You make an iron frame of similar size & thickness to the one
described above, but of sufficient length to enable it to hold not
only the two dies, _taselli_, on which the medal is cut, but also the
female[108] screw of bronze. This screw is set beneath the male screw
of iron;[109] one ought really to apply the term screw, _vite_, to
this male screw only, the female screw being called _chiocciola_. The
male screw should be three fingers thick and its threads[110] square,
because it is stronger thus than of the usual shape. The frame has to
have a hole in the top of it to admit of the screw passing through
it. When you have placed your dies, _taselli_, beneath the screw,
with the metal you propose to strike between them, you tighten them
up by the insertion of iron wedges[111] so that they cannot possibly
shift. You will find this necessary owing to the greater size of the
bronze screw.[112] Then having prepared a piece of beam about two
cubits long, or more, you fix an iron rod of sufficient thickness and
of about two cubits in length to the lower end of it, and it must fit
into the beam;[113] then fix your frame into a cutting in the head
of the beam made exactly to hold it. It is necessary, too, to bind
the beam round with stout iron bands to give it strength at the place
where the frame is set in, and to prevent it from splitting.
Round the head of the screw must then be fitted a stout iron ring
with two loops to it, & these have to be made to hold a long iron
rod or bar,[114] say six cubits in length, so that four men can work
at it, and bring their force to play upon your dies and the medal
you are striking. In this method I struck about one hundred of the
medals I made for Pope Clement; they were done in the purest bronze
without any casting, which, as I told above, is necessary for the
process called _coniare_. I advise every artist to note well this
method of striking with the screw, for, though it be more expensive,
the impressions are better, and the dies not so soon worn out. Of the
gold and silver medals I struck many straight off without softening?
them first; & as for the cost, perhaps after all it only appears
greater, for whereas in the method of striking with the screw[115]
two turns of the screw will complete the medal, in the method of
striking in the _coniare_ process at least one hundred blows with the
stamps are necessary before you get the desired result.
[Illustration: Diagram illustrating the process of striking medals
with the screw
D. DIE
M. MEDAL
AT ‘A’ WOULD COME THE FEMALE SCREW, AND THE WEDGES WOULD COME AT THE
SIDES OF THE DIES.]
FOOTNOTES:
[108] _La vite femmina._
[109] _Il mastio di ferro_: i.e., _so that the male screw can fit
into it_.
[110] _Pani._
[111] _Biette._
[112] _Gli e di necessita che per la grandezza della chiocciola di
bronzo, la quale ha da essere fatte in modo che la non balli nella
staffa._
[113] _A quella si attacca nella testa di sotto un pezza di corrente
... e bisogna che sia commesso in nella testa di sotto nella detta
trave._
[114] _Cioè a un lungo corrente._ _I give on the next page a diagram
of what the upper portion of this machinery was probably like. Or it
may be as Prof. Roberts-Austen shows it in the drawing in his Cantor
Lecture on Alloys, Society of Arts Journal, March-April, 1884._
[115] _Colpi di conio._