G'day Chris here and welcome back to Clickspring there are many carefully made components within
the Antikythera mechanism the fastening pins for example need to be well formed to fit
snugly within their respective holes it's the sort of work that's most conveniently
done by hand on something like a filing block quite precise results are possible
with this simple approach using a file a notch and some wood and maybe some abrasive
stones the nature of the pins suits this freehand approach some variability in the
form is not only tolerable but occasionally it might even be beneficial to the end
result for some of the other components the requirements are stricter the mechanisms
complex gear train is completely intolerant of friction it's many arbors and pivots requiring
true cylindrical shapes to avoid binding the hand filed approach is mostly not suitable so
if not essential then at the very least a lathe of some sort would certainly have been a useful
part of the tool suite used to construct the mechanism we have clear reference to
lathe technology in the surviving literature from the period as well as a depiction of an obvious
progenitor we also have a lot of turning debris and artifacts but to date little remains of the
actual tools themselves there's a distinct gap in our practical knowledge of the lathe
technology used to construct the Antikythera mechanism so what was the likely form of that
lathe and what was it like to use it to create functioning components for the device in one of
the previous videos in this series describing a scorper and trammel I showed that the large
circular shapes found in the mechanism can be cut with precision using a simple tool
consistent with the metal working technology of the time so this leaves only the formation of the
small round components like the arbors shafts and bearings to be explained they're generally fairly
short and thin so we're already talking about a relatively small tool the size of the parts
also means that we can rule out any requirement for a pole driven mechanism a hand operated bow
will provide more than enough driving power the tool must be able to produce well-finished bearing
surfaces to close tolerances and the operator needs to be able to get physically close to
the work to be able to see it well enough to assess progress all of which suggests a tool
on the scale of something like this in my case I've let the prongs into a piece of wood that
I can then hold in this work holding device but they could just as easily be let directly into
the bench or put in some sort of standalone frame the key feature is the opposing points
between which the work is caused to rotate for the bow I've I've used a thin springy length of wood
I've formed a notch at each end in preparation for stringing the bow with a natural gut line
the tool now has a reasonably ergonomic form it's at a convenient eye level for
work from a standing position and once the bow is wound around
the workpiece a full draw will end at a normal relaxed arm extension
a cutting tool rest need be nothing more than a piece of wood or even strips of leather underneath
or adjacent to the work axis I found it helpful to use a few drops of wax it holds things in place
and still allows the rest to be pushed into just the right position whenever needed the cutting
tools are another example of the carburized iron cutting tools that I have been using at various
points in the construction of the mechanism each lathe cutter has been forged and then carburized
using the leather-charcoal-and-salt carbon pack described in a previous video once tempered the
cutting edges are brought up and then continuously maintained as the work progresses using abrasive
stones okay so let's have a look at what the tool can do with a piece of wood I'm
using ebony as a test piece a wood recorded as being used in the furniture construction
of the time a light trim with a chisel gives a slightly better starting point for the first
lathe cuts and two light punch marks are put in place to catch the centers a key feature of the
lathe is that the two prongs are lightly sprung when a workpiece is loaded in-between providing
the closing force that holds it in place it's convenient to load and then unload the lathe
a small twist and the work pops out reverse the move and it's back in place again if the
workpiece is a little too long or short for the prong spacing the next hole along can be used and
at any position the prongs can be slightly bent in or out to modify the closing force
the first cuts are interrupted and so a little course to begin with but the
great attribute of the lathe is its ability to bootstrap itself into a
more capable state after a light notching cut at one end the work can be repeatedly
flipped end for end gradually improving the surface gripped by the bow-line
the line grip is improved further still by applying a small amount of rosin to
the line a material that I've used in a previous video showing its potential
role at the time as a soft solder flux okay so with a smooth direct drive and
a reliable grip from the line some real work can begin in this case I'm going for
a general reduction of the workpiece and a thin lightly tapered arbor on one end
the work is now close to being a suitable diameter upon which to mount a metal work
piece using a friction fit generally speaking raw metal stock is likely to have been cast
forged and then filed into a basic starting form from there additional starting features
like for example an internal bore can be completed using the pump drill and hand files as required
once close to size both the arbor and workpiece
can be carefully adjusted and then pressed together for more turning
so fairly quickly we end up with another another potential upgrade of the tool the bearing parts
are filed as required for a snug fit as well as a suitable position of the pulley relative
to the pivot point then once pressed together the pulley is captured making sure to leave a little
end-shake for free movement
so now in addition to the direct drive method shown previously we now also have an
indirect alternative that can be used depending on the workpiece requirements in
each case catching the driving force however best suits the occasion while still making use of the
core features of the bow lathe: two pivots a rotational force a tool rest and a cutter
an occasional spot of olive oil on the bearing points helps to keep things moving and the
cutting progresses in a way that would be familiar to Modern clock and watchmakers
because this is basically a crude version of a watchmaker's turns the lathe technology used to
build the first mechanical clocks and watches and a precursor of much of what was to come
during the time of the mechanism's construction this early version of
machine technology must surely have been quite something to witness our understanding
today is that while its origins are not precisely known it's likely that the art
of constructing this type of mechanism was practiced on the island of Rhodes
a naval and trading power in its own right and a key stopping point for merchants in the Eastern
Mediterranean Rhodes interacted deeply with the Greeks Romans Egyptians and other powers of the
region yet ultimately Rhodes would become established much like Alexandria in Egypt
as a center of Science and Technology where those with the means such as Roman nobility
would attend its schools and personal lectures given by well-regarded scholars
among those Scholars were some of the most famous names of ancient astronomy mathematics
engineering and philosophy individuals like Geminus the author of an influential student
text on astronomy the "Introduction to the Phenomena" Hipparchus whose astronomical
theories appear to underpin several features designed into the mechanism and Posidonius the
stoic philosopher in polymath who was said by Cicero to have constructed a similar type of
device the passing references by Cicero and others to devices and technology that sound
similar to the mechanism recovered off the coast of Antikythera lack the detail to tell
us much more than that they existed so today we're left to wonder about the specifics of
where by who and precisely how this art form was practiced the mechanism itself providing
just enough detail to keep us thinking asking questions and Imagining the possible answers
The bow lathe is a straightforward tool to make using the tools and materials
of the time and it's able to produce all of the turned complexity exhibited in the
wreckage of the Antikythera mechanism it's also one of the simplest ways to implement
an intrinsic property of our world where a body spun between two points can have
its profile shaped true to its axis and so be transformed into something meaningful
from this key principle everything else follows
thanks for watching I'll see you later