[William P]

[Randall Moffett]

William,

Never said they did not. Only the massive use of slave labor limited many technologies.

RPM

[Craig Shackleton]

I'm going to go out on a bit of limb by trying to stretch my memory from something my old Roman history prof said years ago, so forgive me if the details are wrong. Even if I remember correctly, he may have not got it quite right.

Whichever Emperor decided to remove the head of the colossal statue of Nero and replace it with the head of the sun god was presented with plans for a crane that would allow the work to be done cheaper and faster by fewer workers. The Emperor's response was something like "Then what would I do with all of my slaves?" This story was intended to show us how the Roman institution of slavery impeded technological development. It seems to me that this applies particularly to state-funded ventures.

[Lafayette C Curtis]

[Johan Gemvik]

I’d like to think you could make solid rings with a lathe in roman age.
To me it isn’t so much a question of if it could be done or even if it ever was, but if it ever was the main way to produce them.
Sometimes we find they used strange and roundabout ways to make things historically, but usually it’s the reverse. When we try to imagine or recreate techniques we fall short of what they did back then with simple tools and lots of time to think about how to use them, because today we have little time and a lot of power tools to make up for not doing things in the most effective way in the little details of hand crafts.

So is lathe-cutting and effective method compared to punching rings from plate? Let’s make yet another comparison.

Work time per item produced?
When you get up to speed with punching from plate it takes about 10 seconds total for inner hole and outer hole to be punched creating a ring. Drop forging it afterward adds another 5 or so. 15 seconds per ring (not counting making strips of plate) equals 4 per minute. 30*4= 120 rings in half an hour, that’s 85 more, or approximately 358% more produced items per time unit than Greiners test.
In this regard the plate punching has a clear lead. However at this breakneck speed it would be exhausting work after a while (for the slaves). But even if we double the time per ring (more humane to those poor hard working slaves) and go at a slow steady pace it’s still considerably faster than cutting rings on a lathe.
So if that part is faster it’s the rest of the process that determines which is the more time effective method.
So then, how long does it take to hammer out a strip of plate from a iron bar? After all, it doesn’t need to be a wide spread sheet like those we buy today, just a strip with the right thickness. My guess is the speed a skilled blacksmith can make a fairly even strip from the same rod used for lathe cutting is about equal to setup and drilling a center hole in the same rod. A couple of minutes.
To know for sure someone would have to have both a historical lathe capable of drilling iron (probably not the foot pedal & rope kind we use for wood at demos but a more massive stationary water wheel powered one with gears) and a blacksmith with a forge heating and hammering out a strip.
Am I right in my impression that Greiner’s used a fairly modern but old hand-cranked lathe with a typical massively powerful electrical motor? It can give some idea how this could work certainly, but it won’t tell the whole story until he’s constructed at least a plausible roman style lathe that can do the same work. Did he test time for forging out a strip for punching?

This all also overlooks the fact that the workshop owner can just get more cheap slaves.
I suspect an advanced water driven high power lathe would have been quite expensive and plate punch tools though hardly cheap as hand tools go would cost a lot less, even in large numbers. There’d probably be room to buy several sets of them and some cheap slaves to work them before matching the lathe cost. So probably not one slave and a set of tools vs one lathe setup with one skilled worker to run it, but one lathe vs a villa full of slaves with punches. Or as has been stated already, a barrack of cheap soldiers under contract.

I’d like to see a scientific cost comparison for the lathe capable of doing the work described and a workshop with a number of slaves and simple punch blocks and punches.


The drill for the iron rod & lathe?
First off, does the paper specify the drill used to hollow out the iron rod? Is it a modern twist drill? Because according to Wikipedia (which is I know, not the most reliable but can be a fun start for research) the twist drill bit was invented by Steven A. Morse of East Bridgewater, Massachusetts in 1861. Though it was likely based on much older design, after all Archimedes invented the basic shape way back at some point during his lifetime from 287– 212 BC. You probably don't need the screw design to drill metal, mostly it transports debris from the cutting zone, but it would make drilling deep into materials easier and with fewer stops to remove debris like you need to do with spoon drills and such.

So exactly what would the tools used in roman times have looked like, most of all what did the drill bit look like that could drill a rod into an iron pipe and where can I see finds of these?
I’d like to see one since I do a lot of historical metal work and I always feel awkward using modern day twist drills to make rivet holes. Or holes in rods. I was under the impression you’d punch these historically since you didn’t have modern style twist drills like that available. I’d be very, very happy to be wrong about that so I can use them for helmet making and such with a good conscience.

The punch burrs?
I get sharp edges and sometimes some very minor burrs from punching solid rings. These are so minor they disappear if I tap the rings lightly with a hammer. Not to mention that no burrs will remain after drop forging of solid rings.
Drop forging can result in perfect square rings with slightly blunted edges, I imagine that’s what he’s seeing in the finds.
My first attempt at making a drop forge tool makes rings just like that, then the second I made was more rounded to emulate the much later age Gjermundbu better.

