Wind back to 2300 BC

[DeadLatheOwner]

SO i was having a debate with friends over a curry.

The earliest known reference to gears was circa A.D. 50 by Hero of Alexandria, but if yoiu think the Antikythera mechanism is genuine then someone was making brass gears around 2300 BC

Its chicken and egg tho - how do you make the first gear, if you possess no machine with gears in ? How could it be done ? Do you need gears to make gears ?

 

[ausdier]

A couple of pictures of how to make simple gears without any real precise machines.

Da Vinci was using them for his machines like his driving wheels of his tank.

Hope this is a bit of an answer.

 

[mklotz]

I think you're really asking how the angular dividing was done. After the dividing, the gear teeth can be filed by hand. I believe the Englishman who built a replica of the Antikythera mechanism did just that.

Obviously many divisions of the circle can be accomplished with nothing more than compass and straightedge. For other divisions, here's an extract from the text file that is included in my DPLATE archive...

Imagine you've turned yourself a top-hat shaped piece of steel. Now imagine
you've turned 14 circular disks. When you paste these disks on the brim of the
hat, touching (what I'll call) the 'crown' of the hat, they all just fit,
simultaneously touching the adjacent disks and the crown. Voila, a '14 hole'
dividing plate. All that's required is to make a suitable detent to locate
between adjacent disks and you've got a dividing plate. With such a
contrivance it would be easy to use it as a locator to drill a more
conventional dividing head plate.

If the diameter of the crown of the hat is known, it's only a bit of
elementary trigonometry to compute the required disk diameter for any number
of divisions. The attached .jpg file illustrates the arrangement and the math
that must be done. While straightforward, a small program makes things
easier. After all, the program will never transpose a digit, forget a term,
take a cosine instead of a sine or make any of those other idiotic mistakes
we're all so prone to make. Moreover, you'll probably want to experiment a
bit to get a combination of crown diameter and disk diameter that fits your
available stock. That means solving the same equation several times. So much
easier with a program than a calculator.

 

[Rayanth]

i have been studying the antikythera mechanism quite a bit off and on over the past years. I've Asperger's and one of my thorough passions and infatuations is with gears. What a marvelous device, and so ancient! I've honestly focused more of my study of it on the gearing mechanisms than the history and how-to, but I do have an interest in making one on my own. (aside: the fixation on gears is what led me to engines. gears need to do *something*, and ostensibly need to be powered by something as well...)

I've come to a similar chicken or egg question on my own, many many years back, involving a much more rudimentary geometrical construct : the straight line.

Without any straight lines/edges, and only the most basic tools available... construct a straight line. How can you prove it's straight? (essentially, how do we know the first claimed straight lines were truly straight? how do we even know straight lines today are truly straight, if they were derived from that original?)

- Ryan

 

[Lakc]

Without any straight lines/edges, and only the most basic tools available... construct a straight line. How can you prove it's straight? (essentially, how do we know the first claimed straight lines were truly straight? how do we even know straight lines today are truly straight, if they were derived from that original?)

- Ryan

The same way machinists qualify flatness, you take three of them and compare them too each other.
Straight is rather easy I would think, any taught line should tell you that.

Bisecting angles and dividing circles are some of the earliest math. What took so long I think, was the brutal way conquerors used to eradicate technology of the vanquished, and society had to evolve to allow the masses suitable time to study those arts, instead of hunting and tending to the fields.

 

[Rayanth]

Ah, but a taught line is still influenced by gravity and thus not truly straight. (And materials to make such a line not refined enough to be so reliable)

I propose the question more as an abstract quandary, I suppose. There is so much that history has lost and we now simply take for granted. Or perhaps such things were gifts to us from an alien race, as proposed in the discovery channel series "ancient aliens"? It could explain much.

Ignore these ramblings of a lunatic

- Ryan

 

[DeadLatheOwner]

The only true straight line would be a beam of light. SO, you start with a pinhole in animal skin shone obliquely acros a flat surface and marked up ?

 

[mklotz]

A non-vertical taut line or light beam will be bent by gravity, though not enough to matter for much of anything you're likely to build. A vertical taut line (plumb bob line) would have been a useful reference for the ancients.

