how did they do it?

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I heard a talk some months back, from one of  
the investigators of the Antikythera mechanism.  
Really fascinating.  Discovered over 100 years ago,  
it's just recently that they finally reverse engineered  
it, completely.  Or so the speaker claimed.

Apparently it was a long development, lasting almost  
a century, ~ 200 B.C.  There's a suspicion that  
Archimedes had a hand in, but no smoking gun.

It's an astronomical calendar, an astonishing  
achievement.  It could predict solar and lunar  
eclipses decades ahead!

An interesting point:  we have no user manual which  
specifies the device as a celestial calendar.  But  
the fact is, it makes an amazingly good calendar!  
Hence, Sherlock, it must be such a device.

In other words, if an unknown object serves a particular  
function, one may assume it was designed to that purpose,  
and a designer behind it.  With obvious implications for the creation/evolution debate -

Now the technical bit - it consists of a complex  
interplay of cogwheels; calculators.  I recall one  
had 53 teeth, another 127.  How the heck did they  
construct those?  How did they even DRAW them?

Today, with AutoCad, it's a piece of cake.  But in  
the days of Euclid?  So, the challenge:  armed with  
only your powerful 21st century brain and education,  
but B.C. era technology, how would you go about designing  
and cutting those wheels?

--
Rich



Re: how did they do it?
fredag den 10. august 2018 kl. 00.32.24 UTC+2 skrev RichD:
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a guy on youtube is making a replica mostly using tools and layout that  
would have available at the time

wheels laid out with dividers and made with files https://youtu.be/BIUAdINXZmQ


his channel is worth a look, he did a clock before



https://www.youtube.com/channel/UCworsKCR-Sx6R6-BnIjS2MA/videos


Re: how did they do it?
snipped-for-privacy@fonz.dk says...
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https://youtu.be/BIUAdINXZmQ

And of course: first make your file! ...

Mike.

Re: how did they do it?
fredag den 10. august 2018 kl. 08.44.32 UTC+2 skrev Mike Coon:
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https://youtu.be/SOw9WqMOHjA


Re: how did they do it?
On Thursday, August 9, 2018 at 6:47:59 PM UTC-4, Lasse Langwadt Christensen wrote:
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Nice, thanks.  
GH
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https://www.youtube.com/channel/UCworsKCR-Sx6R6-BnIjS2MA/videos



Re: how did they do it?
On Thursday, August 9, 2018 at 6:32:24 PM UTC-4, RichD wrote:
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The man who replicated it was on a Nova show about the Antikythera mechanism on PBS a few years ago. It explained how he determined it was 53 teeth and all...

Re: how did they do it?
On Friday, August 10, 2018 at 8:32:24 AM UTC+10, RichD wrote:
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lution debate -

https://en.wikipedia.org/wiki/Watchmaker_analogy

Once Darwin had proposed evolution by selective adaption, that argument was
 dead. The Antikythera mechanism isn't all that close to anything it might  
have "descended" from.
  
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Cast them? Filed them out of circular blanks?

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Euclid (323?283 BC) preceeds the Antikythera mechanism by about a c
entury.
  
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Carefully. A 53 tooth wheel would be a bit of a challenge, but Archimedes h
ad worked out an algorithm for calculating pi in 250BC, so it would be poss
ible to work out how long each of the 53 segments around the rim of the whe
el would have to be. Messy arithmetic, but even using 22/7 as an approximat
ion for pi would get you quite close enough.

--  
Bill Sloman, Sydney

Re: how did they do it?
On 10/08/18 02:25, snipped-for-privacy@ieee.org wrote:
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If you are careful about your choice of units, you can get very
accurate.  Draw your circle 135 units, and your 53 teeth will be 8.002
units around the circumference.

Re: how did they do it?
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I've a divider for a lathe. It uses holes in a regular pattern of e.g.
13, allowing for a 13 teeth wheel. However, there is a 40 to 1 ratio,
i.e. you could also do 13.40 or 13.2 teeth, selecting the number of
turns plus the right hole.
If you wanted 17 teeth you could select the right holes and the 17
teeth wheel wouldn't look half bad. Now if you use that create a
wheel with 17 holes and use that in the divider
the deviation would be cut by a factor 40. And you could do that again.

In a similar vain, you could estimated the distance for 53 holes.
Then you could file an oversized wheel, and then you could correct
the filings while going down to size, using a small fixture.
Doing some handywork didn't scare the ancient off, the acropolis
stones where fitting up to mm's by hand.

[The first lathe didn't have screws that are created on a lathe,
they had to be forged. Crude screws in a lathe allow to create
much better screws in a next generation. ]

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--  
Albert van der Horst, UTRECHT,THE NETHERLANDS
Economic growth -- being exponential -- ultimately falters.
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Re: how did they do it?
On Sun, 23 Dec 2018 19:10:38 +0100, Albert van der Horst wrote:

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An interesting observation. I always thought it worked the other way  
round.



