Hi to the forum. I want to get started in 3D printing specifically to make models for lost wax casting. Instead of carving originals in wax I would like to print them and melt them out of the plaster just like normal. To this end I need the lowest melting material I can find. My research to date suggests that this is PLA. I have seen figures of 350 F for this material. That would be great since I could melt out the moulds in a normal kitchen oven. Is anybody in the group doing this?’
3 Likes
Lernerg
2
Its a little pricey, but this stuff would be ideal for what you are looking for. I haven’t personally tried it out, but it should do the trick. I have also used a oven to melt PLA out of a hotend, and while it does melt, it doesn’t really flow out like wax would. Good luck!
Edit: I just found this project where someone uses PLA instead of wax.
The moldlay seems to be designed for investment casting. I noticed a comment in their question list about difficulty getting detailed prints with it. Would probably take some experimenting with setup on the printer. The fellow using PLA burned it out at much higher temps than an oven. Seemed to work well. Good info. Thanks a bunch.
garthvh
4
I have printed quite a few models for casting with machineable wax filament. Melts at 140C. Your prints max out at about 4 hours and it does a terrible job with support.
By support do you mean poor results with overhangs? Is the material too soft to maintain a complex shape?
garthvh
6
It is fine with overhangs that don’t require support material. The thin support structures crack and warp up ruining the part if they are more than a few layers thick, I have not had any success with models that required support for more than a few layers.
Most of the parts I have printed had channels built in as well, and those have to print without support too.
Take your 3d object, use a silicone rubber molding product and cover it. Once it hardens, remove the rubber and place it in a bin of sand for support. Then just pour in your melted wax, let harden and voila, your object is now wax. You’ll probably need to work on it a bit but it should get you 80-90% complete depending on the complexity and shape. If really complex, you can print your 3D object in sections, create multiple rubber molds creating several wax pieces of your sculpture. Then you assemble all the wax pieces of your object and melt them together with a hot knife. You can also create a simplified version of your object without extreme detail if it is a problem, then create the detail pieces by hand and assemble. Again, it isn’t perfect but expedites the process tremendously.
Google silicone rubber mold tutorial
Yes it certainly could be done that way. My objects are miniature gas engines for aircraft models. These parts require complex cores for all the hollow spaces in the engines. Creating these cores in silicon molds is difficult. I would love to be able to go directly from my cad designs to a printed part that can then be directly investment cast without all the intermediate steps of creating a silicon mold and core boxes.
Enza3D
9
@Skygeezer65
What are you casting the models with?
Models are cast in aluminum. Depending on alloy it pours at 12-1400F
Enza3D
11
Another option you have is using an SLA printer with Castable resin. It works beautifully in a Form 2, and really produces very nice results. It is designed to burn-out (not melt) so you may have trouble with it if you can’t follow the burn-out cycle, but the results are impressive.
Interesting. I am just starting in all this so don’t know all the processes yet. Burning out resin shouldn’ t be difficult but I would worry about ash in the mold. Do you have a reference for this process?
Enza3D
13
Yes, there is a specific process outlined by Formlabs for using the Castable resin. I know of several jewelers who have used it, and when properly cured then burnt out, it left little to no ash residue behind.
You can read more about it here - https://formlabs.com/media/upload/Recommended-Burnout-Process.pdf
It is critical that the curing is done properly; an improper cure will result in poor burnout and porous surface finishes on the final casting. If you plan to use a 3rd party, I would suggest finding a local jeweler who has access to/experience with a Form 2 and let them print/cure the print for you. Or find a Hub that can prove they know how to use this resin and cure it properly. Otherwise you will continuously get less than ideal results.
