor to a hundred ton sheet metal press, etc., and their gear was exquisite;?ÿ they claimed they could get shaft alignments in 3-D down to 1 or 2 thousands of an inch.?ÿ Way beyond my pay grade.
@dmyhill?ÿ
Indeed, @holy-cow and @olemanriver each gave only one significant digit, so comparing beyond that accuracy is improper.
Edit: Actually, @olemanriver gave two significant digts; the trailing zero is significant. But comparing 0.003 to 0.0033 is not proper.
But the planning department assures me that 0.0033 is OVER 0.003, so I cannot build my mansion!
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If you start with significant digits informed by tools we use, I am guessing that most of us cannot produce the precision required. We are essentially taking a butter knife to eye surgery with a 5" total station rated at +/- 0.01 + PPM attempting to get 0.001' measurements.
So many questions about the confines of the plant. If there??s a vertical shaft I??d hang a calibrated chain (tape) and read it by a level to get the big drop. A manual level N2/N3 might serve in vibration. I have used N3 on bridge crossings, preferred compared to Jena or Zeiss. The may be an issue of minimum focus distance if it??s cramped.?ÿ
And with any success, repeat as many times as the stats indicate to achieve confidence region.?ÿ
Hired this from Kara when doing industrial layouts in Illinois. Amazing piece of kit that will get you the tolerances required.?ÿ
https://www.karaco.com/optical-tooling/automatic-levels/freiberger-fg005-automatic-level-metric/
dyslexic
It's Lisdexic. Just sayin.
🙂
N
?ÿ I came back and added a zero to the end of the elevation and left.
How are anybody gonna find 0.005' of error?
The construction guys are most certainly going to be concerned. But, if they get it within 0.01', they are going home.
N
A water tube level is cheap and can work around corners
?ÿThe accuracy seriously degrades if the fluid is not all at the same temperature (e.g., sun/shade, indoor/outdoor) or there are air bubbles.
I saw this. So after establishing the the big 25 ft drop, this may work on the equipment level.?ÿ
http://www.precisiontools.biz/tools2/pwl/
@dmyhill?ÿ
Speaking of significant digits, and how they are insignificant to most people, when I went to make my sandwich this morning I saw the SWMBO had bought some fresher cold cuts and the one package seemed larger than normal, so I looked at the tag to see how much she bought. The weight was 1.005 lbs., my immediate thought was WHY?, out to the .01 lb. is a bit ridiculous, in my opinion. Does that extra .005 net them another $.01 or something. I don't know if this county has a weights & measures department (most likely, or is that one of the first to suffer from budget cuts) but if there is one, are they really certifying to that accuracy? if so, WHY?
@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