Jan 28, 2016 | By Alec

Though 3D printing is inherently a very modern making technology, various artists have been showing the world that it can also breathe new life into techniques like ceramic modeling and glass casting – which have been around for centuries. The results are often spectacular and artisanal. This can also be seen in most recent project by 3D printing guru and performing veteran the Great Fredini, who has created some spectacular glass figures – the result of a combination of glass casting and 3D printed PLA molds.

If the name of the Great Fredini sounds familiar, that’s probably because he has been behind some very experimental 3D printing projects over the last few years. Remember the world's largest 3D printed installation in Coney Island? His real name is Fred Kahl, and he is a Brooklyn-based artist with a long performing history at Coney Island who discovered his making passion a few years ago. He spent much of 2015 in a flexible fellowship at Wheaton Arts’ Creative Glass Center of America, where he was working on combining glass casting with CAD-made sculptural forms. “I worked extensively with glass many years ago but now create most of my art with 3D scanning and printing,” he explains.

And the results are pretty impressive. As he explains, he decided to explore a number of casting techniques with the help of 3D printing, leading to some interesting discoveries. “I usually begin with 3D scanning, primarily structured light scanning with Primesense/Kinect style devices and occasionally photogrammetry for non human subjects. Other non-organic forms are just modeled directly in the computer using my software of choice Zbrush,” he says of his design process. These designs are finally 3D printed, but this time around the 3D print wasn’t the last step of the process.

In fact, he started out with a technique called lost PLA kiln casting, which is basically a 3D printing version of wax casting. The wax/plastic model is covered in plaster, heated to remove the material and leaving a quality mold that can be filled with glass, metal or whatever other material you fancy. Starting out with a PLA 3D printed positive, he first covered this with a plaster/silicon mold. “I began by plugging any holes in the surface of the 3D prints with microcrystalline wax and waxing the prints down to a table,” The Great Fredini explains. “I mixed a small initial coat of mix with no fiberglass strand to use as a splash coat over the object, then mixed subsequent buckets of mix to fill the molds completely.”

After at least a day of drying, the resultant molds were loaded into the oven to start heating, but Fred quickly discovered this process wasn’t as easy when working with PLA. Wax is generally just steamed out quite quickly, but PLA proved more difficult to shift. “Even though PLA is a biodegradable corn starch, the burnout is smoky and not good to be around so it had to be timed to happen overnight when the studio was empty. I would begin by soaking the oven at 300˚ for about three hours and then pushing it upwards at about 100˚/hour,” he says of the difficult process. “At about 450˚ I would go in (wearing gloves, glasses and a respirator) and use pliers to pull out some big chunks of plastic as it started melting. I had to be careful not to damage the mold in doing so. At about 700˚, I would go in with a stainless steel turkey baster and suck out as much molten plastic as possible.” The smell was terrible. Incidentally, a more useful product exists (Moldlay filament by Kai Parthy), but Fred wouldn’t discover that until later.

But it did work – Fred did end up with plaster molds. These were then filled with molten glass, for which he tried two techniques. The first is what he calls ‘Lacrosse Casting’, and involves standard furnace glass passed around from one ladle to another, to remove all bubbles. “I would gather a ladle of glass, then dump the ladle into a second ladle someone else was holding. They would rock the ladle side to side so that the molten glass skinned up on the outside a little. They would then dump that back into my ladle and I would go to the oven and gingerly drop this “hot tamale” of glass into the mold,” he explains. Unfortunately, this very time-consuming technique was prone to damaging the molds, though some results turned out pretty good.

Fred therefore moved onto the second technique, which revolved around using some crystal glass – more expensive, but resulting in far better and clearer casts. “After the mold is burned out, I would let the oven slowly return to room temperature so I could carefully vacuum it out and pack it with chunks of glass,” he explains. “The small chunks could then be loaded in the mold, and the oven slowly brought back up to about 1550˚ until they melted in completely and the worst of the bubbles came to the surface. At that point the oven was crashed back down to under 1000˚.” This definitely proved to be the best technique for Lost PLA casting, and the results look amazing. Unfortunately, the crystal glass makes the whole project quite costly.

With crystal glass.

It definitely proves that lost PLA casting can be used to cast custom glass creations, though the results would be far better when using Moldlay filament. Incidentally, Fred further tested CNC-carved graphite molds, which were reusable and thus more cost-effective, but obviously less cool. “Lost PLA castings also required extensive work divesting from the mold, then grinding and polishing. I had long wanted to experiment with CNC carving as opposed to 3D printing,” he explains. The graphite molds can be seen below. However, one thing is crystal clear: modern computing and making techniques can definitely add a whole new dimension to traditional artisanal manufacturing.



Posted in 3D Printing Application



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