[Jewelry making - Article 00035] - Re: [Orchid] Fine Silver tubing

[Peter W. Rowe]

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>        A technique explained by Anthony James Lugo, (Head of the
>     Art Department, Palomar Community Collage, San Marcos,
>     California). If the chenier was run through the draw plate
>     seam-up, a butter knife was inserted in the seam to prevent the
>     tubing from twisting.  Usually takes a third hand but does
>     work. 

    Yes, but often not worth the bother.  And with metal that has
    any spring, the seam nicely aligns with the butter knife only
    while at that locations, while between the knive and the draw
    tong, it's free to twist as needed should any uneven stresses
    induce it to waste the time you spent setting up the knife in the
    first place.  Among other things, your original blank must be
    exactly parallell and even in thickness.  Sometimes that's easier
    said than done, to the degree required to keep a piece of tube
    from wanting to twist just a tad.  Also, drawing forces must be
    exactly in line with the plate.  Any off-square force, and the
    thing curves a trace.  Even with a good draw bench, that's hard
    to do sometimes.  If your seam is good and tight, who cares where
    it is?  Won't show. 

>        Making long (12 inch) tubing of heavy wall thickness (18 g)
>      is a challenge not to be missed. 

    Tell me about it.  Today I spent half the day wrestling with a
    bracelet in 14K white gold we had to make up.  It has to have
    diamonds burnished in all round, so the wall needed to be around
    .8 mm once finished.  The gold I had to work with is a normal
    casting alloy, not a rolling/drawing one, and it was NOT
    cooperating at all.  Part of the problem was that I was pouring
    the longest ingot I could in our little plate mold.  At a 14 mm
    width, about an ounce and a half, the ingot would look good, but
    from shrinkage, would be ever so slightly thinner in the middle,
    so the initial passes through the rolls seem to have stretched
    the center of the ingot a little instead of rolling it right
    away.  So when curling the blank around prior to starting to
    draw, and then while drawing initially in the plastic plate, it
    tended to crack in the center.  Even once I got it finally
    patched, drawn, soldered and all, it wanted to crack just in
    annealing, even after only one draw (white gold is "hot short",
    meaning that it has little strength while hot, so before
    annealing temps get reached, some stresses can crack the metal as
    you're heating it.  A real pain in the rear.) then, when finally
    drawn round, I needed to convert it to an oval.  Figureing
    exactly which round size would draw down in the largest hole of
    our oval plate, which isn't any too large, I goofed, and started
    one round hole too large, so the force needed to pull through the
    oval hole was too much.  We've got this antique old little draw
    bench with weird little draw tongs.  The serated teeth in those
    tongs are soldered in bits of file, I think.  Always worked well
    until today, where I pulled so hard both those inserted jaws
    broke out.  And then, only while trying to solder them back in
    with easy silver solder, did I find that the idiot who originally
    put em in (before I got there, maybe long before) had done it
    with tin/lead solder of some sort.  Whatta mess.  had to regrind
    everthing clean, and resolder the tongs before I could back the
    tube out, draw it down one more round hole, reanneal, fix the
    cracks formed in annealing, and draw it to an oval.  And I won't
    even start in on the next part, bending the oval heavy tube I
    ended up with into a bracelet, without benefit of any decent
    bending equipment aside from a vise, bracelet mandrel, assorted
    pliers and hammers, etc.  Sheesh, that stuff was so stiff I could
    hardly bend it at all (its a 5.5 mm wide, 3 mm thick, almost 1 mm
    wall thickness, drawn white gold tube, after all.  A rather
    structurally rigid piece of metal.), even with some pretty heavy
    forces...  I got it bent, but not really smoothly yet, and there
    was some twisting as well, that I've not quite figured out how
    to correct.  This stuff just laughs at a pair of vise grip
    pliers.  Tomorrow will tell.  I'll go to work well equipped with
    valium.  (just kidding.)  For what it's worth, this is the third
    such bracelet I've done, so I know it will work.  Somehow.  And
    they're great looking when finished.  But geez whatta bother to
    make. 

    I pass all that along just to help out any of you who think this
    gets any easier, more predictable, or slicker,  as you get more
    advanced in your skills...  (grin) 

    And yeah, I know.  There are better alloys, and other bending
    tools, and better ingot casting methods, and all the rest.  Talk
    to my boss.  The minimalist equipment I had to work with was all
    I had to work with.  Welcome to the industry. 

Peter Rowe

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