Ancient Tools - The Plumbline - Scroll 1 一ノ巻

Modeled after French physicist J. B. L. Foucault's 1851 pendulum, the museum's pendulum demonstrates the axial rotation of the earth. The 240-pound brass, hollow bob is suspended by a 54-ft. steel cable from the ceiling of the 4th floor. Although the pendulum's vertical plane seems to change, in fact it remains fixed. What is actually moving is the floor, which rotates under the pendulum because of the Earth's rotation. As the Earth moves, the red markers -- arranged in a circle around an inlaid compass rose -- move into the path of the pendulum, and the bob knocks them over one by one.

From the Smithsonian site, interestingly.
Jim

I just read that some are powered by electromagnets. OK ,I promise I'm moving on.....as I prefer to not understand something more complicated.

Not sure IF this will be covered in the next episodes..but..

When I was laying out walls to form up (concrete) I would set up the "builder's Level to a "hub" on a batter board. Hub was anail, set by the surveyor. I needed the plumb bob to register on that hub, as close to the center on that nail head as I could get. Once the Level was set up, and still on the hub, I could "shoot the lines down the footer trench for the outside of the wall.

Doors: Not enough to check whether they are "wracked" out of square ( masons were good about that) but I needed to make sure they didn't lean in or open. Sometimes my 4' level was used, other times a small plumb bob. Same goes for window openings ( the company always hired out a window company crew) that we'd fir out for the installers. Again, sometimes a level, sometime the plumb bob....depended on how big the opening was, we could set up the bob, then add the blocking as needed to make the opening plumb. And...WHERE the window was supposed to be in that opening....

I'm a big fan of your Ancient Tools posts, Stan.

Keep the good history, application, and culture flowing!

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Originally Posted by Phillip Mitchell

I'm a big fan of your Ancient Tools posts, Stan.

Keep the good history, application, and culture flowing!

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Sure you don't want another thread comparing water stone grits to brands of toothpaste? Ha ha

I remember seeing some of the wildest acts to get things such as light fixtures centered in a room. Think about two workers with two step ladders one holding a tape at the corner of the ceiling and the other trying to get the room center marked on the ceiling of a vaulted overhead. Simple job with a plumb bob and an x on the floor. I was also taught to lay out complicated irregular roofs on the deck so you could check you layout with a plumb bob.
Jim

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Originally Posted by James Pallas

What happens if you stop the pendulum or swing a plumb bob?
Jim

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If it ain't swinging, it ain't a pendulum (by definition). Those who put up specimens of the Foucault Pendulum go to great pains to assure they don't stop swinging.

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Originally Posted by James Pallas

I remember seeing some of the wildest acts to get things such as light fixtures centered in a room. Think about two workers with two step ladders one holding a tape at the corner of the ceiling and the other trying to get the room center marked on the ceiling of a vaulted overhead. Simple job with a plumb bob and an x on the floor. I was also taught to lay out complicated irregular roofs on the deck so you could check you layout with a plumb bob.
Jim

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Ha ha! I know those guys! :D

The last time I used a plumbline was to resolve a disagreement between the interior designer and general contractor about the exact location of the "centers" of 15 meeting rooms in a very expensive, high-quality building nearing completion, and whether or not the light fixtures/air diffusers in the meeting rooms were in the center of the room, were centered on the table, and if both were centered on the large monitor on the wall. The meeting room tables were all custom made and very expensive ($45,000 ea) as were the monitor cabinets ($95,000 each not including monitors) and light fixtures (The Stakeholders were very particular about the quality (color/intensity/glare) of light, so we had Panasonic develop custom fixtures to Stakeholder's specs). Expensive and time-consuming to rework/replace. Of course, redoing the ceilings/pendant strip-lights/diffusers in 15 rooms is not chump change either. So the argument was worth at least $3 million US worst case.

With so much at stake, you can imagine how, by the time I arrived, everyone was very angry and frustrated, climbing ladders and stretching tape measures, while trying to look dignified and indignant at the same time. Nothing was getting done.

We located the centerline of the irregular-shaped rooms on the meeting room table of each room (tables are bolted to floor, so we couldn't layout on the floor) using a tape measure and my stringline (shifted diagonals), and then transferred that point to the ceilings with a plumbline I made from my stringline, a house key, and blue masking tape.

With this done, I took off my shoes and jumped onto the table, and precisely located the lights and diffusers with reference to the centerline. We then sketched plan of each room. This made it possible for us to go to each room with a dimensioned sketch, and quickly work out a compromise to make the rooms work, and keep the stakeholders happy without costing a lot of money and delaying the schedule. If I recall correctly (last November) the GC had to rework 3 ceilings, cut/shorten, one meeting table, and shift 4 more. The rest were acceptable as-is. There was enough blame to go around, so the finger-pointing stopped before it escalated. The analysis, inspections, and decisions took only 24 hours to work out, and the modifications were done within a week, but if I had kept my key and stringline in my pocket, and let the problem go its natural course, with each subcontractor taking his own laser measurements, and dinging the walls and furniture with ladders, it would have been very expensive, made everyone poorer, and delayed the Stakeholder's occupancy, making the Owner very unhappy.

We did an post-mortem and discovered that the Interior Designer (a very capable and hard-working lady) had sent drawings to the built-in cabinet maker and furniture maker that were then modified to accommodate things requested by the Owner later. Unfortunately, the updated drawings were not given to the cabinet/furniture subs, who fabed/installed per the old drawings. But they were not free of guilt because they failed to inform the ID, the GC, or me that the rooms differed from the drawings given them, but just installed their stuff and walked away.

This sort of confusion is almost unavoidable on a fast-track project with an insanely short schedule. But one thing I learned a long time ago was to not be timid or risk-averse (CYA), which just provides time for the problem to get bigger and the impacts more severe, but to get all the key players on the jobsite IMMEDIATELY, roll up the sleeves, and dive headfirst into finding solutions consistent with the Owner's goals. If this had happened in L.A. or N.Y., it would have been a nightmare of claims and lawsuits. Japan is a great place to work.

The final responsibility was the GC's, since it was Design/Build, and he was responsible for coordination, and the cabinet/furniture maker was his sub. The cabinet sub made the changes at no cost. The GC reworked the ceilings at no cost. The Owner never heard of the problem. The only impact on the Owner was that 3 meeting rooms were turned over a week later than originally planned, which was not a problem.

A lot of grief and expense was avoided because of a string, a key, and speedy action. Hail the Plumbline!

:) Great tale Stanley. I can picture it. Many eyes looking at the end of your key as it settles in from a gentle sway some of the eyes hit the floor as others look up thankfully. A site I have seen many times and have experienced an overwhelming sense of relief and great happiness about knowing the ways of the humble plumb bob.
Jim

Great story Stan. Can you say whether the GC was European, American or Japanese?
Fred

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Originally Posted by Frederick Skelly

Great story Stan. Can you say whether the GC was European, American or Japanese?
Fred

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Japanese. One of the Big Five GCs all of which are nicknamed "Super Zenecon."

Design/build, so the GC was ultimately at risk for the design.

Japanese GC's are great to work with, much easier than Americans or Brits. If it had been German contractor, I would have been forced to do something violent and illegal to get things resolved quickly.

Love this thread Stan! Looking forward to the next three.

So, you're going to 'string us along' until your next post. :rolleyes:

My grandpa had a neat plum bob. Too bad it did not end up in my hands.

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Originally Posted by Gary Cunningham

So, you're going to 'string us along' until your next post. :rolleyes:

My grandpa had a neat plum bob. Too bad it did not end up in my hands.

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I must be ”plumb” crazy.　:eek: