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Thread: wide band ring sizing troubles

  1. #1
    Join Date
    Oct 2015
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    Default wide band ring sizing troubles

    Hello all,

    I am having some problems with sizing metal for making wider ring band.

    I've been using the formula of multiplying the thickness of the metal by 3 and then adding it to the circumference, plus 1-2mm for end straightening. This seems to work fine for thin rings of about 1.5mm but when I did exactly the same thing for a wider band (4mm) it ended up multiple sizes too big (an attempted size U ended up a massive size 1 - 6 sizes too big)!

    I suspect perhaps hammering a wide ring on a tapered mandrel is stretching as it's being hammered? Is there any other tool I should be using to round a wide ring (i.e. a tool that's not tapered) or is there some other solution?

    Still a newbie so apologies if there is something obviousl I'm missing here! Grateful for any help with this.

  2. #2
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    Not sure I quite follow the reason you're adding 2mm? I recently made a ring in 8x2mm silver using the formula pi*(diameter + thickness) and it came out the right size.

    If you're using a steel hammer on a ring mandrel then there's a good chance you'll stretch it; I use a rawhide or UHMWPE mallet (yes, I can tell the difference - just depends which is closer) to finish rounding rings, flipping them over to even it out from both ends.

  3. #3
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    Hi Peter,
    Thanks for reply. I'm using a rawhide mallet and fliping it over to even it out so doesn't seem that's the issue.
    I'd been told to add 1-2mm to calculation to allow for straightening the ends of the silver before making the ring, but actually I only added 1mm on the one I described anyway so that doesn't account for the massive size increase either.
    It seems the mystery continues....

  4. #4
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    Do you have a record of the measurements you used? Just to cross-check.

  5. #5
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    It was my understanding that it is Pi plus the metal thickness only

  6. #6
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    Oct 2015
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    Hi, sure :
    Attempting to make a U size (62.7mm) ring using 4mm wide/1.3mm thick silver wire:
    So I did (1.3 x 3) + 62.7 + 1mm = 67.6, rounded up = 68mm length of metal.

  7. #7
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    My charts list U as 62.89 (20.02 diameter); pi * 1.3 + 62.89 = 66.97mm (67 nears as makes no difference).
    I still don't follow the need to add on 1mm... If anything, it's preferable to make a ring fractionally small and stretch it.

    Can't see how that would land you 6 sizes off - 1, yes, but not 6! Z+1 would need just over 74mm of metal.

  8. #8
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    Yeah, I know, makes no sense even with the unnecessary extra 1mm.

  9. #9
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    Dear Elizabeth,
    Most people take the size of wide rings to be half way between the two edges on a ring stick. However when using expensive metal, it is worth making it in brass or copper first to verify the size.

    As far as the length of metal is concerned, please have a look at Andrew Berry here and use the maths only a guide.

    https://www.youtube.com/watch?v=xaU5acww9gc Dennis.

  10. #10
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    Oct 2015
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    Thanks Dennis, yes, have seen the Andrew Berry video and it does look a good method, I will give it a try. Out of interest, which method/tools do you use for bending?
    The only thing that puts me off is the extra metal cost if working in something expensive - an extra 10mm (5mm on each side) in silver isn't too bad but would be quite a lot in gold.

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