The centering issue?
Centering the second punch is as simple as adding a step-in diameter at the end. Centering gets even easier if you round the tip corners a bit. This results in a perfect centered ring every time.



The bottom tool in the photo shows the guiding tip I refer to. This is a plausible purely practical based tool I made, i's not based on any historical find

Let me just make a note here that some of the rings on the Gjermundbu are not perfectly centered, so for me this was “cheating”, or not fully replicating the Viking age process for that maille. But if it’s centering you want for roman mailles this is a good way to get that result.

[Sean Manning]

Johan, Greiner just says that his lathe was made in 1960 and turned at 300 revolutions per minute (U/Min). He seems to have used a modern twist bit on the drill. The Oxford Handbook of Engineering and Technology in the Classical World says that most ancient drillbits were a diamond-shaped blade set in a wooden shaft. I suspect that if Greiner were here he would say that he just did a simple experiment to show that his method could have worked.

I agree that an experiment which started with iron ore and ended up with patches of mail made by several different methods would be best. But it would probably take a few years and cost a lot of money by humanities standards.

[Jamie Hall]

I had to join the forum just to respond to this discussion, which I've found very interesting. My background is a little different to what you're talking about here, as I'm a jeweller, but I work with the Staffordshire Hoard, specifically with wire manufacturing, and the production of chain is something I've been pondering for a while.

Basically, my work deals with alternative ways of making round wire; I've noticed during the discussion that "making wire" is used synonymously with "wire drawing", but there are various other ways of making, or faking, round wire, and these have some relevance to the discussion. I'm aware, obviously, that the Anglo-Saxons are outside the period! But the techniques I deal with are relevant throughout the classical period, and up to about 1000AD.

Evidence for the use of draw plates is very thin on the ground; that's not to say that there were no draw plates, but they may have been a niche high-tech tool, rather than a ubiquitous means of making wire. It's a bit of a nebulous thing to say, but the same applies to any technique; if something exists in one archaeological example, it doesn't mean that everyone used it.

There are a couple of wire-making methods that might be relevant here. The first is block-twisting, which is used to turn thin strips of metal into round wire by twisting them and rolling between two blocks to compact the metal, and if done well enough, the seams are almost invisible to the naked eye; this is going to be harder to achieve in ferrous metal than in non-ferrous, but the technological requirements are neglible in comparison to making an appropriate draw plate, regardless of the metal used to make the wire. I suspect that most ferrous chain is too corroded to easily examine, but I wouldn't be surprised to see signs of block-twisting. However, when you look at the chain that Johan posted an image of, it looks very much like round wire - I'd love to see a cross-section of it, or have a look under the microscope, but I must admit that it's a convincing argument for the use of drawplates.

But I do wonder how much mail is actually made from round wire - rectangular-ish seems to be a common cross section, and that's unlikely to be made using a draw plate. Punching, as a metalsmith, seems to be a logical way of creating such links, but it would be unscientific of me to ignore the lathe/tube concept, so lets have a look at that (see, I was being on-topic all along).

Even without a fully function drawplate, it's possible to make a type of wire/tube called "strip-drawn". Simply put, this is a strip of metal that is pulled through holes in a draw plate until the strip begins to curl into a seamed tube, which can be soldered. This is an ancient method that was actually used by jewellers until the advent of extruded tube in the modern age. The drawplate itself isn't exposed to high mechanical stress, and so it doesn't need the tiny steps (0.05mm on many modern plates, but at least 0.2 is required); it is also possible to make the plate from a much softer material - eg. fine silver can be strip-drawn in a wooden plate; that can't be extrapolated to ferrous metal, but ceramics or even bronze might do the job - we're not talking about stretching the strip, just bending along it's short axis. Regardless of what you think about the drawplate proper, artisans would have had access to these "proto-drawplates" long before the proper ones were available.

So, if I was making tube, I would do it using the strip-drawn method. In fact, I'm itching for a chance to try it on such a large scale. But the point is that there are ways of making tube that are quite simple and effective. What I wouldn't do is use a lathe. Let's say that we have a lathe - it won't be running very fast, and its accuracy is likely to be low. Because of this, and because of the lack of modern twist drill bits, we're talking about brute-force grinding a bore down an 8mm rod at only a few RPM, and *then* cutting into that tube from the side. Physics says that the cutting tools need to be harder than the target material, so we know that the lengths of rod would have to be very short, or the force of the cutting tools would deform them! I say this because a long length of soft iron is going to bend easily, in the same way that a foot of railroad track is very rigid, but the 90 metre lengths they install on the London Underground wobble like crazy until they bolt them down. Given a tube of infinite length, it might be efficient to cut off rings using a chisel, but in reality, the artisan would be constantly boring short lengths, cutting them, and then swapping out for another short length; without proper chucks, accurately centering the tube/rod would take some time, during which the chap with the punch has probably produced several dozen links!

