Cast an inline 4 engine block with plaster mold

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Xijian Su

Member
Joined
Feb 24, 2020
Messages
19
Reaction score
33
Location
Dayao county, Yunnan province, China
Hallo to all!
Recently, I started my first project. I tried to cast aluminum alloys with plaster mold.
  • Design the engine parts
1UQ}T~TKBMHQ{F)S{%O[44F.png

This is the engine block designed with SOLIDWORKS. It takes me a week to build the 3D model.
IY~J2OGNHW9OTV3$7`7U207.png

  • Design the mold for 3D printing
To make the plaster mold, I've got to make a Silicone rubber mold first. So I designed a mold for the silicone rubber mold making. Here's the picture.
BZJJS]R}VQXD%]%R11N@BZN.png

Then I bought a can of silicone rubber from the "Taobao" for the mold making.
IMG_20200225_032604.jpg

There're 3 mold for the plaster core and mold making.
IMG_20200225_032736.jpg
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  • Plaster mold making
The mixing ratio of water and plaster powder is 1:1.5.
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This is the mold that hardened. The I put it into my electric furnace.
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To prevent the plaster mold from cracking. I slowly raised the temperature. No faster than 150 'C / h.
Here's the curve of temperature I followed.
IMG_20200225_035830.jpg

After nearly a whole day later, the plaster mold finished. Then I poured the metal into the mold.
IMG_20200225_040136.jpg

After a few minutes, I break the mold.
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The casting has a fine surface.
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Looks very good to me!!! Someday I'll use my brass-bronze scrap to cast something, I have enough for sure!!
 
looks good - was the pattern 3D printed from the solidworks 3d plan
 
WOW! What an amazing result. Are the plans for your engine your own design?

I will be watching with great interest.

Cheers,
Andrew in Melbourne
 
Wow, I am surprised that heating the mould to that temperature worked. I would have expected the plaster of paris to revert to gypsum at about 100°C, and even more suprised that it sat at 730°C. But a very nice casting, Su.

Bill in Cardiff, Wales
 
really excellent casting.
Two questions
1 did you pour liquid metal into hot mold ?
2 did you used common plaster or some kind of casting plaster.
Thank you
 
The design appears to be of the Westbury Seal. Is it the 15cc version or the 30 cc version?
 
@BillD
according to
https://en.wikipedia.org/wiki/Plaster_mold_casting
you can use special plaster molds up to 1200°C / 2200°F - Xijaan Su even gave the heating/timing curves for drying the mold AND using it immediately thereafter in post #3.
Aluminum can be cast safely with this plasters, as can be brass - the temperatures here are 900 to 940 °C / 1,650 to 1,720 °F.
Always use a well dried & preheated mold to avoid cracking.
 
To prevent the plaster mold from cracking. I slowly raised the temperature. No faster than 150 'C / h.
Here's the curve of temperature I followed.
View attachment 113992
After nearly a whole day later, the plaster mold finished. Then I poured the metal into the mold.
View attachment 113993
After a few minutes, I break the mold.
View attachment 113994
The casting has a fine surface.
View attachment 113995
View attachment 113996
View attachment 113997
View attachment 113998
View attachment 113999
View attachment 114000
Very impressive, well done.
 
@BillD
according to
https://en.wikipedia.org/wiki/Plaster_mold_casting
you can use special plaster molds up to 1200°C / 2200°F - Xijaan Su even gave the heating/timing curves for drying the mold AND using it immediately thereafter in post #3.
Aluminum can be cast safely with this plasters, as can be brass - the temperatures here are 900 to 940 °C / 1,650 to 1,720 °F.
Always use a well dried & preheated mold to avoid cracking.
Thank you!

Xijian Su
 

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