3D-Printed molds for casting metal objects, first try

Creating metal objects is rather simple if you already have a cheap FDM 3d-printer. Just print it in PLA, put into gypsum, dry it, burn out the plastic, pour in the metal… PROFIT. Looks simple, right? Well, I decided to give it a try and here’s the very first sloppy result. More details about the experiment below.

I started by printing the witcher medallion I grabbed from thingiverse. Here’s a link:

The shape was small enough and had just the right amount of fine detail to be challenging for my homebrew tech. For instance, Slic3r failed to privide sufficient support for the top pair of teeth, so the wolf ended up a little bit messy.

Next step was putting it in gypsum and leaving to dry for a week or so.

Once I got back I burned out the plastic and poured some metal. I used soldering leftovers that I’ve collected over the last decade or so, so the temperature was not that high 😉

The only remaining thing was to cool it down and break gypsum.

Looks okay for the very first attempt. A few lessons learned:

  • Good gypsum dries VERY fast. You have just bare minutes to mix everything and put the plastic in it. I only managed to do it the second try
  • Burning out plastic with a gas torch was a bad idea. Temperature was not enough to burn out PLA completely and due to the temperature shock the gypsum cracked in different places.
  • Leaving a ‘bottleneck’ at the top is a good idea, the more pressure – the better the detail
  • I really need to think about a better surface finish. Sand polishing?

All in all this was a very fun experiment. I should do it again pretty much soon and improve some things here and there.

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