Just loosen up those tolerances....
Bam! Solved!
Generally, the engineer hires an out of town surveyor that will tell them they can hit the tolerance, and then no questions are asked.
40 thousandths of an inch is more than 3 thousandths of a foot which is worse than he's doing with the total station.
I think it is about the same??ÿ (1/12)*.040=0.00333
I checked it three different ways. At age 76, I try not to shoot from the hip, 'cause I'm not always sure where my hip is.
I should stop shooting from the hip myself. I am glad you caught me putting my foot in my mouth. I was out staking curb and gutter I just hope they don??t find that stake I was figuring on and it was cold for me to brake out my hillbilly calculator today with ice still on the ground. ?ÿBut the mississippi never leaves the boy. ????. ?ÿRunning levels in tight spots is challenging. Especially at short distance. ?ÿI ran three wires through a va hospital once back in The 90??s . We had god overall closure but the error showed up when running the other loops within the building. Lots of head scratching. ?ÿNone of the tolerances were as tight as what this job needs. I still say laser tracker is a no brainer. ?ÿ5 years ago I would have not even mentioned one or did I know what one was. ?ÿAfter using one for a few years and wrapping my brain around understanding the terminology which can be confusing for a surveyor at first. Because the verbiage is identical to some we use but not exactly the same. Once the light bulb ??? came on I was amazed at what I could achieve. In the right environment only though. ?ÿ
@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.
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!
?ÿ
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
@brad-ott I've seen suspended accoustical tile ceiling hung using that method.
Andy
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
@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?
