I’ve been working on using 3D prints to create aluminum castings. I did my first test today and it worked.
I unfortunately don’t have a pic of the print. It was just a failed print of a ram cooler I designed. Anyways, I submerged the print into plaster of paris. Let it cure for a few days, then placed the print and plaster into my kiln and heated it to 700F-800F. This melted out the 3d print and left a void in the plaster of paris mold. I should have gotten to 1,000F, but I had to cut it short.
The next day, I melted aluminum in the kiln and preheated the now cold mold in my powder coating oven to 500F. Poured the aluminum in and this came out (last 2 pics).
I did have some cracking in the mold. I’m not sure if that is because I had to let it cool down, or I heated it too fast. So there is still some testing that needs to be done. Next I have a model of the Prometheus from Stargate SG1 off of thingiverse. I’m printing it now, so we’ll see how we’ll that works.
Try to add a vent away from where the aluminum is poured in. Also look at wall thickness. Remember metal doesn’t like thick then thin then back to thick.
@Georg_Mill An electric kiln for pottery. The one I have can get up to 2,200F or 1477.44 kelvin. I won’t be able to do copper or brass with it, but it works great for aluminum.
I’ve used a 50/50 mix of sand and plaster of paris, cured for a couple of hours, burned it out on the charcoal grill, and poured right into the hot mold - no cracking. I don’t know if it is the extreme preheat or the sand…
Did this same thing in my furnace, but didn’t pay attention to the temp: I literally melted the plaster into a glowing glob on the bottom. It does not smell good when melted :S Live and learn eh?
@Alan_Thomason : Why the 50/50 mix: I actually have done the same thing, but for on reason other than that’s how I heard others do it. Are you actually aware of some sort of advantage?
@Alan_Thomason@Eric_Pavey Thanks. I have a feeling that it is best not to get the plaster of paris past 500F-600F. I believe at around that temp (hard to remember, I should write this stuff down ) the pla started to burn off/vaporize. I also didn’t see any more cracking as I poured the aluminum in. So thermal shock may not be as big of an issue as I originally thought. On the next one, I’ll only perform burnout up to 600F to see if it cracks. And I’ll make sure to document temps a little better. One of the great things with the kiln. Fine temperature control. LOL
@Alan_Thomason Just an FYI. I’m not sure if you know this. From what I have read, if you heat up plaster of paris past, I think 300F, it is reusable. Since you are melting out 3d prints, you could probably just smash the old mold back up and re use it.
@610GARAGE I had absolutely no temperature control on the charcoal - plaster/sand mold was glowing a very dull red; but, I have no idea of actual temerature. I would like to hear of your results.
What? I hate math. LOL 