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Thread: Tube setting: advice on setting burr size

  1. #1
    Join Date
    Feb 2018
    Posts
    9

    Default Tube setting: advice on setting burr size

    Hello,

    I would like to attempt a tube setting for the first time. All the guidance I read says that the setting burr needs to be as close as possible to the size of the stone. The stones I would like to set vary from 3.8mm to 4.2mm. I couldn't find anywhere setting burrs with such a range of sizes. Would it be OK to use a 4mm burr for all of the stones?

    Thanks in advance for your help.

  2. #2
    Join Date
    Dec 2009
    Location
    Central London
    Posts
    7,437

    Default

    And to add to your troubles, a collection of graded stones will vary slightly in size. So:

    Get callipers to measure each stone. Electronic 4" ones are the easiest to handle.

    Get a few short lengths of tubing plus and minus the size you think correct. They also will be slightly different from what is described on the site.
    Then it will be easier to sit a stone on the end and choose the tube you need.

    Once prepared, the walls around the stone should be around 0.30mm thick. The table of the stone should be almost flush with the edges.

    Now to talk about the burr. Get a small selection, perhaps three, so that starting too small, you can experiment to see which provides the best fit. Proceed slowly trying the stone several times until it is level and almost flush.

    Lastly, round burrs are cheaper, cut faster and will provide several widths depending how far they are inserted, so you might start with them and change to the setting burrs to finish. Dennis

  3. #3
    Join Date
    Sep 2014
    Posts
    2,049

    Default

    Just to add to what Dennis has said, not only will the stones vary in size but so will the burrs- a burr sold as 4mm for example will be unlikely to be 4mm, generally they are slightly smaller although just for the sake of variety they can also be slightly larger.
    I don't really know why jewellers put up with this, engineers certainly wouldn't.
    In any case, measure each stone and measure your burr and go for a burr that is slightly smaller than the stone.
    I generally just use a round burr , occasionally finishing the seat with a setting burr if needed in which case its best again to go for a slightly smaller size than the stone.
    Tube setting is probably the easiest setting to do but it is imperative that you get the hole exactly the right size for the stone.

  4. #4
    Join Date
    Sep 2014
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  5. #5
    Join Date
    Feb 2018
    Posts
    9

    Default

    Thank you so much Dennis and Enigma. Excellent advice. As always helpful and knowledgeable.

  6. #6
    Join Date
    Sep 2014
    Posts
    2,049

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    You're welcome
    Also, if you find the hole is still too small using a burr that is slightly smaller than the stone and the next burr size is slightly bigger than the stone you can use a round burr that is slightly bigger than the stone but don't put it all the way down to the widest part.
    Personally I think burrs should be available in every .1mm size and all burrs and stones should be exactly the size they are supposed to be, life would be so much easier

  7. #7
    Join Date
    Jul 2017
    Posts
    297

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    I have found that each ball burr I've bought has been 0.2mm larger than the advertised size so it's definitely worth getting a selection, and by turning the burr slowly in digital callipers you'll find that one pesky "tooth" that is fractionally larger than the rest, so never just measure one part of the burr. So yes, get a few.

    It might also help to make an indentation with them in thick copper sheet, use a Sharpie pen to mark on the sheet which burr you used and then use that as a guide when choosing the best burr to set a stone.

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