3D Print Result

I have succeeded in producing a fairly good cast ring from a 3D print master model. This came after many failed and unsatisfactory attempts. There have been numerous issues but the hardest one to overcome has been the failure of the investment during the model burnout. The resin from the model apparently doesn't totally cure. Especially in a thick section model. The uncured resin combines with or attacks the gypsum in the investment during the investment cure and subsequent burn-out.

I found a written article published over two years ago that confirmed every one of my suspicions. A jeweler in Bellingham, Washington, Jim Binnion (https://mokume-gane.com/about/jim-binnion/) offered a solution. It involves high vacuum curing the model in a heated oven, after ultrasonically cleaning it in water, fresh off the printer. No alcohol is used on the model and a UV cure isn't necessary either. 

Jim is a professional jeweler and has professional grade equipment. I assembled a hobbyist grade equivalent, seen in the following pictures. I can't get or measure the 10 micron vacuum Jim recommends. I did notice the vacuum stop at one level, then about an hour later it dropped anotherl .5 inch WC. An indication there was gassing off of the tiny model, which created the drop in negative chamber pressure. I was heating the chamber to 180 degrees Fahrenheit. There was also some condensation (resin?) on the clear and cool lid of the chamber during the vacuum operation.

This ring is one of my best 3D printed casts so far. So, it looks like Jim's information about using a vacuum was good and I am on the right track to good casting. I will continue using this method. I have also resigned myself to keep the model section as thin as possible. The thicker the model the harder it is to properly cure.

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This is the ultrasonic cleaner I use to clean the model and many other things. After the cleaning, the model is placed in this heated chamber and a vacuum is pulled. I let it run about 2 hours.
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This is the ring after it came out of the vacuum chamber. The sprue is wax. I also touched up a few blemishes on the ring using repair wax and a heated, wax pen.
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The results after kiln firing and casting The ring following the usual after-casting clean up process and shining.
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The ring is quite small. I call it Pave' less the Pave' 3D printing does work when you learn the trade secrets. It is not an easy process.