Does anyone have instructions or advice for me as to how to set a 10x14mm oval cabachon into a 4 prong setting. More specifically on how to make the seats. I think I need a tool like a cup bur, but something that grinds on the outside surface, not the inside of the cup. I've searched the Internet and my reference books and have not been able to find any info. However, I have seen rings like this, so I know it can be done.

 Cabs aren't usually set in prong settings, cabs usually go in bezel settings and facetted stones go into the prong settings.  That being said...you need a bur that can cut the seat in the prongs, a cup bur is not the tool to use, it's used to round up the ends of wire or you can make a ball perfectly round with a cup bur. 

You can cut the seat with a hart but or you even use needle files.  I would suggest getting a stone setting book or check out Oppi Untrect (spelling - I often spell that last name wrong), books at your library.  Perhaps even YouTube???  I offer that cutting seats for prong settings is not a beginner's project.

Hello Loopy, Thanks for your comments. I do have the book Creative Stonesetting by John Cogswell. He does not address this setting. I have had Oppi's book on backorder from Amazon since last October. I will admit that I have little experience, but I do have a one year degree in jewelry repair & fabrication and have taken a semester of stonesetting, so I have cut seats for faceted stones in 4 prong settings. I was just wondering if there was a bur that was shaped like a cup bur, but had the cutting edges on the outside, so as to cut an upside down half round seat for the cabachon. Lynn www.lynnwhitejewelry.com

Lynn M W:

I was just wondering if there was a bur that was shaped like a cup bur, but had the cutting edges on the outside, so as to cut an upside down half round seat for the cabachon. Lynn www.lynnwhitejewelry.com

I can't really visualize what you are looking for, but if I have it right, you could probably make your own. Grind the tip off a setting bur. Then, using a smaller ball bur, grind in the "cup". That will leave you a smooth interior with the cutting edge on the outside.

Just a thought.

Betsy

The seat for a stone can be cut into prongs by a variety of applications. Although the most common use is a setting bur or hart bur for a round setting, placing an oval stone into a four prong head or crown frequently eliminates this possibility. In this scenario the individual seats are cut into each prong with a combination of hand tools; generally saw frame, files, and gravers.

Although production stone setting often relies on use of a flexible shaft or pendulum drill and rotary cutting tools, the most reliable and controlled method is removing the metal by hand with simple tools. This approach provides more precise control of the outcome as well as allowing less opportunity for damage to the setting or the stone, or for injury to the setter from a momentary loss of control of a rapidly spinning tool.

There was an earlier comment on this thread about prongs being used for faceted stones and bezels being used for cabochon stones. This could be the perception of limited exposure to jewelry, or contact with examples which are  primarily commercial jewelry or that which relies upon assembly of commercially produced findings. In the larger realm of jewelry design there is no such categorical limitation in the use of settings. Many jewelry artists fabricate prong style settings for cabochons and set faceted stones in bezels. To the skilled jewelry maker/designer/goldsmith any combination is possible.

Stone setting is a very specialized part of jewelry making. One can endeavor to teach one's self but in my experience they will very likely adopt bad habits and develop incorrect approach in addition to investing much time and energy with poor results.  The best way to learn stone setting is by taking a workshop or classes with an expert. The money invested is well worthwhile if this is something which will be a major part of one's body of work and will necessitate proficiency and reliability.

 

Can you give more information about the setting? I guess I"m not sure why you need to 'cut a seat'. Is there no backing on the setting? Is there no wire seat? I have put cabs on pieces using prongs but didn't cut a seat I simply filed the prongs and then pushed them over. I'm not sure what you're trying to do really, BUT, having said that, I'd just cut a seat with a setting bur, straight down each prong to the depth I wanted, then drop the cab in and push the prongs over.

Hi All, I have decided to use a round bur with its bottom half ground off to cut the seats. The setting is Stuller 1902-64898:S 14KY. Wish me luck. Lynn

Good solution.

So you're using a pre-fab setting?

Yes.

I'm with Wireywoman: for a cab I'd just cut the prongs down to a manageable size and fold over the stone.  As long as the stone has something to sit on you should be fine unless you're trying to "suspend" the cab in a prong setting - in which case I'd go with what you've already decided.

Let us know how it works out!