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Thread: Sizing collets

  1. #1
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    Default Sizing collets

    Very quick one on getting sizes right for collets -

    Click image for larger version. 

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    The image is based on 17 degree collets, 0.8mm wall thickness and a 6.0mm stone. Left hand pair show a collet sized with the top at the same diameter as the stone, right hand the stone overlaps by about 50% of the wall thickness.

    Getting the top of the stone level with the top of the collet prior to setting leaves about 0.5mm wall thickness on the left hand ones, whereas the overlap version leaves almost 0.2mm. This isn't thick enough to cope with much in silver... That, of course, is with a perfect bearing. If it's fractionally larger then you have even less metal to retain the top of the collet, let alone the stone.

  2. #2
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    Yes point taken Peter.
    My thought then would be, if the collet is tapering and slightly long, you could steady the stone and set it without a bearer at all. Dennis.

  3. #3
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    You can, but life's a bit easier if the thing isn't inclined to wobble as you do it. Additionally, the bearer provides a fractional weak point to encourage the metal to fold over (not much, but slight); depending on the thickness of the collet it can look a little chunky too. Many ways to skin that cat, so long as the too-thin wall is avoided.

    Of course, if the collet is slightly too large it's often a much easier situation to deal with than too small.

  4. #4
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    While I'm at it - asking me to tube set stones in tubes that are just 0.15-0.2mm larger than the stone diameters isn't ideal either. I think some people are trying to drive me to a nervous breakdown...

  5. #5
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    They're trying to grind you down, Peter. Make them get smaller stones. Dennis.

  6. #6
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    If they hadn't been diamonds I could have ground them down As it was, I got the client's go-ahead to use a tapered punch to flare the settings enough to work with them.

  7. #7
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    I am very far from being even a vaguely competent setter, but I really hate setting stones with very thin walls. However, this means I always leave mine too thick which makes it a total arse to push the metal down!

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