Haus
I am Big Balls!
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Well, the first test was an absolute fail. The oven I have isn't hot enough to really liquify the PLA to extract it, so I had to go with the "burn it out using the molten metal you pour in" method, which isn't optimal by far (see the red eyed skull above for what that process yielded). Don't know if I'll keep this around for my "Gallery of failures" , I mean it's still an all copper skull weighing in at around 3lb 7oz.
I think the reason for the fail was in part due to the melting plastic popping and "exploding" minimally which broke up the inner plaster part of the mold. Modifying to try again, minimizing plastic in the print (print with a single shell wall , i.e. "vase mode") and print the feeder tube so there's a block to keep the metal from free falling into the mold...
The bigger tube will be the downpour feeder for metal, the slim tube will be the vent for gasses escaping the mold cavity.
I might also use a method not doing the "complete encase in plaster" stuff. And instead use "artificial sandstone". That's where I do the base layers of plaster around the mold, but then instead of putting it in a flask and filling it with plaster like I did this time, I just put the shell in a container and pack around it with sand mixed with Sodium SIlicate (aka waterglass). That works a lot like greensand for casting, except that as the sodium silicate catalyzes with air it becomes silicate and turns the sand into essentially sandstone.
For reference : this is what the filled plaster flasks looked like :
The taller flask I still haven't poured. Will probably pour that one tonight, and use a lower temp metal like aluminum rather than copper/brass.
I think the reason for the fail was in part due to the melting plastic popping and "exploding" minimally which broke up the inner plaster part of the mold. Modifying to try again, minimizing plastic in the print (print with a single shell wall , i.e. "vase mode") and print the feeder tube so there's a block to keep the metal from free falling into the mold...
The bigger tube will be the downpour feeder for metal, the slim tube will be the vent for gasses escaping the mold cavity.
I might also use a method not doing the "complete encase in plaster" stuff. And instead use "artificial sandstone". That's where I do the base layers of plaster around the mold, but then instead of putting it in a flask and filling it with plaster like I did this time, I just put the shell in a container and pack around it with sand mixed with Sodium SIlicate (aka waterglass). That works a lot like greensand for casting, except that as the sodium silicate catalyzes with air it becomes silicate and turns the sand into essentially sandstone.
For reference : this is what the filled plaster flasks looked like :
The taller flask I still haven't poured. Will probably pour that one tonight, and use a lower temp metal like aluminum rather than copper/brass.