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Metal lathes for spinning Coolus helmets and such
#1
Hello all,

First time post here... I would like to find out more about the lathes with which the Coolus and other bowl-shaped objects were spun. Most of my searches for Roman-era lathes turn up the bow-type which looks to me like it would be for turning wood, not metal.

The only design I've seen that looks feasible for producing sufficient power is pictured at the bottom of this website: http://www.historicgames.com/lathes/related.html .

What is the consensus here? Does this represent a feasible idea of how the Romans would have spun metal, or is there some evidence out there that I am missing?

Thanks very much!

--Kelsey McLeod
Kelsey McLeod
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#2
I haven't gone deep into this subject but I've the impression that most Roman helmets were raised instead of spun.
________________________________________
Jvrjenivs Peregrinvs Magnvs / FEBRVARIVS
A.K.A. Jurjen Draaisma
CORBVLO and Fectio
ALA I BATAVORUM
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#3
Apparently the coolus types were spun and some others, so i have heard.
I believe there are still signs of the spinning evident in the bowls.
Visne partem mei capere? Comminus agamus! * Me semper rogo, Quid faceret Iulius Caesar? * Confidence is a good thing! Overconfidence is too much of a good thing.
[b]Legio XIIII GMV. (Q. Magivs)RMRS Remember Atuatuca! Vengence will be ours!
Titus Flavius Germanus
Batavian Coh I
Byron Angel
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#4
Quote:Apparently the coolus types were spun and some others, so i have heard.
I believe there are still signs of the spinning evident in the bowls.

And on pateras and some jugs as well. As the drive would have to be continuous rather than the backwards/forwards motion you get from a strap/pole/bow lathe so it seems likely that the lathe would have been driven from a seperate wheel.

There's a conjectural picture of one in Earwood's "Domestic Wooden Artefacts in Britain and Ireland From Neolithic to Viking Times", which touches briefly on the subject.
"Medicus" Matt Bunker

[size=150:1m4mc8o1]WURSTWASSER![/size]
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#5
They surely had harnessed water power?
What about the camed operation as used on sharpening wheels, you know the old foot operated ones?
That would also translate into a continuous rotation?
Visne partem mei capere? Comminus agamus! * Me semper rogo, Quid faceret Iulius Caesar? * Confidence is a good thing! Overconfidence is too much of a good thing.
[b]Legio XIIII GMV. (Q. Magivs)RMRS Remember Atuatuca! Vengence will be ours!
Titus Flavius Germanus
Batavian Coh I
Byron Angel
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#6
Quote:They surely had harnessed water power?
What about the camed operation as used on sharpening wheels, you know the old foot operated ones?
That would also translate into a continuous rotation?

Harnessed water power? Well if they hadn't then those water wheels were a big waste of time. :wink:

Pliny writes about water driven cammed trip hammers being used to pound grain and there's strong evidence to support the idea that trip hammers were used in ore processing and metalworking.

Water power could be used to drive a a 'big wheel' lathe...but so could hand power or even treadmill power. If they could turn stone columns then providing enough power to spin metal obviously wasn't a problem.

Thinking about it though, control/regulation might be an issue with water power. Easier to tell the bloke peddling/turnig the wheel to speed up/slow down/stop then it might have been to disengage from a water driven power source?
"Medicus" Matt Bunker

[size=150:1m4mc8o1]WURSTWASSER![/size]
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#7
On the control/regulation issue, I have a dim mental picture of a wide leather strap clutch around a flat wheel, but I couldn't describe it better. Essentially, iirc, an operator puts more or less tension on the drive wheel by tightening the strap with a lever to produce more or less speed. I can't recall where I saw that mechanism, so I can't be more specific.

I don't think they built complicated pulley mechanisms, though, like you'd see on top of a multi-speed drill press, for example. And we don't find a lot of gearboxes, either, so it would have had to be something more direct and simple than that.
M. Demetrius Abicio
(David Wills)

Saepe veritas est dura.
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#8
Quote:On the control/regulation issue, I have a dim mental picture of a wide leather strap clutch around a flat wheel, but I couldn't describe it better. Essentially, iirc, an operator puts more or less tension on the drive wheel by tightening the strap with a lever to produce more or less speed. I can't recall where I saw that mechanism, so I can't be more specific.

I don't think they built complicated pulley mechanisms, though, like you'd see on top of a multi-speed drill press, for example. And we don't find a lot of gearboxes, either, so it would have had to be something more direct and simple than that.

Gears, friction and toothed are described by classical writers but only in relation to clever gadgets like Archimedes' mechanical plantarium, not industrial processes.

I've got a dim recollection of a mention of some sort of gearing being used to lathe -turn the drums for stone columns but can't remember where it was.
"Medicus" Matt Bunker

[size=150:1m4mc8o1]WURSTWASSER![/size]
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#9
There are Roman illustrations showing a Hamster type cage that was used for raising or lowering stone blocks for building work, these were operated with people walking in them and could be better controlled than useing animals for such work.
Brian Stobbs
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#10
HereĀ“s a reco from Aalen.
Christian K.

No reconstruendum => No reconstruction.

Ut desint vires, tamen est laudanda voluntas.
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#11
Is that about half scale?
M. Demetrius Abicio
(David Wills)

Saepe veritas est dura.
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#12
I do not wish to stray too far off topic here but a couple of earlier comments tend to conflict, this is where Jurjen mentions about most of these helmets being raised and Byron mentions about spin marks that have been traced.
I may be inclined to agree with both here however as far as spin mark evidence is concerned this might be more towards Montefortino styles than Coolus, for indeed when we check out most Coolus types as shown in H. R. Robinson we find that so many of them show evidence of damage 1/3 the way up the bowls and there is reason for this.
These damaged areas indicate that most Coolus type helmets are taken down as opposed to being raised on a stake.
Brian Stobbs
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#13
Thank you everyone who provided their insight on this topic.

So what I gather is that, as far as metal spinning, the use of a large wheel providing continuous rotation and large enough to give significant drive is indeed feasible and historically correct for shaping coolus, patera, etc. I may attempt to reconstruct a lathe of this kind to see what kind of difficulties I encounter. If I actually manage to get some type of bowl out of it I'll be sure to share it here in the forum.

Thank you for pointing out that spinning was not the exclusive method being used, as well.

--Kelsey McLeod
Kelsey McLeod
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#14
[Image: DSCF0031.jpg]

Here is a remarkably intact Coolus.
Visne partem mei capere? Comminus agamus! * Me semper rogo, Quid faceret Iulius Caesar? * Confidence is a good thing! Overconfidence is too much of a good thing.
[b]Legio XIIII GMV. (Q. Magivs)RMRS Remember Atuatuca! Vengence will be ours!
Titus Flavius Germanus
Batavian Coh I
Byron Angel
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