Measuring Step Bezels for faceted stones

[angmc]

I'm using what seems to be the generally accepted formula i.e. for the outer bezel diameter of the stone + thickness of metal x 3.14 and for the inner bezel diameter of stone minus thickness of metal x 3.14 but it's just not working out for me. The outer one always turns out too small so I usually end up using that as the inner step but thats not ideal as the solder join is then between the inner and outer so lots of faffing to get them to fit and also the height would be wrong for the inner so that has to be adjusted. Then the stone is supposed to 'fit snuggly' but it never does so lots of filing to get it to fit and then by the time all the soldering has been done the metal has shrunk and the stone wont go in again!! Or by the time I've got the two bezels fitted together they're too big for the stone!

Has anybody got any advise? Is it just practice? It's driving me mad.

Thanks

[Dennis]

Give up the maths is the answer. Buy a cheap set of twist drills, the largest range within your budget and use the stems for standard mandrels. Get 4" electronic callipers to verify what your stones measure. They can be less than £10 on line.

When you wrap your bezel material around the stem of your choice and cut it you will quickly become canny enough to get the size right.

Still too big, cut through again with an 0/2 saw blade to reduce it. A fraction too tight, re-insert the stem and tap lightly on a metal block while rotating to enlarge rapidly, but mostly it will be just right.

You probably know how to allow for ovals. There is so much more to say, so if stuck just ask. Dennis.

[angmc]

Thanks Dennis. I think I am probably getting too caught up in the figures, probably comes with working in accounts in my real life :)

I do already have some digital callipers which I have been using to measure the stones and I've probably got a fair stash of twist drills too, just didn't think of using them for this. I'll definitely give this method a go.

[J Allison]

Or do what I do if the stone is big enough wrap masking tape round the stone for measurement