Bronze Chess Piece

I’m terrible at gift giving (I often forget about social events like birthdays which creates many interpersonal issues), but when I do, I tend to try and think about something that has a connection to someone’s past. My business partner lost his mother to cancer some years ago, but she was an artist and through her creations, she left behind various pieces to remember her by. One of those items was a chess set, carved from soap stone. My business partner shared a picture of the set with me one day and I couldn’t help but see an opportunity to make him a Christmas gift.

Getting Started

I asked if there was any way I could get my hands on one of his mother’s chess pieces and he said yes but if I broke it, he’d kill me. I took the piece to a local shop and had it 3D scanned. You never know what kind of quality you’re going to get with 3D scanning techniques because different materials can create adverse effects in the output. Fortunately, the scan turned out great and the SLS print was more than adequate for my needs.

The Foundry

A couple of years back I made a makeshift foundry out of a cheap steel trashcan, some concrete, pipe and a blower motor. The foundry runs off of charcoal fuel (I’ve since upgraded to a propane-based foundry) so it needs constant attention to maintain temperature. In any event, I initially used it to create metal ingots that I can use for any of my other projects. If you’re interested in doing this yourself, there are a number of instructional videos on YouTube detailing how to make one (I take no responsibility and you’re on your own).

It takes about 25 minutes to get the foundry up to temperature at which point the pre placed brass pieces inside the crucible begin to liquify. It takes an additional hour to get a full crucible worth of liquid brass. During that time, I built the form of clay around the 3D printed figurine which would act as the mold. This is by far the most important step in the process, as the quality of the packing will dictate the resolution of the casting. I was far from perfect in this case and if I was to do it over again, I would be more careful about the packing of the clay and the vent channels for the vapors to escape. Long story short, it takes a bit of trial and error to get right.

As you can see in the video, the pour went pretty well, but I didn’t put in enough vent lines so there’s a significant amount of vapor bubbling towards the end of the pour that significantly affected the base.

Result

It took a couple of hours for the brass to fully cool, but once it did, I dumped the mold over and started brushing the clay off. I wasn’t expecting much of an outcome at this point, but I was pleasantly surprised with what came out of the form. After some cleaning, cutting and grinding, the figurine was at a respectable place.

I’m going to start doing more foundry related projects throughout 2019, so I suspect these posts will expand in detail and complexity.