I've now done a few more test casts and have range of methods that don't really work.
Plaster Of Paris using Lost-PLA Casting (Melt Out)
: Tried a few more (both surface and full molds) and the results were mixed. I was using eSun PLA+ so no idea what is in it but it does not burn out cleanly, and as a result the detail can be poor. The surface mold was better at burning out as you could then (carefully) brush out what is left.
Verdict: Not really a great method, but could be fine if there was a better filament to use for burning out. So....I did get my hands on some wax filament that would be perfect but I've been unable to get it to feed though my drive gear + from what I've read, you also need to mod the firmware to let the Prusa print at 80c . It would be interesting to see how this would work if I could get it going as wax melt out is a real method.... if only I could work out how to print with it. I was also thinking about some of the soluble filaments but Plaster is water soluble as well so that is out (and who knows what Limonene would do if trying HIPS).
Direct Casting into 3D Printed Negative :
From what I've found you can cast directly into a 3D Printed mold (see pic of Frog) but:
- Needs to be ABS (not ABS+) as it does not stick to the pewter
- Works best on small items where the Pewter has time to freeze before the ABS deforms to much (but you will lose detail)
- Needs 10 Perimeters (had a blow out testing with just 5 on Buddy2 - see Pic)
- If it is a full mold (not just a surface cast), dissolving that amount of ABS takes days
- Works better if you dust the inside of the molds with some Graphite as a release agent, it helps stop the formation of bubbles on the pewter surface
Verdict: It would be OK for casting small items especially if it is a flat one sided item so you can just pick the pewter out of the mold with the advantage that it is quick and easy to print such molds.
Caulking High Temp Silicon
: Give this one a wide berth. There is a reason there is silicon mold material you can buy and trying to make one using the stuff from the Hardware Store (for sealing ovens etc) is just not a good idea. I could not release the 3D Part from my mix so did not even get to the pouring metal.
Verdict: Bad Bad Idea
Smooth On Mold Max 60 Silicon using 3D (Printed Positive)
: TBA, the silicon just arrived today but the pump that came with the vacuum chamber kit I bought is rubbish, so I'm waiting for a replacement (this stuff is expense and you don't get much so I want to give it my best shot).
Green Sand Casting (Printed Positive)
: TBA - yet to try but this of course should work (as that is the normal way of doing things, + you can cast higer temp metals.