Lost PLA casting

If you want to create things in metal, there are folks using PLA plastic to do investment casting. DavidF from the SeeMeCNC forum is (as far as I know) the expert on the matter. Check out his process, it’s pretty cool! http://forum.seemecnc.com/viewtopic.php?f=41&t=5986

There was also a recent King of Random episode about it (using styrofoam, though), and I also found this HackaDay article: http://hackaday.io/project/2434/logs

I don’t know if I can share any specifics or not, but another one of The MakerHive guys is even formulating an SLA resin for investment casting.

Has anybody here done any metal casting? From a 3D Printed part? Please share!


I should also mention, there are some investment wax filaments on the horizon. I haven’t seen the report yet, but be on the lookout for DavidF’s experience on the matter.



Holy Moly this looks almost too cool for me…

Nowadays you really cannot try everything on your own, so many people making awesome stuffs out there and you will never know if you don’t walk out…

Thanks for your sharing, Jim. So glad to learn another brilliant project.

  • Hunter.
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That’s what I’ve been looking for. I’ve done lost-wax silver casting, and even used plastic. I don’t know how much residual ash PLA leaves behind after burn-out, though. It’s a definite area to explore. You can even use bronze casting beads…

Reclaim your own metals:
Grant Thompson/ The King of Random has made a few projects that may help with this.

He uses styrofoam but I think the process would be similar. - https://www.youtube.com/watch?v=tH-PaNugz9w

Make the metal foundry (Al can recycling) - https://www.youtube.com/watch?v=hHD10DjxM1g

Arc furnace (Zn or higher melting point metal recycling) - https://www.youtube.com/watch?v=VTzKIs19eZE


Found someone that has already done some PLA casting


Good info here. Recently I bought an injection molding machine and have been looking for ways to save on milling molds in metal. Have wondered about the lost-PLA method.

Yeah I was just going to reply to you that I’ve read about wax filaments you can print with to do metal casting. It is a really cool subject to talk about. The 3DPrinting company Shapeways is actually offering a castable wax material they can print with. Although they have very expensive machines to do that for them.

Here is a link to that page: http://www.shapeways.com/materials/wax

Also I have read about people printing positive models of their objects from plastic. Then using casting silicone or other materials to make the negative. Finally using that negative to make the final product. Yeah I know, that is a very long & tedious process. But its what you have to do for now, until something better comes out. :slightly_smiling:

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There’s another product I’ve seen online that is wax filament for 3d printers. It looked like the cat’s pajamas until I saw forum activity that described a problem. The user was unable to reduce the temperature of the print head to encompass the correct range for the material.

That’s something to be determined for the Flux Delta, isn’t it?

machinable wax filament

They other filament that you can look at is “MoldLay”, from the same people that make bricklay and several other specialty filaments.

Everything that I’ve seen, with a few exceptions, would be material that you make into a positive investment, encapsulate with layers of slurry and sand, and melt out before you cast your metal. The exceptions are people who’ve figured out clay extruders and a ceramic UV resin from Tethon that just ran a Kickstarter.

I was doing research on this topic because I am making the mini metal foundry from Grant Thompson and have a Pla 3D printer (from XYZ). I haven seen anybody pour metal directly onto the plastic so I don’t know if it will work or not, but that’s what I will find out. I plan on posting my results here, since it is one of the first places I looked, and I hope more people will see my results and be educated. My concerns are that 1. The metal (I will most likely use aluminum) will not vaporize the pla and something bad will happen, and 2. The pla will have moisture trapped inside of it, since that is a trait of pla, and will ‘explode’ like concrete does when hot metal is poured on it. Hopefully, though, the metal will be hot enough and the results will be similar to if I was using a foam or wax positive buried in sand. I am hopeful since aluminum’s melting point is 660 degrees Celsius and pla’s melting point is 175 degrees Celsius. As I said, I will post my results here. I expect to be doing this within 2 weeks, but, depending on school and life, that may increase. I’ll be back, Skullngloves. (One thing I forgot to mention is that I will be using a low infill and shell density so there is less plastic. That, I believe, will give me the best results.


Sounds interesting! Just make sure you’re behind something nice and solid (and preferably far, far away!) when that aluminium pours in just it case it does go off like a small bomb!

I did some Googling, and it looks like you can use PLA with aluminum. The main thing this article suggests is using as little infill (and probably perimeter) settings as possible.


Cool! Thanks for that article, I was wondering why nobody had done it before, but I guess I just didn’t look hard enough. And trust me, I’ll be safe. My dad has done lots of castings and we are both very careful when doing dangerous stuff. I might do a plaster mold, sand mold, or even both molds, so I’ll post my results here. Thanks, Skullngloves.


Did you try it since this last post? I’m gathering the materials to build the same mini foundry and have been wanting to do this since I got the Delta 1 year ago.

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I have and it didn’t really work. It just melted the top and then the aluminum cooled too much. I’m going to try some other time but won’t be able to for a long time. (Until school starts)

I’ve done lost-wax and lost-plastic casting of small objects for jewelry. You can even use dried insects! The best way to do that is to use jewelry investment (porous plaster) and use a kiln to burn out the wax / plastic model. You might be able to use a regular oven at 500 degrees, or maybe run it through a self-cleaning cycle to burn out the plastic. You might not want to coat your food oven with plastic fumes and smoke, though. After that, you can use a vacuum caster (you can get cheap ones) or a centrifugal caster to pull / force the molten metal into the cavity.
Here’s a youtube using the centrifugal method: https://www.youtube.com/watch?v=Aub_UpFereQ

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Which entry level vacuum setups are worth looking at?

As you see from looking at Amazon, etc. there is quite a range of prices. Many of those vacuum machines, though, are mostly for pulling a vacuum on the liquid investment to get any bubbles out. That can be useful for intricate pieces, but not always necessary if you’re careful about painting your piece with investment beforehand. My own vacuum caster is a very simple setup with a manual suction piston. It’s for small pieces and is intended for jewelry. There’s one for sale (overpriced) on eBay:
This one seems to be the simplest full vacuum setup, but you’d need to supply your own source of vacuum. http://www.grobetusa.com/vacuum-assist-table-item-no-21-806g/
The cheapest vacuum source is a water-faucet venturi that uses water flow to create a fairly good vacuum.

There’s a lot of information in this thread, and some of it is correct. But as a long-time metal caster, there are some errors that strike me.

First off, the idea that the positive model will be cleanly and instantly replaced by hot metal is wrong, if you’re talking about a model made from PLA, or even wax, and encapsulated in a plaster-based or ceramic shell mold. There is a process that works that way, but only with models made from polystyrene-based foam, and only when it’s encased in loosely packed sand.

Models made from other combustible materials need to be fired in a kiln (not baked in a home oven) to burn away the model before introducing the metal to the mold. The model must be completely gone, without a trace of carbon or any ash left in the mold. Failure to do this will result in surface defects or incomplete castings, and can lead to dangerous explosions, especially if the mold is gypsum plaster based, which retains chemically bound water up to 1000 degrees F. Wax models are usually fired to 1250 degrees or so, but PLA, which doesn’t flow out of the mold when heated, like wax does, needs more heat and time in the kiln; about 1450F is typically recommended. (Introducing extra air into the kiln during burnout helps combust the residual ash.) This is where conventional plaster-based jewelry investment - a mixture of gypsum plaster and silica flour - reaches its temperature limit, so other formulations can work better. There are investments made for platinum which can tolerate more heat, and also some made especially for plastic burnout. Ceramic shell is another alternative, but it’s a lot more hassle to set up and much slower, since successive layers need to be applied and dried to build up a sufficiently thick mold.