[Jewelry making - Article 00359] - Re: [Orchid] [Source] Opal cylinder

[Thejewelmaker]

========[ Invite a Friend - http://www.ganoksin.com/invite.htm  ]========

Kevin

    Just in case the centerless grinding setup doesn't workout for you I
    thought that I would pass on another method. When I first saw your
    post I visualized your opal as expensive and beautiful. Something
    that I wouldn't want to either waste or damage. I develop a healthy
    paranoia when working dangerously on rare material and want as much
    care and control as possible. That means that I want the work it in
    my hands and close to my eyes. 

    First block the stone out on a flat lap until you have perfectly
    square rod with the thickness of the finished cylinder. If you are
    trying to recover as much weight from your material as possible the
    corners can remain a little rough, Glue round brass rods about 1 inch
    long (turned to size of the cylinder on a lathe) dead center on
    either end. These are going to be your grinding guides and handles. 

    Paint the four flat sides of the opal with a blue permanent marker
    and lightly scribe a centerline down their length. This will help you
    keep your grinding parallel. Use a wet lapidary machine to rough
    grind the corners off of the opal and pre-form the cylinder. Don't
    grind the brass guides! You will now have round corners with four
    narrow flat sides that still have a fine line running down the center
    of each. 

    Now use a vertical flat diamond lap to finish the shaping, Supporting
    the work between your index fingers and thumbs rolling the piece
    against the lap, keeping the guides parallel to the lap gradually
    working the high areas closer to the brass guides and creeping up on
    the center lines. You can roll with the lap or pull against it
    depending on how you feel it cutting. Don't take heavy cuts, keep the
    lap wet and work continuously around the piece attempting to reduce
    each corner gradually by the same amount with each pass. When done
    the brass guides should just about be in continuous contact with the
    lap and the scribed line almost beginning to disappear. Switch to a
    finer lap to finishup and then polish. Sounds time consuming but in
    fact it goes pretty fast. If you have experience at this type of work
    you could skip bluing and scribing, and just roll lap it by eye to
    match the brass guides. 

    I have an 8" lapidary setup but use the accu-finish tool grinder
    with a wet sponge for this type of work, the worktable makes a
    perfect hand rest and the speed is about right, 300rpm. The link
    below will show you the machine. Any flat diamond lap should work. I
    also use the accu-finish for grinding lathe tools, gravers, brass,
    nickel silver, soft gemstones and even the occasional piece of wood. 
I
    true up gold and silver castings, and square flat work on it as well.
    It is one of the most useful and used tools in my studio.

    http://www.accu-finish.com/seriestwo.html 

Good Luck
Dennis Smith - thejewelmaker
____________________________________________________________________
T h e   O r c h i d   L i s t
Open Electronic Forum for Jewelry Manufacturing Methods and Procedures
____________________________________________________________________
Orchid FAQ:
~ http://www.ganoksin.com/orchid/faq.htm
Orchid Archives:
~ http://www.ganoksin.com/orchid/archive
Orchid Galleries:
~ http://www.ganoksin.com/orchid/gallery.htm
Invite a Friend:
~ http://www.ganoksin.com/invite.htm
____________________________________________________________________
Tips From The Jeweler's Bench - Article Archive
~ http://www.ganoksin.com/borisat/tip_sear.htm
The Jeweler's Selected Bibliography List
~ http://www.ganoksin.com/jewelry-books
Buy Orchid Jewelry:
~ http://www.ganoksin.com/shop
____________________________________________________________________
-Unsubscribe:
-Email: orchid-request AT ganoksin.com Body=unsubscribe subject=blank
____________________________________________________________________