Mandrels

Last updated: 12/3/16.  By: Nancy LT Hamilton

Related Webpages

bench-anvil-combo-kit  I found this set on Amazon and thought it was a good starter setup. There’s a ring mandrel, bracelet mandrel, bench pin and a vise to hold them all.  Usually, under $90.00.  If you want it without the bracelet mandrel, there’s also a similar kit that is under $50.00. I haven’t purchased one but, the reviews are really good.

How do I measure ring shank stock for a square or finger-shaped ring?

Here’s a link to a PDF from Finelt.com.  But, I recently did two tests and found that, although the ring size measured approx. 1/2 size smaller, after shaping, it fit like the original size, before shaping.  See my Q & A: Rings page for details.

Making an oval bezel without a matching ring mandrel

Question

I’m trying to figure out how to make a 30x40mm oval for an open-back bezel for resin. The metal is too thick to pass a cabochon through it to shape it the way soft bezels are usually made. I thought it would be so easy to just find a large oval mandrel and shape it like a ring but, I can’t find the appropriate tool. Rio Grande’s staff didn’t have any real ideas. These types of settings are abundantly available, so obviously a factory can make them. But how in the world do I shape a perfect oval without a mandrel?

Answer

These answers are from two emails.

Answer 1:  Ovals come in a zillion different shapes so, there isn’t one oval that will fit every design.  A pair of 1/2 round pliers and a pair of round nose pliers will shape a bezel.  You use the curved side of the plier on the interior of the bezel and use the 1/2 rounds to shape tight curves.  You can also use a ring mandrel, the post of a dapping punch, a broom handle (cut off) – basically anything that is rounded. The bezel is then pushed around the stone and given its final shape..  It is often annealed, during this process,  so that it is easier to bend.

 Have you made your own bezels?  If you make your own, you can shape them to anything.  After shaping and then soldering the edges of my bezel strip together, I use a steel burnisher to push the bezel against the widest part of the stone – that shapes one side of the bezel.  Then you flip the stone over so that the flat part, widest edge – is on the other edge of the bezel.  Burnish again.  This will give you an oval that matches your stone.

I don’t understand what you are talking about regarding a bezel for resin.  A photo might help.  What is a soft bezel?  Again, a photo might help.  I have a feeling you aren’t talking about a traditional bezel.  I don’t understand this either: “The metal is too thick to pass a cabochon through it”.
The thickness of a bezel’s walls should not affect getting the stone into it – unless the bezel was made too small for the stone or was soldered to the back plate at an angle.  I guess, because I don’t know what kind of bezel you are talking about, I’ll stop here.

Answer 2:  How do you fill an open backed bezel with resin?  Do you line it with something?  Have you seen the oval molds?  I’m assuming you have.  Your picture was pretty large and very blurry so, I’m going to be guessing at what I am seeing.

resin-mold
I think that the methods I discussed in the prior email would work – as they do for traditional oval/round bezel setting.  If you already had the oval cabochon, you could shape the bezel strip around that but, you aren’t making a cab, just filling a bezel with resin, right?  (You are reading my thought processes, as they occur! Just thinking this through).
 What about shaping it around a copper stamping?  18g-copper-oval  You could solder 5- 10 together and make your own mini-mandrel for 30mmX40mm.  Here’s an Etsy store that sells them. You could solder a rod to the back, or drill through and insert a bolt, to the center to hold in a vise or ring clamp – the bolt could also hold the layers together. IF you do this, use a drill press so that they are all aligned.  I’d glue them together with superglue before drilling too.  I like this idea and think I will make one or two!
making-oval-mandrel
 You could also purchase a 40mm piece of pvc or acrylic rod and shape it into an oval.  When the plastic gets soft, you can insert a slightly smaller oval of metal, into the opening and then let it cool.  You’ll have to deduct the thickness of the tube to come up with the right sized insert.  Ventilate VERY well when doing this.  Wear gloves. I don’t know if this will work.  But, it could. Maybe call tap plastics and see if they can make oval tubing?
 The next idea is to use a 40mm X 30mm stone and shape your metal around it.  Solder it, reshape, then do your resin thing.  You could also see if a woodworker can turn you a piece of hardwood into the shape you want. Or a metal worker doing the same thing.
I searched for two hours for anything 40mm X 30mm:  metal rod, plastic rod, metal tube, plastic tube, wood rod/tube, drawer pulls, anything oval.  I give up!  The closest to what you want is a hoop mandrel but, it’s round.
What I’d do is shape the metal around the cab or do the stacked stamping thing.  The PVC thing might be too iffy but, I don’t know, I haven’t tried it.  All I know, is that when I make oval cabochons, I make them around the stone.  If, the image you sent me, has a rim around it, you could always solder on a round or 1/2 round wire to the top of it.  The next best idea is to use the 1/2 round pliers.  You could try using an oval template or an oval stone, trace it and cut it out of some really thick stock. This link is for aluminum (much cheaper than brass or bronze and easier to cut than steel).  This link is for metal that is about  a 2 gauge.
There’s also this, heavy brass oval,  from Metalliferous but, they don’t state length and width. Maybe contact them.
Okay!  I’m out of ideas.  Obviously, what you want does not exist, as far as you or I can see.