Ancient machines and techniques for spun bowl helmets?

[jkaler48]

So what is the evidence on what the machines that did the spun bowl helmets
like the coolus? I am thinking that some information has been found in literary references and from digs as well as by examimation of the helmets themselves. Has anyone built a reconstruction of a spun bowl helmet machine? Are the modern methods used by Deepeeka and others anything
similiar to the orininal methods?

[PhilusEstilius]

I would say that most Coolus helmets were not spun bowls but hand beaten, this comes from experience gained over many years of hand beating many bowl shapes. Indeed if we examine H. R. Robinson on his section on the Coolus this can be verified, for most indicate it by the way they show wear and holes one third of the way up the bowl which is the thinnest and weakest point of these helmets.

[Martin Moser]

Perhaps you might find something in this book:

Mutz, Alfred. Die Kunst des Metalldrehens bei den Römern. Interpretationen antiker Arbeitsverfahren auf Grund von Werkspuren. 1972
ISBN-13: 9783764305734
ISBN: 3764305738