Last month, I prepared a batch of small 3D-printed objects for the “lost ABS” process, some to be cast in aluminum and the rest in bronze. One of the pieces, a 3D-printed two-part mold, was placed in the kiln on Tuesday and cast with aluminum on Thursday. The other three pieces were all supershapes I had generated in OpenSCAD and 3D-printed in ABS earlier in the semester. I thought they would look great in bronze, so they were loaded into the kiln on Thursday and poured on Saturday morning. This post is all about the creation of those bronze supershapes, along with a cast aluminum cradle I created to present them.
Printing and preparing the original forms
Using a helpful OpenSCAD script, I generated a batch of supershapes and printed them out using UNK’s new Makerbot Replicator using ABS plastic. I then prepared the forms for the lost ABS process at UNK’s sculpture and glassblowing studio. I have much more documentation of this process, including the gating and casting of these shapes, at the following link.
More photos from this process can also be found on Flickr
Pouring the bronze
After being yanked from the kiln and set into a pit of sand, my three molds were filled with molten bronze and left to cool for a couple hours. The sculpture professor, Chad Fonfara, had me step into the dead-lift position and help pour the molds, which is a pretty awesome experience to say the least.
Demolding, cleaning and finishing
Once the bronze is poured into the molds, they are left to cool for a couple hours, at least until they are able to be handled with gloves. The plaster molds are broken open using a claw hammer and some wire cutters, revealing the raw bronze forms. Chisels and wire brushes are used to gently remove any remaining plaster stuck on the objects.
Once cleaned of plaster, the gating system is roughly cut off using an angle grinder, then finely worked away with rotary tools. The real challenge at this point was to remove the gating system while preserving as much of the detail as possible. The grain of the 3D-printed filament lines was really interesting, so the more of that I could keep the better.
Each model had a single shrink hole at the location of the main input gate, telling me that air was not able to escape fast enough during the pour. More gates would be smart next time. The holes were filled using welding equipment, then worked back into the model.
Each piece was sandblasted and worked with steel wool to get a nice shiny appearance. A patina was applied, followed by a brush coat of wax to preserve it all.
Cast aluminum cradle from carved lost foam
To present my bronze supershapes in an aesthetically interesting way, I carved this cradle out of foam and cast it in aluminum using investment casting. It took quite a bit of work to clean up the form and polish it to the finish that I wanted using an angle grinder, but it was completely worth it! Since this part of the piece was more of an accessory, I won’t go into all the gory details. But here are all of the photos I took of the process: