Fibula trouble...

[tDub248]

Hey guys, I'd really like to understand this fibula better - how does this hinge mechanism work? well, not so much the hinge as the spring Mechanism. Has an Iron part rusted away? I believe this piece was found at Masada. Anyone have better drawings or photos of it? Thanks so much,

Travis

http://i396.photobucket.com/albums/pp41 ... Fibula.jpg

[tDub248]

does the "spring" come from the bending of the bow part of the fibula? rather than using a form of coiled wire?

[M. Demetrius]

The spring action comes from the pin part itself, on the opposite side of the pivot. If you look, what happens is that little projection above the crossbar presses into the base of the arch, and prevents the pin from rotating further. If the fibula is cast correctly, the point of the pin will not quite reach the clasp. It will have to be bent slightly to fit into the folded part.

The fibula is cast in two parts, the arch and the pin. The crossbar (on the arch piece) has a notch in the middle slightly wider than the pin's thickness. The crossbar has a hole cast into it that goes through the whole thing, and lines up with the hole in the pin. Then a rod is pushed through the holes, and peened on the two ends. If you look at the photo carefully, you can see that the "end" of the crossbar is actually a different metal, perhaps softer.

Does that make sense?

[PhilusEstilius]

It is very much as David has explained and the part that has rusted is indeed the hinge pin, for what we find with most Roman hinge arrangements including Buckles is that the hinge pins are made from iron.
This may have some thing to do with the fact one can draw out iron into a wire but not bronze, a bronze hinge pin would need to be cast and life would be more easy to draw out wire push it thro' snip it off and peen both ends to lock it in.

[tDub248]

sweet guys! Thanks! This makes sense now!

Now the question is: If I were to reproduce this, would modern Bronze be too different from Roman Bronze? or Should I go with Brass to get the right "spring" that this needs?

[M. Demetrius]

If you put a little extra copper in your brass when you melt it, you'll get "red brass", which looks a lot more like bronze, but is easier to get. Scraps of electrical wire tossed in with the "regular" brass (like scrap brass from plumbing valves, etc.) will get that look, but still keep the rigidity of the modern brass, so you can get a little springiness. Make sure you leave the hole large enough to accommodate the hinge wire. The larger hole is easier to remove the investment from, as the drill bits are stronger. I have a couple of fibulae with parts of broken bits still in the holes. Can't get them out until it's time to remelt the brass.

[caiusbeerquitius]

If you want to get an "authentic" material, just melt copper and add some tin, but not more than 30%. :-) )

[minvid]

If you want to cast the pin, it will probably become too weak without further treatment. You should use a small hammer to forge the pin afterwards. This will strengthen the metal by compression and makes a good tension.

[tDub248]

Great input guys, thanks!

[Steven M. Peffley]

Hi Travis,

http://www.thorthorshammer.com/hingepinpage.htm

Sean Campbell makes these and other Fibula; i've bought a bunch of stuff from him since i first saw his stuff at Pennsic several years ago. Pretty reasonable prices also.

Steven

[jvrjenivs]

Hi Travis,

http://www.thorthorshammer.com/hingepinpage.htm

Sean Campbell makes these and other Fibula; i've bought a bunch of stuff from him since i first saw his stuff at Pennsic several years ago. Pretty reasonable prices also.

Steven

ah, seems quite interesting. Nice stuff and good prices