I'm really keen to read the german paper, if it's ever made available in English, and I'd love to see some analytical work that backed up the idea of boring and cutting tube. I'm also going to have to explore the work done on rolled sheet, because that really is revolutionary if it's the case - there isn't a suggestion of any sort of mill until the 1500's, when the first slitting mills appear, so use by the Romans would bring it forward by over 1000 years! As someone who rolls out sheet and wire every day, and has made them without modern equipment too, this is very exciting stuff.

Anyway, I hope this is a useful perspective on the subject, and I look forward to hearing what else people have to say on the subject.

[Dan Howard]

Thanks for joining in Jamie. Erik always said that mail making was more like jewellery than armoury. I know that other methods were used to make iron wire but in the Roman context, the dimensional consistency of a lot of samples strongly suggest that a draw plate was used for at least part of the wire-making process. Analysis of slag inclusions suggest that it was drawn too, and there are at least two Roman draw plates have been found. Thanks for your insights regarding tube making.

[Matthew Amt]

Yes, Thank you, Jamie! One thing I would emphasize about "strip-drawn" tubing is that it would have a visible seam, soldered at best, unless there is a reasonable way to forge-weld it. I'd be skeptical about soldering, since no one has noticed soldered rings on Roman mail before. (Plus the obvious question, why have soldered rings alternating with riveted?)

Valete,

Matthew

[William P]

one issue i keep hearing on this forum about pre modern iron is that of slag intrusions creating weak points, it was mentioned earlier in the thread, slag might cause the drawn wire to snap at a frustratingly bad time.

Jamie im curious if you have done any testing/ research on whether this method of rolling a strip between 2 blocks to make wire, or any of the other wire making methods, will increase or decease the likelihood of these slag intrusions causing the wire to break.

Also have you looked to see how this rolling method would affect the shaping of the crystal structure compared to wire drawing?

Although whether, and to what extent, this difference in crystal alignment, actually shows as having a practical benefit towards the mechanical strength of the wire is another matter entirely.

Also Lafayette, very interesting regarding the medieval fast food.
I guess im more familiar with ancient Romes urban life since it was 'the big apple' of its day.

How much evidence do we have of the Romans having these sorts of production line like setups on a mass scale for making things, in particular the making of metallic items.

and how would the Romans work these lathes? using waterwheels, or maybe even those 'hamster wheels' used in some roman cranes maybe, im assuming a mixture of both is plausible..

if its the former, then those workshops would need direct river access, is there evidence of large metalwork shops on sites close to rivers?
in the same way we might have examples of waterwheel powered grain mills found near rivers.


also im sure this is in everyone minds too but, it also makes sense that different technologies would be used to make iron wire for different applications will change depending on what is needed for, what is intended to do, and how many items per unit of time need to be made, as well as simply what was available.

i mean a massive factory within or close by to Rome itself could more easily adsorb the initially high setup costs of he lathes and making the tubes due to the higher output of rings which makes the costs pay for themselves in time.

on the flip-side a smaller workshop either in the roman provinces, or the medieval Europe a thousand years later, might not make enough maile to justify the initial setup costs and the costs of making the tubes as well..

i realize im thinking with a mindset of modern manufacturing, however limited my understanding is. so this could be entirely wrong in terms of how the romans actually did things..

[David Gaál]

As I was reading this topic I thought about how could one concretely prove that solid mail ring was made from tube? Than something got in my mind: a picture about two rings having various lines in it... and I was searching where I could have seen it... and got it in Vegard Vike's article with the description: "Slag stripes are distributed differently in plan-samples made from riveted rings (drawn wire) than in plan samples made from punched rings (made from sheet metal)". So if there are such slag stripes has someone looked at them in roman mails?
I would be really happy if someone could post up the original text:)

[Dan Howard]

The alignment of slag inclusions can be used to tell how the link was made. Generally speaking, if they run around the link then it was made from drawn wire. If they run across the link all in the same direction then it was likely punched from a sheet of rolled plate. If the slag runs across the link, but not all in one direction, then it was likely punched from a sheet of hammered plate. If they run through the link so that only the ends are visible on the surface then the link was cut from the end of drawn tubing.

[David Gaál]

"If they run through the link so that only the ends are visible on the surface then the link was cut from the end of drawn tubing."
So as I thought slag might tell how it's made? How many pieces were found from that type? And if it was used in roman times why not used in middle ages, or was it just I don't know about it?

[Dan Howard]

[William P]