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Old 2019-10-17, 22:18   #12
jasong
 
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Quote:
they decided on a design with 126 blocks for their model, which was built at a scale of 1 to 500 (making it about 32 inches long). Then the individual blocks were made on a 3-D printer, taking about six hours per block to produce.
Me:" Hey, can I use the 3d printer?"

Person 2: "Nah, man, it's busy, come back in a couple weeks."

I then fail a course because of an "awesome experiment."

Last fiddled with by LaurV on 2019-10-18 at 04:38 Reason: fix quote tag
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Old 2019-10-18, 04:43   #13
LaurV
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Quite a slow printer...
(or extremely bad design of the manufacturing 3D files)
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Old 2019-10-18, 07:35   #14
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There is a principal in arch design. A half circle arch will distribute the force of its load perpendicularly downward on a column if present and is a stable structure. A shallower arch has the issue of exerting part of the force sideways and the shallower the arch the less stable it will be. In architecture this is addressed by having an array of shallow arches side by side to cancel out the sideway forces. Another issue is the shallower the arch the greater the leverage of the force of the load at the base, reaching a theoretical infinite leverage for an infinitely incompressible (but flexible) flat arch.

Last fiddled with by a1call on 2019-10-18 at 07:39
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Old 2019-10-18, 18:46   #15
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Quote:
Originally Posted by Uncwilly View Post
Why then are there so many differing gauges in the same areas? Not all carriages were of the same width.
https://en.wikipedia.org/wiki/Track_gauge
Uh, Roman war horses two abreast didn't pull mine cars through mine tunnels dug by hand?
https://www.lcas-astronomy.org/artic...=miscellaneous
A few percent variation in gauge would matter less on wheels in rounded ruts than it would on narrow flanged wheels riding narrow metal rails.
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Old 2019-10-19, 06:31   #16
xilman
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Quote:
Originally Posted by kriesel View Post
Uh, Roman war horses two abreast didn't pull mine cars through mine tunnels dug by hand?
https://www.lcas-astronomy.org/artic...=miscellaneous
A few percent variation in gauge would matter less on wheels in rounded ruts than it would on narrow flanged wheels riding narrow metal rails.
Brunel's 6-foot gauge is more than a few percent variation on the now standard 4'8.5" gauge.
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Old 2019-10-19, 07:11   #17
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Quote:
Originally Posted by xilman View Post
Brunel's 6-foot gauge is more than a few percent variation on the now standard 4'8.5" gauge.
What about the 7' gauge?
Quote:
Originally Posted by wikipedia
The Liverpool and Manchester was quickly followed by other trunk railways, with the Grand Junction Railway and the London and Birmingham Railway forming a huge critical mass of standard gauge. When Bristol promoters planned a line from London, they employed the innovative engineer Isambard Kingdom Brunel. He decided on a wider gauge, to give greater stability, and the Great Western Railway adopted a gauge of 7 ft (2,134 mm), later eased to 7 ft 1⁄4 in (2,140 mm). This became known as broad gauge. The Great Western Railway (GWR) was successful and was greatly expanded, directly and through friendly associated companies, widening the scope of broad gauge
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Old 2019-10-19, 08:15   #18
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Quote:
Originally Posted by Uncwilly View Post
What about the 7' gauge?
Thanks. I mis-remembered and forgot to check. My bad.
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Old 2019-10-22, 11:47   #19
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Quote:
Originally Posted by Uncwilly View Post
What about the 7' gauge?
It's not unusual for there to be outliers in technological development. There were electric cars and steam cars before gasoline established dominance a hundred years ago; rear and mid engine placement, tillers and other control approaches for steering, etc. The broadest gauges, if the story about rut pitch is accurate, may have been wide enough to make the pitch irrelevant, providing the paths were cleared widely enough. Tunnels could be an issue, and perhaps side clearance through forests and brush.
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Old 2019-10-22, 14:48   #20
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Ha, in 20 years of Thailand we wondered hundreds of times how close together the rails are here, and we are always afraid that their trains will capsize, at least five trains per day... We are still amazed of the fact this didn't happen yet...

Last fiddled with by LaurV on 2019-10-22 at 14:48
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Old 2019-10-22, 19:55   #21
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Quote:
Originally Posted by LaurV View Post
Ha, in 20 years of Thailand we wondered hundreds of times how close together the rails are here, and we are always afraid that their trains will capsize, at least five trains per day... We are still amazed of the fact this didn't happen yet...
Much depends on the center of gravity - a typical train car has most of its bulk up high, but the passenger compartment is mostly air, whereas the chassis and wheels are heavy steel. Of course passengers shift the Cg upward, especially in many 3rd-world-style countries where roof-riding is common when the cars get full. Passengers in regular seats, OTOH, are fairly close to the track, so don't shift the Cg upward very much. Studying this would make for a great science project for a school-aged kid in a train-heavy country.
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Old 2019-10-23, 02:57   #22
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Well, we know the physics. What I was describing was the "psychological" effect of crossing the railroad from time to time, like few times each year. Coming from an European country who was one of the first in the world to have train transportation on large scale, where few million people commute by trains daily, where everything moves by trains, where cars were not so common, because not everybody could have cars under the communism, you know..., the train was the main way to go everywhere, even in the most hidden corners of the map. Historically, they were used to transport coal, oil, and iron for almost 200 years, and in modern times the communists had the ambition to electrify every railroad. We still have some of the strongest and most elaborated electric locomotion engines in the world. Then I ended up in Thailand where the train transportation is totally non-existent, railroads are middle-age level, there is only one single rail from north to south, I mean a single track, the trains have to wait in stations for the trains in the opposite direction to pass, they have delays of 5 hours (like CM to Bkk in 16 hours instead of 11), and above all, the gauge is half of what we are used to be. My toy train in my kitchen which goes around the table has larger gauge**. Not to count the fact that if you ask anybody, and I mean ANYBODY about electric train, they will look to you like you were totally gone in the head...

Don't get me wrong, Thailand is quite advanced in many ways, including car/truck/bus transportation, and in some ways more advanced than western countries, and we love it, otherwise we won't be here for 20 years already, but when it comes to trains....

On the other hand, traveling by train here is fun, if you are not in hurry. They have quite nice and luxury interiors for the expensive class, and all seats (for all classes) can be pulled out and lifted up to be transformed in beds, so you can either seat, or sleep. And they are never crowded, because nobody travels by train, people travel by buses and private cars, and they usually commute by motorbikes. Well, mostly by "a motor under the ass", some people call them scooters.

---------
** I do not have a train in the kitchen, but that's the "feeling", and anyhow, it was funny to say it, hehe, in fact we are happy to have a kitchen, most houses don't have them, as people here eat outside, another thing that took us a long time to get used to.

Last fiddled with by LaurV on 2019-10-23 at 04:25
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