[Jewelry making - Article 00159] - Re: [Orchid] Silver shoots all over the place

[Karen Goeller]

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Hi Seyed,

    I'm not familiar with the specific machine you're using for your
    casting, but I can make a couple of suggestions as to where to look. 

    1. Check the counterbalance weight for the size of flask that you're
    using. On all centrifugal casters, you have to balance the weight of
    the flask against a counter weight that's roughly equal - otherwise,
    things will go flying all over. For some machines this is simply a
    matter of moving the weight on the end of the casting arm that's
    opposite where you put the flask (usually held in place by some sort
    of set screw or latch). 

    2. Check the size of the saddle in which the flask rests to make
    sure it's correct for the diameter of the flask. One that's too small
    won't hold the flask steady. One that's too large will let the flask
    roll around in it and off to one side, so the silver never gets into
    the sprue hole. 

    3. To handle the issue of the flask "popping up", we've used thin
    brass strips (about 1/2 inch wide, probably 24 or 26 gauge, about 8 -
    10 inches long), which go over top of the flask, then tuck under the
    two "arms" that hold the saddle in place. Doesn't even have to be a
    really tight fit, but it's enough to keep the flask down. 

    4. This is really a no-brainer and I'm assuming you've done it, but
    will say it just in case. Check the alignment of the crucible's
    outflow hole against the bowl in the base of your flask. It should be
    as close as possible and the crucible holder should be tucked up
    against the base of the flask or as close as you can get it. There's
    less chance of metal spraying out that way. 

    5. If none of the above have any effect, take another look at how
    your flasks are sprued. The bottom of the plaster should have a nice
    "bowl" or cave in it, at the bottom of which is the large opening for
    the center tree of your sprue. You may need to either use a larger
    center trunk sprue, or enlarge the bowl feeder sprue (where the
    button forms at the base of your tree). 

    6. I guess the only other thing to look at would be flask
    temperature. Your flasks should be at about 900 F when you put them
    in the caster and start to melt your metal. I try to direct my torch
    flame during the melt process so that part of it shoots out the hole
    in the crucible and into the sprue hole in the flask, which helps
    keep the investment at temperature. If the flask were too cold, I can
    imagine that the metal could freeze before going into the flask,
    which would stop it up and could cause it to spray all over. 

    Hopefully, some of these will point you in the right direction to
    solving your problem. 

Happy casting!

Karen Goeller
No Limitations Designs
Hand-made, one-of-a-kind jewelry
www.nolimitations.com
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