justin1287 Posted May 17, 2014 Report Share Posted May 17, 2014 I 3d printed this object out, and am trying to make 2 a piece mold for it, but the plaster keeps sticking on the inside. The inside angle is a little over 3 degrees. I tried using oil to make it slippery, and even made a plaster mix with a higher water ratio than normal. Thanks. Link to comment Share on other sites More sharing options...
Guest JBaymore Posted May 17, 2014 Report Share Posted May 17, 2014 As plaster cures, when it gets hot , it expands a tiny amount. Are you letting it cool back off before trying to remove the core of that hollow piece? 3 degrees is not a lot of taper.... ..... also are you sure that the 3 d printer held that accuracy? best, ....................john Link to comment Share on other sites More sharing options...
jrgpots Posted May 18, 2014 Report Share Posted May 18, 2014 If you have an air compressor, you might be able to blow air into the crack between the plaster mold and the cup to break the suction. Jed Link to comment Share on other sites More sharing options...
schmism Posted May 18, 2014 Report Share Posted May 18, 2014 can you use release agents with plaster? (like pam non-stick spray) Link to comment Share on other sites More sharing options...
Pres Posted May 18, 2014 Report Share Posted May 18, 2014 Make it a 2 piece mold with the bottom separating from the wall. then you can work the piece out of the mold from top or bottom. Link to comment Share on other sites More sharing options...
TJR Posted May 18, 2014 Report Share Posted May 18, 2014 can you use release agents with plaster? (like pam non-stick spray) You can use Murphy's Oil soap. Comes in a spray bottle. I think you can get it at Home Depot. I bought mine at Canadian Tire. TJR. Link to comment Share on other sites More sharing options...
Mart Posted May 19, 2014 Report Share Posted May 19, 2014 Are you sure you do not need a 3 piece mould? (I can not tell form the picture, how your piece looks like) - 2 for sides and one for the bottom. If not, use 2 piece - one for the bottom. I mix olive oil with "household soap" (old school stuff still used to hand wash clothes on washing board. I have no idea how it's called in US.) aka mould release etc. The bottom part for your mould (blue). When the plaster gets hot and then starts to cool, it pushes lots of water out from the plaster. Sometimes (not always) this is the best time to open the mould. But it obviously depends what plaster mix is used, how big and what shape etc is the piece etc. I have left stuff sitting overnight and never had problems. Start with that. Link to comment Share on other sites More sharing options...
justin1287 Posted May 19, 2014 Author Report Share Posted May 19, 2014 Thanks for the ideas....will try some new ideas out when I have a chance to get back to that project! Link to comment Share on other sites More sharing options...
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