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justin1287

How In The World Do I Make This?

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justin1287    1

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.

post-16111-0-07169500-1400368587_thumb.jpg

post-16111-0-07169500-1400368587_thumb.jpg

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JBaymore    1,432

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

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jrgpots    231

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

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Pres    896

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.

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TJR    359

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.

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Mart    23

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).

 

post-19541-0-06053900-1400487772_thumb.jpg

 

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.

post-19541-0-06053900-1400487772_thumb.jpg

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