However, understand that 'the straight line" is, like so many other geometric entities, only an abstraction adopted to separate the pure mathematics of geometry from the rough, gritty substance of the real world. You don't need an actual straight line to prove geometric theorems, you only need the idea of one. There are no perfect circles in the real world either yet the mathematics we derive from imagining one are still very useful.

 

[DeadLatheOwner]

There are no perfect circles in the real world either yet the mathematics we derive from imagining one are still very useful.

AH, now we coudl take issue with that!!

A star is a gravitationally bound ball of plasma in a zero gravity field, and because gravity is homogenous and isotropic, it forms a perfect sphere to an astonishing accuracy. In fact, any gravitationally bound fluid body in a zero gravity field does the same - the event horizon of a black hole is spherical to within a Planck Length (10^-43 cm), its has to be, it has no choice because gravity at the event horizon is infinite.

In the real world, a pebble dropped into a pond produces circular ripples that have no choice but to be perfectly circular. Its only in the natural world that we find perfection in shapes.

All the mathematical shapes can be drawn with light:

SO, I think the first gears must have been made as suggested by dividing a circle with a compass into a peg toothed crown gear. The straight edge you can make by working two almost flat edges against each other, and the circle you can make with a string an marker. Axles and shafts you turn out of wood on a treadle lathe. The biggest hurdle in my view is the leap from wood to metal and the racheting up of the accuracy required. You can carve peg teeth on a wooden crown with a knife, but making a pinion from brass requires much better accuracy.

So the secondary question really is who made the first metal working lathe and how?

 

[kvom]

I think that's 2300 years ago or 300 BC, not 2300 BC. The Antikythera has been dated to about 100 BC.

I read an interesting article about why it took humans so long to develop the wheel. Seems that while the wheel itself is a simple concept, it was developing axles that were the real problem. Making a long, straight rod and suitable bearings were the roadblocks.

 

[jerrybilt]

My two cents worth about straight lines:

A straight line is the shortest distance between two points.

A beam of light will take the shortest distance between two points.

If gravity bends the space through which the light is traveling then the light will follow a curved path and this will " look like" a "straight" line as it will be the shortest distance between two points.

Jerry.

 

[Maryak]

If gravity bends the space through which the light is traveling then the light will follow a curved path and this will " look like" a "straight" line as it will be the shortest distance between two points.

Jerry.

Circles great and small ;D

Best Regards
Bob

 

[DeadLatheOwner]

My two cents worth about straight lines:

A straight line is the shortest distance between two points.

A beam of light will take the shortest distance between two points.

If gravity bends the space through which the light is traveling then the light will follow a curved path and this will " look like" a "straight" line as it will be the shortest distance between two points.

Jerry.

Ah yes but..........that's not necessarily always true

We live in a 5 dimensional Euclidean phase space (i'll go into why its 5 and not 4 or 3 as the unwashed masses imagine in a minute), and the laws of geometry work as they do because in this universe, parallel lines do not converge and the angles in a right angled triangle add up to 180 degree. This is because the universe is flat. There may be other universes in the same 5 dimensional phase space that are not flat, and therefore there may be other geometries that are true. The problem is, they will make the same argument about us. So all lines look like they are straight, in any universe, but you can only tell the difference by observing from the next dimension up.

If you cant get you're head round it, let me use an allegory. You know that a rubiks cube has three dimensions up/down + left/right + nearer/further. However, you cannot OBSERVE this in a 3 dimensional space, because it contains no time. The 4th dimension, as is usually explained, is 'time'. This is not really true, in the same way one of the other dimensions is 'left'. You cannot have 'left' without 'right', and thus 'time' isnt a dimension, its a direction. There must also be an opposite' - 'antitime' or if you like 'reverse time'. So time is a direction, the name of the dimension its in is, lets call it, "Duration"

The only way to observe an object in 3 spatial dimensions is to include the 4th dimension of 'duration'. That allows you to perceive it, since you can see it moving and recognise. what it is. Thus , to tell the difference between straight lines in 4 dimensional phase spaces, you have to observe them in 5 dimensions. This must be true for at least 5 dimensions as far as we are concerned.

sorry, dangerous subject to get me on.

How did we build the first metal lathe then?

 

[arnoldb]

How did we build the first metal lathe then?

Most likely with castings or forgings and manual hand tool work. Machines are a convenience of the Industrial Revolution.

