Metal screws

[richsc]

When I was visiting colonial Williamsburg this weekend, the blacksmith docent mentioned that metal screws were known to the Romans, and that he had read of that. I know of only one metal screw example in a Pompeii bronze trivet that screwed together, rather like some cheap Walmart furniture. But I have not heard where the Romans might have used metal screws or seen any examples. Anyone know of any examples out there, and if so, how they would have made them?

[Medicus matt]

Some of the 'onion heads' on crossbow fibula were threaded and screwed on.

[Robert Vermaat]

Matt is right.

http://www.metmuseum.org/collection/the-...286?img=14


[attachment=10173]screw.jpg[/attachment]

[Medicus matt]

Matt is right.

That's what it says on my business cards.

http://www.britishmuseum.org/research/co...id=1362840

[Walhaz]

Since thanks to Robert Vermaat and Medicus Matt I now know that the Romans had metal screws, how common were they? The fact that the above piece is made of gold seems to indicate that it was made for someone with a good deal of money. Do we have widespread examples of metal screws from throughout the Empire? Or was it something only the most wealthy could afford?

Or did the Romans just have their own method of securing things and not think it was worth it to further develop metal screws?

[richsc]

As fasteners they were not common at all. Iron nails and peening were the common fastening methods. Screws were apparently used for a variety of other purposes though, like the collapsable table, the speculum, the wine press, etc. But fasteners all seem to be for jewelery as really show off types of things. If someone knows or can find screws in any other fastener that would be great to see. I would be interested to know if the Antikytera mechansim has any screws in it, as it might occasionally need to be disassembled for maintenance.

That was the point of the fellow in Wlliamsburg: if a mechanism might need maintenance they used screws: otherwise nails.

[Q Rutilius]

The Romans had pumps. Over time pumps require maintenance. So, I wonder, did they assemble them with screws

[Crispianus]

An Archimedes Screw, a pump built with this would not need to rotate in a tube its only necessary to rotate the tube with the screw fixed inside the only maintenance necessary would be to occasionally re-grease or replace the bearings at the ends.

The cross bow brooch screw I think could just use a pin for the internal "screw" although I don't recall seeing one. The construction of the thread could be a piece of square wire wrapped round a rod and hard soldered together, this I think could be done on a larger scale with iron and forge welded together.

The Nail hoard from Inchtuthil containing 800,000 nails presumably for construction, included to my knowledge not a single screw.
http://www.romanscotland.org.uk/pages/na...lhoard.asp

Theoretically and Practically though its possible for a Roman Blacksmith to make a Tap and Die for producing a matching internal and external thread for nuts and bolts etc Providing a suitable piece of steel is available for the purpose.
However a plain wooden or metal "bolt" with a wedge in the end is far simpler and would serve the same purpose as a threaded Nut and Bolt although made for a single purpose, this I've made on numerous occasions largely to hold loom and lathe parts together so they can be easily assembled/disassembled.

[Medicus matt]

I've seen at least half a dozen examples of crossbow fibula with threaded shafts and onion head 'nuts' and, for all I know, it was a common method of manufacture.
What I find interesting about them is that, under normal circumstances, this element of the brooch was totally hidden so it's obviously not done for show. It's done because it was the best way to achieve a practical end.