Making collet from sheet

[newbie2012]

Hello

Is it possible to make, say, a round tapered collet for an 8mm stone from a strip of sheet approx 1 cm x 3 cm, soldered, then punched in a plate?

I'm trying to work out the cheapest way of making one and am comparing tubing, strip of sheet (above), piercing an arc shape from sheet (creates wastage) or doing one in base metal then getting it cast up. Strip of sheet seems to come up cheapest for silver, and casting from base seems to come up cheapest for gold.

I'm struggling with the maths..
Thanks

[ps_bond]

There's another method that gives you your arc - although 10mm is quite wide even for that, that would result in a collet taller than your stone is wide... How deep is the culet of your stone?

Hold your strip in a pair of ring pliers, perpendicular to the jaws and as close to the joint as you can manage. Grab the strip close into the jaws with a pair of flat pliers and pull the strip around the half-round jaw while holding it flat to create the curve. I've been using an arc laid out on paper to compare against; for the larger collets they need a bit of flattening on a block, but it is a low-waste way to create collets.

Whether it is worth doing that depends on how many you're doing, how precise your stones are etc. etc.

[Dennis]

A simple way of doing this is to draw a curved strip on a postcard, using a compass and join the ends with Pritt. When you have got it to your liking, cut it through and use this as a template for you metal (0.4- 0.5 metal sheet is about right).

Once soldered you can perfect it in a collet plate, but shaping it on a fat pencil, such as used for make-up would do. To set the stone, (I presume it is faceted) you trim the metal to be no more than one third of a mm above the rim, bevel the outside of the metal to a knife edge, keep the table of the stone level and push the metal over.

With care the stone will be stable enough without a bearer. Regards, Dennis.

[newbie2012]

Thanks Peter, that's a great help!

(Dennis- thanks, I usually do this, but find there is wastage, so wondered if it could be done from a straight strip of sheet instead).

[Dennis]

(Dennis- thanks, I usually do this, but find there is wastage, so wondered if it could be done from a straight strip of sheet instead).

Sorry, I don't understand that at all, because if you get your paper pattern right, all the wastage is paper. Then you flatten it, and use it as a template.

Stretching a tube to create a cone using a collet plate is quite tricky and creates waste too. Here is a past thread on collet plates, but unfortunately the pictures are missing:
http://www.cooksongold.com/forum/showthread.php?t=3522

[Dennis]

Ah, the penny has finally dropped. You mean waste from cutting curves rather than strip. Well Peter has given you a way of stretching strip around the tapering beak of ring pliers. You could certainly perfect that in a collet plate, or try some other compromise, but it will take practice. The one I have is 17°.

If you are considering gold, then look at Cooksons NB1 272 274 & 275, or NN1271, 272 274 & 275, but the range is limited. Regards, Dennis.

[newbie2012]

Thanks Dennis