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Thread: Correct depth

  1. #1
    Join Date
    Apr 2015
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    66

    Default Correct depth

    Hello,

    I am just begining to set CZ's , then hopefully on to precious stones. I love the flush gypsy setting but one thing I am finding difficult ,is getting the correct depth when I use a Ball burr. Sometimes its too shallow, then on one occassion, I nearly went through the ring !!

    I get that judgement comes with experience but as you'll appriciate, if I could pretty much get it right from the off, that'd be an advantage

    I have seen " Stone setting depth collets " which seemingly ensure that I couldn't drill down into the shank too deeply, but how do they (And do they) work ?

    Thank you

    Skie

  2. #2
    Join Date
    Jun 2010
    Location
    Cardiff
    Posts
    988

    Default

    Generally I go half way down the depth of the ball burr before switching to a setting burr, then trying the stone. If it's a noticeably shallow stone, I'll stop before half way. You need to make sure your ring is thick enough and wide enough to take the stone though. Have you got an example?

  3. #3
    Join Date
    Sep 2014
    Posts
    2,052

    Default

    I just go in increments until it sits right so practise makes perfect

  4. #4
    Join Date
    Dec 2009
    Location
    Central London
    Posts
    7,454

    Default

    In all this it is helpful to have some callipers, because the total depth of the stome from table to culet will allow you to match stone to depth of metal without poking through.

    Next it is common when setting faceted stones, for the pilot hole which can be about one third of the diameter or the stone to go right through the metal.

    Lastly as a rule of thumb a faceted stone is deep enough to set, if the table is flush or only just above the metal rim. By viewing it from the side, you will also note whether it is level or wonky. Dennis.

  5. #5
    Join Date
    Jul 2009
    Location
    Romsey
    Posts
    4,795

    Default

    For smaller stones - 3mm down - I look to have the table level with the metal. As a rule of thumb, I'll go to a depth of 2/3 of the diameter with a ball burr, then open out the culet with a couple of smaller ball burrs. I very rarely use setting burrs. Visual inspection of the stone under magnification is important - some have utterly atrocious cuts (wonky tables, wedge-shaped girdles, overly wide pavilions - esp. sapphires) so you need to be aware of them.

    Using ball burrs does give you a few things - including lower costs, options on levelling wonky stones and 0.1mm increments.

  6. #6
    Join Date
    Apr 2015
    Posts
    66

    Default Ball bur

    Hello,

    Sorry to repeat a question...Maybe I have not asked it clearly : I am just starting to set stones, I am trying the gypsy setting, where I have to drill the depth of the entire stone (Table to Pavillion) into the shank.

    Using a ball bur, I am going down ,stopping and I keep checking the depth but what I am worried about, is drilling down that bit too far and making one setting slightly deeper than the rest.

    So is there a fool proof way to avoid this ? Or is there a type of depth gauge tool that I can buy, to clamp on/attach to my pendent drill, like ones that are availiableto attach onto the side of a normal sized hand drill ?

    Thank you

    Skie

  7. #7
    Join Date
    Dec 2009
    Location
    Central London
    Posts
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    Default

    We tried to answer that question yesterday:http://www.cooksongold.com/forum/showthread.php?t=9067,

    The depth you want is from table to culet. It is common to drill right through with a twist drill to make the pilot hole, although you can opt not to if the metal is thick enough.

    There is no specific depth gauge, though you could mark the end of your twist drill with a fine sharpie.

    That said it is somewhat irrelevant, since the stone must be immersed until the table is flush. Many of us use a measured ball burr the same diameter as the stone, to continue until the full diameter is just reached.

    Peter has explained how he finishes just with round burrs, but for a beginner, contiuing with a setting burr allows you to see better how far down you have gone. You then try in the stone and check repeatedly, going in further until the table is flush.

    Usually this is when the side of the setting burr is about two thirds to three quarters immersed. Dennis.
    Last edited by Dennis; 27-11-2017 at 01:48 AM.

  8. #8
    Join Date
    Dec 2009
    Location
    Central London
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    I worry that my post above might still not answer your question, so I have attached images of stone setting burrs.
    They are expensive, so are best use just at the very end, to refine the shape of the seat and save on wear.

    You will see that in profile they mimic the shape of a faceted stone. Inserted too little and the sone will stand proud. Inserted too much and the sone will be too deep.

    The walls are straight and parallell. Gradually inserting the burr until from two thirds to three quarters of the walls are submerged, trying the stone as you go, is the best way to get the depth right. Dennis.
    Attached Thumbnails Attached Thumbnails Stone setting burrs..JPG  

  9. #9
    Join Date
    Sep 2014
    Posts
    2,052

    Default

    I thought I had seen a depth gauge that comes as part of a ( rather expensive) setters package?
    Cant seem to find it atm but Im sure I saw a set that had depth gauges that attach to the burr in some way?
    I think I even watched a video showing how it was used on pave work.
    Tbh it seemed like an awfully high layout for something that does come with practise anyway.

  10. #10
    Join Date
    Mar 2016
    Posts
    116

    Default

    There are these, I have a set, but I have never used them so can't vouch for their usefulness:

    It was a case of 3.95, cheap, so may as well buy them, they might be useful one day (a bad habit).

    https://www.cousinsuk.com/product/st...-depth-collets

    Click image for larger version. 

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    Last edited by Paul Kay; 27-11-2017 at 03:45 PM.

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