Best Material and Solvent for Castings

Hi! If you're anything like me, you constantly have tons of ideas bouncing around in your head which makes it difficult to focus on one project and get it done. I've had an idea for a while and I finally want to finish it; that's why I'm coming to you guys.

Here's the idea: I've always liked the idea of metal 3D printing, but obviously it's impractical to purchase one at this time. I would love to be able to create any metal part I'd like for a low cost; but that's difficult to do right now. That's when the idea popped into my head of using a 3D printed plastic part to create a plaster mold, then cast a metal part in the mold. I know this isn't a new idea, but I thought it would be a good one. I did lots of research, built a metal foundry (and successfully melted some aluminum cans down), and I thought I was good to go. I don't actually have a printer of my own, so I placed an order to a random person from 3dhubs.com. When the part came, I casted it just as I planned; but when it came to the burnout phase, the project came to a screeching halt. You see, most people just use their foundry, but mine wasn't big enough. Others use a kiln, I don't have any access to any kilns. I thought I had a chance of just using a gas grill, but it didn't get nearly hot enough. I tried using a propane torch, but wasn't able to insulate the plaster mold well enough. At this point, I just decided to give up. A few months later, I had another great idea; I'd get my part printed in PVA filament, and just soak the mold in water to dissolve the filament. Sounds simple enough, right? Wrong. Didn't work again, the water simply was not able to dissolve the PVA as well as I would have liked. Another few months pass, and here I am again, thinking about the same project. I just can't get this one out of my head, because I think it really would be cool to get to work. My problem is getting the printed part out of the mold. Basically, I'm asking what filament and solvent should I use? I want a filament that prints well (the PVA prints didn't turn out that fantastically), but can also be VERY easily (hopefully almost instantly) dissolved by some relatively inexpensive solvent. Anyone have any ideas?

Thanks for your help!

... read through this pretty old post

[forums.reprap.org]

With the "low-temp melting" metals the mould could be made from silicone ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

... and here another thread with more infos, how to make the mould:

[forums.reprap.org]

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

a more recent eg [www.3ders.org]

Yes! Cold metal casting in silicone has definitely always been an option for me, but originally I was trying to cast a larger part, the silicone and a metal like bismuth would get very expensive very fast. It definitely still is an option for me, but I would rather cast with aluminum in plaster. Any ideas on filaments that can be dissolved very easily?

You could look at PVA filament, its water soluble but depending on where you are it can get expensive.

If you can get acetone cheap, you could always print a shell out of ABS then fill with acetone to dissolve it into a slurry that could be poured out. You would need an air tight cap to stop the acetone from evaporating, as some time, depending on the size of the cast it might take some time to dissolve.

Checkout myfordboy YouTube channel... does alu casting, just recently got a 3d printer

eg lost PLA casting [www.youtube.com]
Metal Casting at Home Part 72 3D Printed Core Box [www.youtube.com]

Edited 1 time(s). Last edit at 08/15/2017 10:16PM by Dust.

Aluminum cans are a really bad choice for casting. Try getting some aluminum (not magnesium) castings from an auto junkyard.

Agreed. cans are > 50 crap... paint, lacquer etc and what is left is very low quality and tiny quantity

If your lucky find a aircraft graveyard and buy a wing... should be lots of high quality alu in that

There is a filament designed for this, Moldlay.

It is a little like wax and you can use it to attach sprues to it etc.

Alternative, build a bigger forge? ABS with acetone to remove most of it and then burn it out with the forge.
If you place the mold over your forge while it is heating up, doe it not get hot enough?

If you have a forge big enough to melt the required aluminium, you must be able to burn out the filament.

Lykle

Another approach is to print a mould then use this to make a wax model. The wax model can then be potted in the plaster mould and melted out. You will be limited to designs where the mould can be disassembled without damaging the wax. You will also need to take care with printer resolution and removing the wax model as our printers produce ribbing on the sides that will "lock" the wax in place. Although some have use ABS + Acetone to smooth surfaces.
Dependant on how you get the printed mould apart you may be able to reuse them.
You can include runners in the 3D mould.
If you are happy to sacrifice the 3D mould you can use this as a former to machine the wax before removing it. For example you can drill a hole through the 3D mould with the wax inside and then remove the mould leaving a "fragile" wax with a hole through it.