I had a couple of matching wedding rings to make and usually , like most people in the cad game (and handmade game) I use the paper and pencil trace on a mandrel. This method however leaves much to be desired because it does not take into account any slope in the rings head, hollows or undercuts, and is subject to distortion when being re-wrapped and is really only useful if the ring has a subtle curvatures.
The solution has been under my nose all this time.
My MDX-15, which is a capable entry level mill, but is also configurable as a 3d scanner. So, I tried the scan option method.
I set the XY pitch resolution to 0.2mm as I only need a basic shape not a detailed copy, so it took an hour to scan both rings as a single operation, I then imported the mesh to Rhino , projected a circle against it to create my "follow" curve and got perfect fit matching wedders at around 5 minutes design time each.
I can kick myself thinking about all the time I have wasted in the past with post casting issues, scaling and with having to try fit these things properly by hand.
The scan method allows me to accurately place my designed wedder against the "ring" it is intended for and make alterations as required at cad level. These jobs are unfortunately not for myself so I wont see them again, but I am willing to bet my bottom dollar they will fit EXACTLY.
I think I am going to get a little more use from my MDX-15.
Images follow logically.