--  
This message may be freely reproduced without limit or charge only via  
the Usenet protocol. Reproduction in whole or part through other  
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Re: how did they do it?
On Sunday, December 23, 2018 at 1:43:31 PM UTC-8, Cursitor Doom wrote:
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Filing was a normal procedure to make a screw to a measurement standard,
and a sliding 'nut' with a cutter can be made to cut a regular thread
(though not to a precise standard pitch).

So, the staircase to better precision DOES work by amplifying the virtue in  
subsequent generations: there are some odd economies involved, though.
Like, making a six-foot-long threaded gizmo to get a two-foot-long precision
section.  Part of the process was  written up in an old book, _Measuring the Universe_
that described apparatus-making about a century ago...that amusing item was in Granddad's
bookcase.

Re: how did they do it?

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files?  Internal cutting edges on a nut?  Back then?  You're not  
thinking this through.

Re: how did they do it?
On Monday, December 24, 2018 at 12:38:16 PM UTC+11, snipped-for-privacy@decadence.org wrote:
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Reporting on historical facts doesn't involve thinking things through.

<https://en.wikipedia.org/wiki/Jacques_de_Vaucanson

<https://en.wikipedia.org/wiki/Lathe

<https://en.wikipedia.org/wiki/Screw-cutting_lathe

The last item mentions hand-filed screw threads. Vaucanson is known to have worked out ways of making imperfect lead screws more nearly perfect.

--  
Bill Sloman, Sydney


Re: how did they do it?
snipped-for-privacy@ieee.org wrote in

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Yes...  it was AFTER the lathe.


  Before the lathe were there 'files'?

Yes, I know a file is not made on a lathe.

I was likely machining things long before you even knew what machining  
was.

Re: how did they do it?
On Monday, December 24, 2018 at 1:45:02 PM UTC+11, snipped-for-privacy@decadence.org wrote:
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There were lots of different lathes. Vaucanson is credited with inventing one of them.  

"In 1760 he invented the first industrial metal cutting slide rest lathe."

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Of course there were.
  
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This doesn't seem to have give you any grasp of the history of the development of the lathe.

https://en.wikipedia.org/wiki/Recapitulation_theory

is now generally accepted to be false, so this conclusion wouldn't be surprising even if the original proposition hadn't come from somebody frequently known as AlwaysWrong.

--  
Bill Sloman, Sydney


Re: how did they do it?
On Sunday, December 23, 2018 at 5:38:16 PM UTC-8, DecadentLinux...@decadenc
e.org wrote:
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There's an illustration of such a 'nut' here:

/Screw>

Re: how did they do it?
On Thursday, August 9, 2018 at 3:32:24 PM UTC-7, RichD wrote:
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Compass and straightedge, classically.   If you can get
a flat surface to mark on (stretched parchment?) and
inscribe a circle, you can subdivide it.  Powers of two are easy,
so you could use a binary fraction rendition of 1/53, 2/53, etc.
to get to any degree of accuracy you want.

That's why 'trisecting the angle' is an old well-studied problem.

Lens design used large sheets of vellum, H6 (very hard) sharp pencils,
and ratio-of-sines graphic calculation, up 'til the 1970s.
And a gizmo called a 'polar planimeter' integrated areas,
and an exceptionally clever device existed to do harmonic analysis
(for tide calculations, largely); it computed a Fourier transform,
mechanically.

I'm more impressed with the ability to produce flat bronze stock; someone
with a hammer is no match for centerless-ground rollers.

Re: how did they do it?
On 10/08/2018 01:34, whit3rd wrote:

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They probably did that by old mirror grinding techniques to get the  
final truly flat material by working three pieces against each other the  
same way optical flats and snooker tables are still made today. On the  
plus side they wouldn't need to polish it as carefully as for a mirror.

As Bill said they knew pi well enough to compute the right length for a  
known diameter of wheel and would doubtless have made a jig to allow  
precise construction of the gear wheels.

They could also have done it by successive approximation given enough  
time and patience. Prime numbers of teeth are more tedious to do.

53 & 127 are both inaccessible to the Neusis construction known to the  
ancient Greeks so they would have had to do a bit of a fiddle.

https://en.wikipedia.org/wiki/Neusis_construction

Engineers of the day would have been more likely to use this sort of  
method to get practical results for N-gons - straight edge and compasses  
geometrical purism came a bit later.

--  
Regards,
Martin Brown

Re: how did they do it?
On Thu, 09 Aug 2018 17:34:32 -0700, whit3rd wrote:

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Loads of really ingenious methods are outlined in this book:

https://tinyurl.com/yc4sr2dl

You can make a *perfectly* flat surface (terribly important to have one  
of these in every serious engineering shop) by placing two slabs of  
granite on top of one another, separated only by grinding paste and  
agitating one against the other. Eventually they rub off each other's  
imperfections and you get two perfect surfaces for reference purposes  
from which you can then make other highly accurate tools and so on.  
Clever stuff!



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Re: how did they do it?
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Three.  Two will give equal positive and negative spherical sections (or  
paraboloids if you grind them right).  Only in the case when three faces are  
ground against each other, will that spherical section have zero curvature,  
a plane.

Tim

--  
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
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