In response to our post about 3D printing spec parts from the design files in McMaster-Carr’s online catalog, reader Frankie Flood pointed us to his posts about sand casting 3D printed parts. This first piece posted to his blog was his first attempt at documenting casting of the 3D printed parts. The post is almost entirely photos, but here’s how he describes how the casting came about:
You have to love McMaster-Carr. They’re kind enough to post CAD files of their hardware. This makes life easier when I need a wingnut in a hurry or if they don’t have the size I need. This happened this past week, so I downloaded their file, scaled the model to the size I needed, printed it out on the ZCorp 3D printer, made a sand mold of the print, cast it in bronze, cut off the sprue, sandblasted, drilled and tapped on the lathe, polished, and then installed it. Not quite as simple as placing an order, but they didn’t have what I wanted anyway.
Later, when he needed more of his custom-sized wing nuts, he created a larger photo gallery of the casting process. Again, it’s mainly wordless, but the images speak for themselves. Here’s what he says about his flasks (the molds used in metal casting) and the casting sand he used:
I’m using some homemade flasks that I made on my South Bend lathe, but I’ve shown my commercial cast iron cope and drag flask. My flask just has a small lip that fits inside the other half so they fit together nicely. I have created an indexing mark as well so I can make sure the two halves are aligned when I take my pattern out and put the flasks back together. These could be built out of almost anything. I’m using delft clay/sand from Rio Grande. You could also use Petrobond and some people make this themselves. My only advice is make sure to separate the charred sand from the good sand after you pull your finished cast piece out of the mold. Throw the charred stuff out as it will ruin your sand if you mix it in with the good sand.