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The MA thread - AKA Everyday Fan Vault Construction for Beginners.

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Rodpr

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Its all in the editing, Adam - which could make it frustrating (will he get it finished in time ...).

It would make a beautiful book though.
 

Adam W.

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I had a visit this evening from the computer technician upstairs.

The first thing he said when he set eyes on the drawing was "That looks like a Julia set".


















The Julia set video.
IkamusumeFan, CC


So we're off down the fractal and infinately repeating geometric shape rabbit hole, with the next stop the Fibonacci spiral.
 
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Adam W.

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I won't be in to show anyone around today if anyone was considering turning up.

Anyways, I did have a good peep into the fractal rabbit hole and decided it's best to wait for another time.

I am re-visiting my tenuous link with Frei Otto, Ted Happold and Michael Dickson and taking a good look at tensile structures, mobius strips, soap structures and assorted bendy wooden whatnots, to prove an idea that I have been mulling over after a conversation with an architect at the weekend.



Frei-Otto-Experimenting-with-Soap-Bubbles.png


Once the metalwork shop opens, I'll knock up a copy of one of these Frei Otto models, with the intention of trying to do someting.

As starter, the tension on the soap film is the same at all points and in all directions.
 
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Cooper

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Thank you Adam for so much of your time yesterday. I must say that I'm even more impressed by your work now and even keener to watch your progress. Really interested to see what you do with your soap bubbles.
Cheers
Martin
 

Adam W.

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Thanks for taking the time to come and visit, it was really nice to see you Martin.

It's the last day tomorrow and we shut at 13:00 for the big change over, so things are going to be quite hectic.
 

Adam W.

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A week off from thinking about vaults............

Spent the day with the casting technician making a mould for the Horse of Selene.

She is a very good mould maker who also works at the Royal College of Art and was loving the work, as she normally makes flat moulds, so this was a bit of a dream job for her and I got preferential treatment for the day.

We started by pouring a thin coat of silicone over the head to pick up all the detail.



IMG_4862.JPG




IMG_4867.JPG



Followed by layers with added thixo in the silicone to give the thin detail coat some structural strength.


IMG_4870.JPG




I think it looks rather fetching with an almost paisley finish.


IMG_4873.JPG


It's set to dry for the week and we'll start on making the split mould part of the process.

It's nice being able to call upon people who are experts in their field to get a masterclass in subjects like this.

Next week I'll start on the models for the vault.
 
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nickds1

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I won't be in to show anyone around today if anyone was considering turning up.

Anyways, I did have a good peep into the fractal rabbit hole and decided it's best to wait for another time.

I am re-visiting my tenuous link with Frei Otto, Ted Happold and Michael Dickson and taking a good look at tensile structures, mobius strips, soap structures and assorted bendy wooden whatnots, to prove an idea that I have been mulling over after a conversation with an architect at the weekend.



View attachment 120045

Once the metalwork shop opens, I'll knock up a copy of one of these Frei Otto models, with the intention of trying to do someting.

As starter, the tension on the soap film is the same at all points and in all directions.
Essentially, an analogue computer...
 

MARK.B.

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My eldest grand daughter would just love to have that pink horse head,she has a thing for pink at the moment:love:. Will you get a second chance with that mould or will you have to start over if it goes pear shaped:eek:
 

Adam W.

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The mould should be OK, as the head has form release on it. It's going to be a lightweight mould with a reinforced jacket over the silicone, as I'm taking it back home with me on the plane. I'll cast from it before it goes travelling, just in case.

The casting technician is very happy with the progress so far and I have every confidence in her ability to make a decent mould to cast from. I'm only going to cast three heads and the first one will probably be destroyed.
 

Cooper

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Is it a split mould? In the picture of pouring on the first coat, it looks as though she is only working on the side she is standing. Otherwise how do you get the head out of the mould. Lots of fun.
It must really help having expert assistance, far less chance of stray bubbles.
Good luck
Martin
 

Adam W.

