Well, it took long enough, but my miniature foundry is finally up and running. What this means is that I am finally able to turn digital models into metal objects using a combination of 3D printing and investment casting.
There are means to fabricate metal objects via 3D printing directly, such as my personal favourite process, selective laser sintering (SLS). However, metal 3D printing equipment is a bit beyond my budget at the moment, so I’m using a much more conventional process, which is to print patterns in castable wax resin and make moulds from them. As I’m typing this, I’m taking a break from working on these moulds to make my monthly updates. I’m working on three more videos that document the entire process of printing, mould preparation, and casting. Complete post-processing of the metal castings will also be included in the event that I like the way the castings come out. For those of you who enjoy seeing this type of work, I recommend that you follow me on Hive if you haven’t already. I have shared some more extensive documentation of the setup process and first casting runs there. To make a long story short, however, I have made some wax part trees and tested out one of them using tin.
This first casting run didn’t come out the way I would have liked, as I failed to free the trapped air bubbles inside the cups, despite my efforts. There were also plenty of little bubbles left in the mould itself, which means that the investment wasn’t thoroughly de-gassed. Next run, I’ll leave it in my improvised vacuum chamber (a bucket attached to a pump) for longer, and see what happens. Below is an example of the casting quality that I’m currently getting.
Bear in mind that this cup, cast in lead-free crown pewter, is only 12,7 millimetres in diameter (0,5 inch) at the rim, and 18,3 millimetres tall. I have printed several models of varying complexity in castable wax resin, and I’ll use the simplest of them (such as a mushroom that I found on Thingiverse many years ago) to test and perfect my process before moving on to higher temperature casting. Currently, there is a part tree of three rings prepared, which I intend to cast in bronze:
These rings are all the same size, which I don’t know off the top of my head because my ring size chart is in my machinist’s toolbox. These are pinky rings for me, incidentally. On a somewhat humourous side note, I turned a fake wedding band out of 316L stainless steel, using the lathe in my home shop, and wore it when I was in college – I was there to study, not date, because I’m boring.
Currently, the scale I’m able to work with is quite small. The cups, for instance, should have been horizontally opposed, but there was simply no room in the flask for that, hence the orientation that I actually used. I can’t use a bigger flask, because the burnout kiln I have is tiny (and non-programmable). However, I can melt up to 4 kilograms (8 pounds, 13 ounces) of bronze in my crucible furnace, which can make some rather substantially-sized objects – such as components for model steam engines. Oh, the possibilities!