Our ancestors weren't quite as lazy as we are today, and often-time were prepared to labour for many hours with very basic hand tools to build a machine. Spade drills to drill holes were forged up and sharpened on a stone. Files were made by hammering the teeth in them with chisels. Chisels were made up from red-hot bits of steel hammered into shape and then sharpening them on stones. They didn't throw a tantrum and have to close down shop for the day when the battery in their cordless screwdriver went flat

While it seems incomprehensible nowadays, wooden bodied lathes could easily be used to machine metal. No calculations about RPMs and SFMs and stuff like we tend to do while machining, but rather extended hours of manual slog to remove just a small amount of metal.
The origin of the lathe is lost in the mists of time - nobody knows who invented it. I have a hunch it evolved in different civilizations in parallel, but then I'm not an archeologist or historian, so my hunch is just that.

Regards, Arnold

 

[arnoldb]

DeadLatheOwner, unfortunately I had to remove the images you posted after my previous post - while they were fun to look at, they are copyrighted, and cannot be used for public display here.

Regards, Arnold

 

[dalem9]

I will bet that you all beleive that a cricle can be made with a square . But it can.

 

[DeadLatheOwner]

In universes with non euclidean geometry it already is. 8)

 

[Robsmith]

I think that's 2300 years ago or 300 BC, not 2300 BC. The Antikythera has been dated to about 100 BC.

I read an interesting article about why it took humans so long to develop the wheel. Seems that while the wheel itself is a simple concept, it was developing axles that were the real problem. Making a long, straight rod and suitable bearings were the roadblocks.

Rubbish ! Look at Fred Flintstones car...his bearings didn't even have keepers. They still can't do that today !;D

 

[enfieldbullet]

i would actually like to contribute something here. i have some background on generating geometries and history of machine tools so i think it would be of some help to the question of how do you make the first straight edge or the first lathe.

making a straight line or plane is a rather simple process. it consists of using reversal techniques and hand work. even today, the most precise machines are still hand-made/fitted, as it is impossible to a machine to make another of a higher degree of precision(this is only achievable through human work).

the process itself is fairly long to explain in one post, i can elaborate if wanted, but basically it consists of reversing similar geometries and comparing them. you can create a true flat plane or a true straight edge by using 3 pieces (this has to do with the 3 dimensions).

so we could say the first straight edge was never created, because by the time it was there were already two others *grin*

the lathe is also a fairly straight forward machine to build in concepts. that doesn't mean they're easy to figure or to make. it would be possible to do completely by hand from the casting, just taking lots of time (which is why those machines were built in the first place, to save time).

the two main processes( or tools) that mankind developed which made this possible is lapping and scraping(as in scraper).

the first lathes capable of fine metalwork probably looked a lot like watchmaker's turns( i love those).

as said making gears is all about dividing the circle. that can be done with a divider(compass).

anyone interested in this should read Connelly's machine tools reconditioning(which talks a lot about techniques that can be used to build machines) and Moore's fundamentals of mechanical accuracy(which talks about making flat planes and why an inch measures exactly one inch, etc)

sorry if this thread is too old to post. hope this information is useful.

 

[goldstar31]

I think that 2300BC is actually too recent! Somewhere Man lost his way in what we laughingly call the Dark Ages.
For my two pennorth, I would not dare to disagree with what has been written but to say that I did read up Professor Alexander Thom and the his deliberations on the Megalithic Yard and Knight and Lomas on the Planet Venus.

It's heady stuff and if the Doubting Thomas's of this World think that it has nothing to do with 'Machining' they are way out. With tongue in cheek, the pioneers would never have found California-- unless they did exactly what their forebears did- Point your waggon.

Oddly, I was brought up in the Bronze Age, I spent many a night with a skeleton and a pair of graves in my old mentor's garden as part of his little golf course. We know a little more now of these people from a far off age but not a fat lot. Across to the North of where I live are the Cup and Ring markings on the Simonside hillside. We have the scantiest of ideas- but no more. Tomorrow, I should be flying to where there is 'an upturned boat' made of stone in which people were buried. Next to my little home there are Taulas and Talyots- a bit like Stonehenge. Cleverer people than I have postulated-- whatever postulated means.

The only firm conclusion is that whoever they were- they didn't have the internet.