Clockwork Trilobite – Part 2

Today was just a lot of sawing.  A lot…I had forgotten how gummy and resisting sterling silver could be, especially in thicker pieces.  Now I remember why I much prefer sawing, engraving and carving in steel…

Above are the two trilobite pieces sawn from my two silver plates.  On the left is the top half of the trilobite (and the thickest part) and on the right is the bottom part (the thinner plate).

As you can see, there’s a fair amount of scrap that isn’t useable for much of anything else.  The largest scrap part of the thinner plate (on the right) is still useful, and perhaps the next smaller might eventually find a use, but the small half-moon is only good for silver reclamation without a lot of additional work.  One day, years from now when I have several pounds of scrap, I can send it back to a refiner for the scrap value.  Remelting at this point would remove so much of the alloying copper as oxide scale, slag and pickling depletion, that I couldn’t ethically (or legally…) claim it to be sterling silver without assaying the silver and correcting the alloy.  I doubt I’ll ever find use for the scraps of the thicker (on the left), they’re just too small, but that is the nature of this endeavor.  They may eventually find their way into a little shibuichi (I occasionally alloy and roll my own).

Now to cut out the gears.  The client has requested copper gears for a contrasting color, but in a fortunate turn of events, I discovered a small piece of shibuichi in the scrap drawer.  Shibuichi is a Japanese art alloy consisting of copper and silver, usually one fourth silver (shibuichi means one fourth in Japanese).  This happens to be 25% shibuichi, the standard alloy, and was a test piece for this knife:
The knife scales are patinated shibuichi, which normally turns a dark grey, where copper would more often be blacker.  Shibuichi is a much more exciting metal than copper, so will lend additional interest to the piece.  Shibuichi when freshly polished has a loverly pinky/coppery color, but like copper rapidly oxidizes darker.  So, I’ll cut the gears from the shibuichi.

Above is a closeup of the little knife box, for Dori.  Hope this helps, Dori!

Above is the paper pattern glued to the shibuichi.  I will cut it a little large on the left side, as I intend to undercut the silver top to make the gears appear as if they disappear inside the trilobite.

So, after several broken jeweler’s saw blades (I was something of a klutz today), and a few bad words, you can see all the parts above (minus one  other small gear).  As a technical note, I used 5/0 for the shibuichi and thinner silver plate, and 2/0s for the thicker.

Here’s what I tell clients about maintaining the gear color on the trilobite:  Both copper and shibuichi (and bronze, for that matter) will rapidly oxidize to a dark color from the more desirable coppery color.  There isn’t any coating known to man that will stop this for long, and things like lacquer will just chip and break down leaving that mottled, nasty look after a few years.  So, eventually when the gears turn darker than you like, your mission is to use a “Pink Pearl” pencil eraser and gently rub the dark areas to remove the oxides and restore the coppery color.  I’m sure you remember sitting in history or math class and making an old penny go back to shiny copper with a pencil eraser?  Do this gently – you don’t want to remove so much that the gears look like new copper (or shibuichi in this case), so stop when it gets back to looking good – we need the dark in the recesses to see the lighter coppery color.  Of course, if you remove too much, a month or so will self-heal the problem.  “Pink Pearl” is a brand name for the common pink colored eraser that almost all pencils have, so a new pencil eraser will work fine, just be careful not to let the metal rim scratch the shibuichi.  Don’t use an ink eraser, that is way too abrasive.

Next, I have to flatten the mating surfaces of the top and bottom plates, and then carve out the undercutting recess for the gears in the top plate, all before silver soldering everything together.