Tricks and Tips for Designing in CAD

As you see more and more of Brandy’s CAD (computer aided) designs in my shop, I thought it might be time to explain the design aspect of the process a bit more.  This will also help you if you are interested in placing a custom design order that requires CAD.
When do you need CAD?  CAD is extremely useful when you don’t want to make a design from scratch in metal, and especially when you have an idea that is more complicated, like my halo and multi-stone rings.  Imagine how long might take to make all those tiny little prong settings, for instance.  CAD is also useful when you have a specific stone and can’t find any stock settings that work.  But CAD doesn’t work well for flowy designs, and the geometry for certain shapes is incredibly complicated.  The more curves, ridges, settings, the more detail in other words, the longer it takes. 
Wedding Band CAD with Dimensions
A CAD ring will indeed take several hours in design work, or even more.  A simple setting might only be 30 minutes, but if you’re designing a complicated gallery for instance, adding all those curves and finalizing the dimensions can take an afternoon.  After that, the CAD model has to be “printed” in plastic , then cast in base metal, then molded, then again cast in the desired metal.  You can also go straight to casting from your plastic model, but if you then need another one, you have to print again, and printing can cost up to $100.  3D printers are expensive, and the printing process is slow.  Long story short, you are looking at a few hundred dollars before you so much as have a first casting.
Since CAD works on a mathematical basis, you need all your dimensions pretty well worked out before you can begin, and you may need to refine them as you design, or go back and forth with your CAD person.  This includes inside diameters of bezels, thickness of bezel walls, prongs, etc, for each part of your ring.  Brandy, who is very good at this, often supplies these after I give her the stone, or stone dimensions, the basic ring dimensions and my drawings.  She knows how deep a setting has to be to fit a stone, what wall thickness is required for a bezel, how much space to leave between stones, and other things you’d never think of if you haven’t done this a lot.  Nevertheless, sometimes Brandy and I have to sit together for a couple of hours and hash out specs as we try them out on the screen. 
This Cluster Ring is not Done Because We're Working on the Gallery , Often the Hardest Part
You also need to have a good sense of imagination, because a lot of time a model looks one way on the computer, another way when it is printed and cast.  One of my new rings ended up too heavy on the top, and the shanks were too thin to make it look balanced.  And when you plan to add stones in a beaded or burnished setting, you need to be able to visualize how the piece will look when it’s finished, because on the screen, and even in the silver casting, it will just be an empty canvas.
My Victorian Flower Earrings Before Setting

A Finished Design with the Same Setting
Sometimes other impracticalities intrude that you don’t think of.  Your finger is too small to support several stones in a row, or sizing will be an issue later.  Eternity bands have to be done for each size for instance, and in each case you have to change the design a little.  You also can’t just make a design bigger or smaller because you will want to shrink just certain aspects (i.e. the center setting but not the shank).  This means that certain changes in size necessitate many other changes down the line. 

               Finally, you have to think about practical aspects during casting and printing.  The ring I made (below) cannot be cast in one piece because the silicone could not get underneath the ring.  So Brandy made a gallery, lifted the top and made two designs that have to be assembled after casting.  Also, since you can’t cast in two metals at once, any two tone designs require two models that have to be fitted together and assembled.  
Shank is Too Narrow (The Thing on the Right is the Sprue)

Can't Mold in One Piece

Top is Too Thick, Needs a Galllery