G'day Chris here, and welcome back to Clickspring. Its a tool that we reach for in the shop,
without a second thought. Yet the common hand file is so old, that its
origins are essentially unknown. And it was almost certainly one of the key
tools used to make the Antikythera mechanism. For filing squares and perimeters, and most
importantly, for forming those incredible teeth. So in this video I'm going to hand cut a set
of precision files suitable for constructing the mechanism, using the materials and methods as close as
I can get them to those of the period. The Greek civilisation was well into the Iron
Age at the time of the devices creation. But the question of steel availability is
not easily answered. Certainly there was a form of crucible steel
known as Wootz, from the region we now call India. But there was also the technique known as
case hardening, which essentially converts the surface of
an iron object into steel. Tool artefacts recovered from the period suggests
that this second option is the most likely of the two. Now I don't have any true wrought iron, but I do have this low carbon mild steel,
which is fairly close. It has too little carbon to be quench hardened, and its soft enough to still be worked in
a similar way to ancient wrought iron. So for the purposes of this exercise, I think
it's a reasonable substitute. The first step is to take this raw stock,
and shape the basic file blanks. In recent history, this job was done on a
massive grinding wheel. And although it would of course have been
much slower and less convenient, similar hand powered abrasive tools are known
to have existed in antiquity. The surfaces of the blanks are now required
to be filed perfectly flat, or stripped. Traditionally the tool for this job is a stripping
frame. I've made this one from oak, and fastened
it onto a board with dowel pins, to keep it secure on the bench. Its a tool that operates a bit like a clockmakers
swing tool. No matter how much I roll the file on top
of the work, it rotates so that the file will still cut
reasonably flat. Ok, so with the file surfaces stripped, the
next step is to form the teeth. And I need to make a few more custom tools
to get this part of the job done. I've made a simple file cutting workstation,
based on the traditional approach, but scaled down to suit the size of my shop. The file cutting anvil is a piece of scrap
mild steel covered with a layer of tin, that will protect the file teeth during the
cutting process. A register on the other end seats securely
within this recess on a wooden base, and I made a pair of leather straps to hold the blank onto the anvil. The file cutting chisels were made from this
mild steel plate, again to simulate the wrought iron of the
day. The chisel profile was formed using the grinder
and belt sander, and then they were hardened using the traditional
case hardening process. Now ordinarily case hardening is used to harden
only the exterior of a part. But in this case I left the parts in the furnace
long enough to ensure that they could be essentially through
hardened. This allowed me to grind on a cutting edge
without being concerned about reaching a soft core. The chisels were then tempered, to leave a
pale straw color at the cutting edge. OK, so after all of that preparation, its
time to cut some file teeth. And they're formed in a remarkably simple
way. The file blank is secured on the anvil using
the straps, and I found that having a protractor resting
nearby was enough of a guide for the cut angle. The chisel is positioned on the workpiece,
and then tilted back slightly, to generate an appropriate rake angle for
the tooth. A sharp hit with a hammer and the first tooth
is formed. A small amount of oil lubricates the surface, so that the chisel will move freely with only
light fingertip pressure. And that first tooth now becomes the reference
for the next tooth. The chisel blade is slid up against it, and then the subsequent teeth are laid down
one after another. Each time, using the previous cut to locate
the next. There is of course a non uniformity to the
tooth spacing. But I think the most interesting thing to
see up close, is the side profile of the cutting teeth. One after another raised up above the surface, the geometry is exactly as you'd expect for
a cutting tool, with rake and clearance clearly present. The blanks have been prepared with the Antikythera
Mechanism in mind. The triangular blanks in particular have been
shaped to match the known tooth angles of the wheels. And I'll talk some more about that towards
the end of this video. Otherwise the cutting proceeded as you'd expect. Most of the other surfaces were cut with a
single cut pattern, but I did give some of the files a double
cut pattern to investigate if it would make much difference. And the wider chisel was used to span the
wider blanks. The files were then hardened using the same
case hardening process that I used for the chisels, and then tempered to pale straw. Now case hardening is a fascinating subject
all on its own. There's a lot going on at the surface of the
metal, that's worth investigating in more detail. I've separated the process out into its own
video, so be sure to check that one out next. OK so the moment of truth. Just how well does a shop made file really
cut? Well I'm not about to give up my commercially
made files any time soon. But they do work quite well. They're probably equivalent to a modern #2
cut file, and although the cutting action is not quite
as sweet as a new, modern file, its a reasonable balance between metal removal
and surface finish. They're durable, easy to handle, and certainly
perform well enough to have constructed the original mechanism. In fact, I suspect that custom triangular
files might be the key to understanding how the tooth profile was
originally formed. I'll talk more about this in a later video
, but the tooth root angles vary quite a bit across the device. From as low as 70 degrees to almost 90 degrees, with most sitting somewhere around 75 degrees. I've incorporated this tooth shape variation
into the way that I've modelled the teeth. Although I'd like to be clear that its not
quite as straight forward as this in the wreckage. There are many variations and inconsistencies. And the wreckage itself is in such poor condition that its impossible to be certain about much
of it. But nevertheless, it's definitely observable,
that in general, the smaller wheels have a wider root angle
than the larger wheels. I interpret this as a deliberate design choice, made by the maker to give the gearing better
clearance and a smoother engagement. And Its certainly possible that the range
of root angles found in the device, was formed by a single triangular file, that
was simply rolled on its axis to sculpt each tooth. The wreckage displays a fair degree of non
uniformity, that you'd expect for teeth hand cut in this
manner. But there's still quite a high degree of consistency
of the root angles around each given wheel. That suggests to me that the teeth were in
fact formed by simply plunging the file into the workpiece,
much like I've done here. And that the root angle variation observed
across the gearing, was in fact generated by a small selection
of files cut specifically to construct this mechanism. Ok, so to wrap this one up, Its still very
early days for this reconstruction. And I've still got a lot more research to
do into the tool technology behind this machine. But I think you'll agree that its worth it. To see the picture of the ancient workshop
that's starting to emerge. Of a single individual, or perhaps a small
team, working with simple, yet highly effective tools. Developing the workshop traditions, and refining the engineering practices that
would one day shape the modern world. Thanks for watching, I'll see you later. Now if you enjoyed this video, and you'd like
to help me make more, then consider becoming a Clickspring Patron. As a Patron of the channel, you get immediate
access to the patron series of videos. This includes the 5 videos from the Wedge
Style hand Vise build, and at present the first 4 videos of the BSC
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mechanism. And don't forget that as a Patron you also
get free access to the plans for the patron series projects, so you can
follow along and build it yourself if you wish. Now as an added patron reward, for a limited
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to find out more. Thanks again for watching, I'll catch you
on the next video.
The Antikythera mechanism is a spectacular piece, I've seen it up close and it just blew my mind!
Man. I'm just in awe of this dude.