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This type of shell enables holding the mold together with paper clamps, making for easy removal when plaster is set. Here is the simplest way to draw it.
-Draw the jigger mold profile like shown below left (we use a 0.8 thickness outline).
-Draw another 6-8 mm outside it, that will be the flange.
-Revolve the mold profile 359.5 degrees, leaving a small gap, perhaps 0.5mm.
-Rotate the flange (with join operation) 0.5 degrees (hopefully producing 1mm thick, adjust as needed).
-Rotate the flange again (with join), but in two sides of -1.0 and 0.5 degrees (creating the other flange).
Notice the details that enable printing this upside down without generating any printed support. The printed PLA is left on the plaster mold above and below the shoulder, enabling precise fitting and good wearability.
Turn this upside down and center it over a plaster or 3D printed form of the outside shape of a mug. This creates a mold that drops down in our Shimpo cuphead. This opens slightly along one side for easy release from the plaster after set. It is held together by paper clamps during use. The upper flange can be glued down to a smooth surface with a clay slurry. If you would like this 3D file in Fusion 360 format, it is available in the Files manager in your Insight-live.com account (click the link below to go straight there).
This is part of a project to create a new mold. I have to make various iterations to arrive at a final design where rubber will be used to make the case mold. But until then I will 3D print the case mold directly. Here are some features that make this super cool:
-The center section is the jug being cast (two pour spouts will be glued on). It is hollow and will be split horizontally in the slicer so the two halves can be printed with open side up and then glued together (with the aid of printed inner hoops to align them).
-The mold seams, where the two halves mate, is printed as a 0.4mm membrane connected to the model and running vertically down its center.
-The membrane has 9.4mm holes for the insertion of standard mold natch pairs. During plaster pour the membrane will flex somewhat, this will be a benefit to aligning the halves.
-The outer shell halves have no angles steeper than 45 degrees and thus print without printed supports. The flanges were drawn using our rotation technique (see link below).
-The round flat base will be glued onto the bottom disk.
-Any rough surface sections of the model (printed on top of support), will be coated with a fluid epoxy to smooth them.
-A separate handle mold will be made.
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