Q: What kind of a machine did Faberge' use to engrave the gold under the
enamel on his famous eggs and other irregular shapes?
A: That's done with what's called a straight line engine turning machine.
The work is called engine turning or guilloche work. Engine turning machines
come in two basic flavors. The "round" machines operate like lathes,
while the "straight line" machines are more like shapers. The
round machines produce concentric circular or oval patterns, and are most
familiar as the tools used for pocket watch dials and cases. The classic
application looks like a cross-hatched knurled pattern, made of intersecting
spirals. In fact, it is made up of concentric circular lines, but the lines
have a waviness to them; the intersections of the waves create a pattern
that looks like spirals. The machine that does this looks like a lathe headstock,
and is hand crank powered, except that the whole headstock and bearing assembly
is mounted on springs, allowing it to oscillate from
side to side. Some also go forward and back along the axis of rotation.
In addition to the chuck, a series of rosette wheels are mounted to the
shaft, the periphery of which rides along a stationary "rubber"
piece. That rosette wheel has a wavy or scalloped pattern around the edge,
which causes the whole headstock to move from side to side as it rotates,
following that pattern as it rubs on the "rubber". Then, a hand-controlled
cutting graver is held on the rotating and oscillating workpiece, and a
cut is made that matches the wavy motion of the headstock. The graver is
mounted to a fixture equipped with screw feeds with ratchet stops so the
cutter can be easily and quickly indexed over a discrete distance from side
to side, generating the spacing between cuts.
The Faberge work you've seen, though, is mostly done on straight line engines.
These have a central chuck to hold the work, which can be indexed to rotary
positions as needed (for patterns of radiating lines, for example). The
chuck is mounted on a side to side slide, which is itself mounted on a vertically
moving slide. A hand crank moves the whole apparatus up and down, while
the side to side slide is spring loaded to bear to one side. Again, like
the rotary machine, a rubber or follower bar, mounted to the slide, rides
up and down against a changeable piece of steel fixed to the machine itself.
The edge of that piece has a scalloped or notched or otherwise patterned
edge, and as you crank the vertical slide up and down, the sideways slide
oscillates from side to side following that scalloped pattern. The pattern
piece, by the way, can also be incrementally moved up and down to offset
sequential cut patterns. The
larger wavy moiré' pattern effect is generated by moving the pattern
bar up and down. Meanwhile, with each up and down movement, a hand powered
cutter, set into an indexable fixture just like with the "round"
machine, is brought to bear on the workpiece, creating the cuts. After each
cut, which may be one pass of the cutter, or several passes for deeper work,
the cutter fixture is indexed over to one side or the other, as required
for the next cut, and if needed, the pattern bar is also offset vertically
as might be desired.
Engine turning machines were in use since the 1600's or so (don't quote
that, I'd have to go look up the exact dates and stuff if anyone really
wants, I've got it all somewhere) and were very popular as an ornamental
effect up through the 1930 or so. Art Deco work used it quite a bit. But
the machines are rather labor intensive, compared to the more current "diamond
cutting" ornamentation, and require some skill to really master. Plus,
the style isn't so much in fashion any more. Aside from one Swiss manufacturer,
who I believe is still custom-making these things (for several tens of thousands
of dollars each), they haven't been made since shortly after World War II,
when the English firm, Plante, stopped production. These machines, when
available, are quite in demand even so. Much more common in the U.S., are
smaller, slightly less versatile machines made by a number of manufacturers,
including Hall, and Field. A number of these machines, from the 1920s and
30s are still in daily use at factories like Dunhill, which uses them to
decorate cigarette lighters and pens, etc., or at findings manufacturers.
A regular item in a number of catalogs, for example, is a little tube or
barrel clasp used for neck chains and the like, with a simple engine-turned
pattern on the tube.
In my own work, I discovered engine turning machines while in graduate school
at Tyler, which had an old Hall machine in good restored condition (It's
since been moved out, in favor of their new CNC mill... (sigh)). Using it
first just as a neat way to get really precise scored cuts for folded sheet
metal construction, I quickly got interested in the patterns too, especially
when I discovered the cool possibilities they open up with reactive metals.
So I've now got one too, in my back bedroom (converted to workshop). I use
it mostly with reactive metals, anodizing niobium to one base color, cutting
a loose pattern in it, anodizing to another color in the cuts, and repeating
this with several overlaid patterns. I've found no other technique which
gives me quite the same effect of overlaid glittering colors... And then
there's the "work-efficient" way to decorate a piece of metal,
though the results are quite different... I put nice engine turned patterns
on a number of pieces of Starret flat ground tool steel stock, and use these
for roll printed patterns. You get a pattern of raised lines this way, instead
of bright cuts, but it's still pretty distinctive- and a lot quicker...
For anyone interested in obtaining one of these machines, If you're handy
enough with tools to rebuild an old machine, they are available fairly inexpensively,
once you find one. I paid less than a thousand for mine, but it needed extensive
work to get it running. If I had it to do again, I might have saved all
that work and gone to Gold Machinery in Providence. He's got quite a number
of them sitting around for less than two thousand, ready to run...
Peter W. Rowe M.F.A., G.G.
Commercial and custom jeweler and metalsmith
Graduate Gemologist and Lapidary
Opinions expressed here are solely my own....... and subject to change
according to my mood and the state of my art ....
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