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It's going to be a split mould and the back is covered the same way as the front. Quite what the next few steps are going to be, is anyones guess and I'll find out on Thursday at the next installment.

She knows what she's doing which is good enough for me. I'll worry about the vault and she can worry about the mould making.
 

Adam W.

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Back to vaulting......

Using the principals of Hookes law, I've been making scale plaster models of the optimum load path for the vault. They seem to work well and it's good fun making them. They are not as accurate as a chain, but they are visually pleasing because they are so thin (3-4mm) and can take a load (500g of loading so far).

IMG_4879.JPG


The one standing, represents the correct span and the arch has the same length of circumference as the vault. This doesn't look like the model at all and is incorrect, as it's too steep and the curvature representing the load path lies outside the thickness of the masonry vault. So I need to make one with a greater span and a longer circumference to produce a shallower vault.

The second one at the front represents the shallowest curve which can be contained within the masonry, but I think it's too shallow and the span is too great, so I'll make a third (the Goldilocks arch) which will be steeper with a shorter span.


P1850579.JPG



My plan is to try to estimate the minimum thickness of the masonry wall required to support the vault, using the difference between the span of the arches. I'll then compare this with the actual wall thickness (which I don't know at the moment) to see if the thickness can be calculated with any accuracy using a piece of rope or chain. I'll allow for a minimum masonry thickness of 9" (about 3"on the model) at the apex of the vault to produce a steeper catenary.

All this has nothing to do with the timber model, but I want to fully understand the masonry vault and produce some physical research to impress the judges at my first major assessment in a couple of weeks. I'm also interested to see if a practical vault can be designed using geometry and a chain, but without any mathematical calculations.

So far I've shown that it can be designed using a compass and geometry and two measurements, but can I prove that it will stand up under load ?
 

Droogs

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Hanging chains are how Goudi designed the Sagrada Familia, his workshop models are on display in the vaults of the cathedral. Very interesting watching you go through this process Adam. Enjoying it very much. Say heloo to Karup and Herning for me if you are passing (had lots of fun there in my youth)
 

Inspector

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The thickness of the masonry could be checked with an ultrasonic thickness gauge. It is non destructive so no poking holes etc into the structure. Perhaps a local engineering firm would volunteer to measure for you in the interest of historical knowledge. Trick would be finding one. If you could you could verify your calculations against the actual readings.
Concrete Thickness Gauge Might be able to recommend someone near you.
Concrete Thickness Gauge | PCTE

Pete
 

Adam W.

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Model #3 and I think I can roughly estimate the thickness of the masonry required at the wall to be.......

IMG_4883.JPG




16" with a 10% margin for error and I don't know the thickness of the top of the vault. The top of my plaster curve comes out at 10", but the masonry could be thinner, which would make the walls thicker. Going through all this leads me to believe that the thickness of the walls could be calculated with a chain using a drawing containing the whole of the curve including the tas de charge.

The master mason is going to measure the thickness of the interior masonry wall for me on Thursday, if she remembers.

Out of interest, the first plaster curve can now take a point load of 1kg at its apex. I'll test it to destruction at the end of the MA.
 
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Droogs

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The one at the back reminds me of those medival Spanish roofs made with tiles stuck together on edge. Apparently once you have 3 or 4 courses they are remarkably strong.
 

Adam W.

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They used something similar on the NY Metro too. I think it was an Italian company which made those.
 

nickds1

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Years ago Grand Designs did a house based on this technique at Marden, just a few miles from where we live - cycle past it frequently. It did collapse at one point during the build.


Looked a bit shabby last time I saw it (earlier this year).
 
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Adam W.

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I am happy to report that I underestimated the thickness of the masonry, which is now measured as roughly 22". This leads me to believe that more experimentation with plaster is required on Monday.

I am also happy to report that the first plaster model can now easily support a point load consisting of a bucket of screws, an 18" tenon saw and a pair of pliers stacked on top of each other.
 

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