Ibrahim Kocaalioglu   posted here about 3D printing materials yesterday.

3D Printing
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@Ibrahim_Kocaalioglu posted here about 3D printing materials yesterday. The thread contained a link to this which I call “Lost Wax Investment Casting” Which I have singled out for this thread. (See Below)

Basically you substitute PLA for the Wax

It had occurred to me to try and develop a method of printing an object with wax for just such an eventuality, never even considered the idea of using the PLA directly as a substitute for the wax! It really pays to be a member of such a group as this…

Also linking this back to a recent thread on printing components for radio controlled vehicles, https://plus.google.com/u/0/104012815742569035024/posts/ge1hbZvyu9d

I note the floor pan of some radio controlled racing cars is made from aluminium. This method of “lost wax investment casting” would lend itself to printing that RC component I reckon.
http://3dtopo.com/lostPLA/index.html

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I NOTE: >>>> I made the plastic part perfectly fit the extrusion, then printed it again at 102%. The extra 2% is precisely how much the aluminium shrunk as it cooled.<<<<<

I was wondering about the shrinkage…

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@Sebastian_Kuzminsky has been involved with PLA-based lost investment casting; it seemed to work pretty well. Foundries regularly use (and you can buy) margin rulers that are calibrated to account for material shrinkage for mold-making – although presumably you’ll be working from CAD and need to scale in software rather than in hardware. Typically metals were cast with a slight machining tolerance and then machined down to fit the application with precision surfaces.

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Aluminum 1.0–1.3% 1⁄8–5⁄32 in/ft shrinkage allowance depending on the alloy content. Overall, I have found the lost ABS/Foam/PLA/Wax casting processes quite useful.

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Over the last three months or so I’ve been experimenting with using ABS to do the same thing, and it worked out really well for me: http://jason-webb.info/2012/11/lost-abs-experiment-with-3d-printed-objects-and-aluminum-casting/

I used the process to create an aluminum two-part mold (seen in that post), and three bronze supershapes that I printed in ABS on a Replicator: http://jason-webb.info/2012/12/cast-bronze-supershapes-from-3d-printed-forms-using-the-lost-abs-process-with-cast-aluminum-cradle/

Just for fun, you can actually cast other materials directly into ABS molds (if the investment casting process isn’t a possibility for you). I’ve tried gelatin, resin, silicone and even wax! So much more to explore, but I thought you’d like to see whats possible :slight_smile: http://jason-webb.info/2012/11/wax-casting-with-3d-printed-two-part-molds/

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I can’t wait to try this…