Your description of ancient methods got me curious, and then that
Cellini had written a techniques book! So I searched to see if The
Craftsman's Handbook was available in my county cooperative
library, and indeed it is, but written by Cennino Cennini.
Yes I own copies of works by both Cennini and Cellini, and I tend to
switch the names around when I’m referring to them without the books
in front of me (an odd mental block…go figure…). If you read
Cellini’s treatises and autobiography; lets just say his opinion of
himself was fairly impressive, and he regularly dished on his
contemporaries and predecessors. It just goes to show that artistic
ego is nothing new.
The correct citations: Cennini, Cennino D’Andea, The Craftsman’s
Handbook, circa 15th C. Trans. by Daniel V. Thompson, Jr., 1933, 1960
ed. by Dover Publications, New York (ISBN 0-486-20054-X)
Cellini, Benvenuto; The Treatises of Benvenuto Cellini on
Goldsmithing and Sculpture; 1568; Trans. by C. R. Ashbee; 1967,
Dover Publications, New York (ISBN 0-486-21568-7)
I suspect that after cutting, and cutting, and cutting ---- and
cutting to do inlay and mosaic work, folks will get over the ideas of
“pins” and grooves and the like and just do it like it’s always been
done. It ain’t broke and it don’t need fixin’ ;}
There’s been some interest in the place in Firenze that I have on my
blog -somebody else found it the same way - walking down the street -
somebody else wants to go there sometime. Of course there are others,
and much work around Italy. But we found the card in our pile of
Italian things…
imosaicidilastrucci.it is their website, The address is Via dei
Macci, 9 50122 Firenze. Italian street addresses are in some strange
code, to American sensibilities - at least my own. Again ;}
Staying on the glueless theme… would chill fitting into a silver
base make a lasting glueless assemblies?
Say I created vertical cylinders made of various forms of gem quartz,
cylinder diameter about .011 inch typical. I then machine a silver
base for the cylinder and drill holes about .010 inch diameter, about
a thousandth of an inch narrower. I then heat the silver base to
approximately degrees such as in a toaster oven. Heating the silver
should cause the drilled holes to expand sufficiently to admit the
cylinders. When the base cools, the silver should “lock” around the
quartz cylinders. Right?
When the base cools, the silver should "lock" around the quartz
cylinders. Right?
You HAVE to get the coefficient of expansion numbers dead right
(quartz is brittle) and don’t leave the thing in a hot car on a sunny
day. I have played with shrink fits with metals, often a very elegant
solution but there is almost no tolerance for error.
When the base cools, the silver should "lock" around the quartz
cylinders. Right?
One would think, Andrew. Believe it or not, there’s some risk of the
stone cleaving under the pressure, depending on the pressure. 1/10
mm difference is going to be a lot, more or less, on that scale. But
that’s not really intarsia, it’s just straight inlay… Intarsia
suggests different things to different people, but one thing is
always is is stone-on-stone.
drill holes about .010 inch diameter, about a thousandth of an inch
narrower.
This technique works well with hard metals like steel but could be
problematic over time with a soft metal like silver. For any shrink
fit like this, 1 thou is too little - 3 or 4 thous at least are
necessary but how will you know what the actual size is when you have
drilled the hole? Just using a twist drill or a burr won’t work as,
even if a twist drill is ground truly concentric which is rare,
drilling into soft metal usually leaves a pentagonal hole due to
chatter. The only way to successfully use this technique in silver
would be to drill an undersized hole, ream it out to just less than
the final size and finish it by pressing a hardened steel pin through
the hole which has a tapered portion followed by a smooth parallel
portion which is to the exact finished size. This will leave the hole
truly round and with sides hardened by having been compressed a
little.
What You are proposing is a differential temperature shrink fitting.
As a millwright it was a stock in trade job for me. If you could do
this consistently, You had a job. We commonly worked with pumpkin
sized components.
To shrink a component with a hole in it 0.9995 to 0.999 inches in
diameter on to a shaft or pin 1.000 in diameter, You need to heat the
component to app. 400 degrees F. or chill with dry ice and alcohol to
minus 200 degrees F.
The diameters were carefully checked and polished. Nothing was left
to chance. The scale remains the same getting smaller so for a pin of
0.010 you would need a component with a hole 0.09995 to 0.0999. so
You see there is little way to measure the holes or pin diameters
with enough accuracy. We used GOOD micrometers.
It is a shame as this manner of attachment is nearly as secure as
welding. There is also a likelihood that the component or pins (if
not good steel) may shatter. (This is from under my hat so while the
numbers might not be precise, the scale should be close.)
well, i did one piece, large, set using a groove around the
circumference of the stone and a precisely made ring. Basicallly it
is a reverse channel set, the stone appears to 3 dimensionally
‘float’ above the metal to which it is attached.
in the photos, the stone is about 3.5 inches in diameter, but carved
thinly so it weighs about 180 carats.