Gauge of Back plates

[Sheen]

Hi everyone, I've been making gemstone backplates for pendants and rings in 0.5mm sterling silver sheet for some time now. I'm interested to know what everyone's favourite gauge mm is for this task. For the bezel more often than not I'm using 0.4mm fine silver. I'm pretty sure that was Dennis' recommendation on this forum. Thanks Dennis

[Dennis]

Hi Sheena,
Much depends on the size of the stones: a 3.0 mm stone can happily survive on a 0.5mm backplate.
For a 15.0mm stone, it would be a bit flimsy.

Also for a pendant there is much less strain on the metal backplate. For a ring the shank is connected there, so it is subject to much more twisting and banging when in use.

I know you like rules, but in the end you will have to use judgement, or take time out to test some pieces to destruction.
Kind regards, Dennis.

[Sheen]

Thanks Dennis, I've just been given a ring commision which involves a 3 1/2 cm by 2 1/2cm carnelian cabochon in an open backed setting. I was thinking of maybe using 0.8mm silver sheet for the backplate. It's a bit of a guess as I've never made anything that big before.

[Dennis]

Yes, that feels about right to me too Sheena. Quite a statement ring. Dennis

[CJ57]

That’s what I would use too

[Dennis]

It occurred to me that a large ring like that needs gentle application of a large torch, possibly in a darkened area, for fear of melting the bezel material.
You might consider a slightly thicker bezel, say 0.5mm, soldered onto the backing with easy solder, and then onto the shank with extra easy. Do not quench as that might cause it to distort, but allow to air cool.
Practice with copper first to understand the snags. Let us know how you get on, Dennis.

[Sheen]

I was going to practice on copper as I've never used 0.8mm silver for a backplate but when it came down to it I was too impatient. I woke this morning and just wanted to have a go. As it turned out the bezel soldered to the backplate like a dream. Previous times using 0.5mm it's difficult to get a large piece up to heat and not overheat. 0.8mm was much easier getting up to heat evenly. Next up is to solder on three tube settings.

[Dennis]

If your screen is fogging up, it' because we are watching with baited breath.

[Sheen]

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This was my soldering set up with the titanium trivet from cookson

[Sheen]

She wants a shank like this. Tried it out in copper first to see if it was do-able.
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[Dennis]

Interesting. When you try it with the stone in, you might need to file and sand the front of the shank before soldering on the bezel cup, or the whole thing could be too google eyed and protruding.

[Sheen]

It was all going so well. Got everything positioned and soldered down, the backplate oxidised, the main stone set. But coming to the three tube settings, I got the first stone in but now it's flipping in it's setting. It won't come out either. Any advice. I am using 3mm round smooth cabs. I was using round burs to cut the seat.

[Dennis]

Well, small cabs are known to flip over under pressure, so you definitely need a flat ledge to support them.

Some suggestions:
1.Try get the cab the right side up by manipulating it say with a matchstick, blunt cocktail stick or blunt bamboo skewer with a little beeswax melted onto the end. even BluTack might work.
Then keeping the cab in place with a fingernail, lightly pinch the very edge of the tube with small round nosed pliers all the way round to tighten it.

2. If you prefer to get the stone out, because it is quite loose, it might come out with sticky tape. You need to get the kind of tape used to stick picture hooks to walls, or a small roll of No More Nails Tape.
Upright the stone as above, stick about 1.5-2.0 cm of tape firmly onto the dome of the stone. Leave for 5 minutes or more. Then hold tight and give the doubled up ends of the tape a sharp tug. This often works even if you have to try once more.

The remaining option of unsetting the stones and starting again is too painful to think about, so I hope you will succeed. Dennis.

[Sheen]

I tried to get the stone to sit flat but unfortuneatly it wouldn't, so eventually using a rod I pushed the stone out. Then I sanded the top of the tube setting down a little to get rid of the curving in sides. This time I used a round bur then switched to a stone setting bur to give it move of a ledge. Pressed all the way round with a square bezel pusher. Set all three stones, feeling relieved. Will post some photos later.

[Dennis]

Yes that's a great relief, but also a lot learned for next time.

[Sheen]

Some photos of the making process. It turned out better than I could have imagined. It's quite weighty but within acceptable levels I believe. Maybe I would use slightly thinner wire for the shank next time. I loved using 24ct gold on the backplate, that was a real treat.
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[CJ57]

That’s a bonnie ring Sheena, it’s turned out really well

[Dennis]

That's a splendid ring Sheena and it could become a family heirloom.

[Sheen]

Thanks Caroline and Dennis. It was out of my comfort zone. I find it surprising that I actually made it.

[Petal]

That is absolutely gorgeous Sheena!!! It has been lovely seeing all the progress shots too.

[Sheen]

That is absolutely gorgeous Sheena!!! It has been lovely seeing all the progress shots too.

Thankyou Jules, a client can really push a maker to a new level