[Jewelry making - Article 00240] - Re: [Orchid] Drilling a hole in gold

[Peter W . Rowe]

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    um. Julia, don't use a bur. Use a drill bit... Most burs are not
    "end" cutting very well, while a standard spiral drill bit is
    intended for just that use. You can get drill bits made with 3/32
    shanks to fit quick release handpieces, or standard drill bits that
    fit the adjutable chucks on a #30 handpiece. High speed steel will
    hold an edge much better than ordinary carbon or vanadium steels (like
    most of those 3/32 shank bits are made from), and it won't be ruined
    if it gets a bit too warm. Use bur life or another good drill/bur
    lubricant. If the metal is anything other than quite thin, and you're
    using smaller size bits especially, then drill a little and lift the
    drill slightly before pressing down again (lightly.) That allows
    chips to clear out and lube to get to the tip, reducing drill
    breakage (which is going to happen now and then anyway, especially
    with thicker metal or smaller bits. Remove broken drills by soaking
    in hot pickling solution (sparex or another sodium bisulphate pickle,
    or use grocery store alum, boiling) Breakage is one reason why drill
    bits are commonly sold by the dozen, but to an extent, you can
    resharpen the points on broken bits by regrinding them on the side of
    a fine grit seperating disk or similar tool (or by hand on a fine
    whetstone, but that's hard to do and a PIA...) Your drills will start
    slightly better if you make the indentation with an actual center
    punch type of tool (make a small one in a few moments from an old
    broken bur if you like. The key is that the conical tip gives an
    indentation matching the shape of the bit more than say, a round bur,
    giving a more accurate start to the drill. Pay close attention as the
    drill starts to cut so it stays "on target". If it wanders to one
    side, you can drift it back if you catch it before it's cut too
    deeply. 

    Also, when drilling, turn off the loud music or take off the
    headphones and listen to what's happening. When a drill starts to
    bind, or cut roughly, you can often hear it do it, as well as feel it.
    When that happens, lift the drill out to clear the hole and reapply
    the lubricant before proceeding. Doing this will significantly reduce
    the number of bits you break. Also, keep in mind that like any
    cutting tool, drills get dull. A dull bur just doesn't cut well, but
    a dull drill heats up quickly, stops cutting, and often will figure
    out a way to jam and beak in the hold. So when the bit stops cutting
    cleanly, inspect the tip to see if it's dulled. If so, resharpen it or
    change to another one. Some metals will dull a bit faster than
    others. Platinum, for example, quickly dulls a bit, while golds do it
    less quickly, so you'll get more holes out a bit before it needs
    sharpening. On a recent platinum piece I was drilling prior to
    setting a bunch of diamonds, the particular batch of drills I was
    using yielded only about six decent holes per drill bit before
    becoming too dull to cut well. With practice and good magnification,,
    they're not that hard to resharpen, but it's annoying still... 

    And do note that even with the best of techniques, drilling is
    sensative and can be tricky. We often use very small diameter drills,
    and put holes though materials significantly thicker than the drill
    diameter. That's a stress on big industrial drills and even more of
    one on the small ones we use in jewelry. So if you've got it pretty
    down pat, but still get frustrated by the occasional broken or dulled
    drill bit, then rest assured you're not alone. Just the way it
    happens.

Hope that helps.
Peter Rowe


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