ok. for larger casts metal is
1- expensive and 2- heavy
For larger casts resin is
1- expensive and 2- fragile
For large flat sheets (buildings ect) both carry a risk of warping.
The Imperium does not smile upon warpage.
Design a model in digital, and invert.
Using a 3d printer, print a two part mold.
Have two part mold cast sacrificially into bronze.
mount bronze molds in steel holders. This is to keep overall stress levels down so the bronze molds don't fatigue.
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Plastic to be used is ABS, can be made plastic (ie squishy) quite easily using boiling water. Or a filament nichrome wire extruder nicked off the RepRap project.
Milk cartons, coke bottles and shampoo bottles ect are all made of ABS.
Pressure holding moulds together to be achieved using a gingegvery pattern DIY press, or a modified drill press
Possible issues
- insuffiecent mold life for investment
- Air bubbles
- Plastic setting too quick to take the details.
Possible solutions:
- experiment ÂÂ
Good design may help - avoid stress concentrating details (will post alter about this if people want)- if the plastic is under high pressure, air bubbles should be squeezed smaller. good mold design should help here too.
- Heated molds seems the obvious solution. water baths, nichrome wire, a blowtorch or even a quick sit in an oven before use. ABS never truly melts but it does go hard quuite fast. As the large lumnps of metal surronding it should cool a bit faster though it should give the plastic a chance to 'anneal' reducing the chance of warping.
