Fantastic ! this motivates me to finally get into casting? Thanks for the great posts.
the aluminum castings you see in the photos are obtained after the second attempt, the blue PLA mold are those of the first attempt, the castings were not of good quality, I had 2 types of problem, cracks in the plaster and the aluminum did not fill all cavities. In some areas the thickness is about 2.5 mm and if the temperatures of aluminum and plaster are not correct, the aluminum does not penetrate uniformly. I repeated the whole process turning the models upside down for slower cooling and more pressure.Foketry:
Those castings look great. You should post some of your castings on thehomefoundry.org. They have a Lost PLA forum and I'm sure the guys there would be interested in this work.
I've got a couple of questions:
1) What do you use for an investment? You say plaster but it almost looks too grainy for plain plaster, sand added maybe? Is this something you bought, or is it a home-brew?
2) How do you pour into the molds? In your picture of just the molds, it looks like the molds are open topped. But in your picture with the molds in the burn-out oven it looks like there's been something added to the top of the molds. Did you add some type of a pouring basin?
3) You show approximately 4 hours at 550, I'm assuming 550°C? Any ramp up time, or ramp down time, or is that your entire burn-out schedule?
4) Do you pour immediately after burn-out with the mold hot, or do you cool the mold?
5) Do you use a vacuum assist during the pour?
6) How many attempts did it take to get the castings shown? If you are able to do this in one shot then thehomefoundry.org will definitely want to hear from you. They'll be jealous and want to know what you do to get such results.
Don
A vacuum table would probably help the thin sections fill. But getting those results on your only your second attempt with these parts is no small achievement - it's a pretty big deal.
It sounds like you're using a combination of the ceramic shell method and the investment block method, to take advantage of the best of both worlds.
What ceramic power do you use? The slurries used for ceramic shell sound like they are much thinner than what you are using. It takes several coats of sand and slurry with them to achieve the 4-6mm thickness you mentioned. Usually with a substantial drying period between each coat.
How difficult is it to de-mold the part when it's cast? I know the plaster will pretty much dissolve in a bucket of water, but how hard is it to remove your ceramic shell?
I'm not doing any casting yet, but I've got several projects in mind where cast parts would be almost a requirement. I've got a 3D printer, and I'm getting better at 3D CAD, With Lost PLA increasing as a casting method I'm slowly picking up some of the required skills.
I agree with you regarding personal safety, common sense rules - liquid metal is UNFORGIVING. There'll be no "What happens when you pour molten salt into an aquarium filled with water?" type of experiments for me. I like my skin the way it is. In relatively one piece, and not boiled, broiled or baked.
Don
A vacuum table would probably help the thin sections fill. But getting those results on your only your second attempt with these parts is no small achievement - it's a pretty big deal.
It sounds like you're using a combination of the ceramic shell method and the investment block method, to take advantage of the best of both worlds.
What ceramic power do you use? The slurries used for ceramic shell sound like they are much thinner than what you are using. It takes several coats of sand and slurry with them to achieve the 4-6mm thickness you mentioned. Usually with a substantial drying period between each coat.
How difficult is it to de-mold the part when it's cast? I know the plaster will pretty much dissolve in a bucket of water, but how hard is it to remove your ceramic shell?
I'm not doing any casting yet, but I've got several projects in mind where cast parts would be almost a requirement. I've got a 3D printer, and I'm getting better at 3D CAD, With Lost PLA increasing as a casting method I'm slowly picking up some of the required skills.
I agree with you regarding personal safety, common sense rules - liquid metal is UNFORGIVING. There'll be no "What happens when you pour molten salt into an aquarium filled with water?" type of experiments for me. I like my skin the way it is. In relatively one piece, and not boiled, broiled or baked.
Don
I also had the same problem with Chrome and also with Microsoft Edge, it would be interesting to log in, but there seems to be a problem, a security and invalid certificatesI don't want to derail this thread because it's one of the best on the HMEM, but I'd like to learn more about this side of things. I have a small vacuum caster and kiln from doing some silversmithing. Nothing is big enough to cast any of these models, but I'm at least a little familiar with the process.
I went to go look around at the Home Foundry, but I'm getting a browser error, which seems to be one of those security certificate date things. The "advanced" tab in Firefox says, "The certificate for thehomefoundry.org expired on 2/15/2018." It seems that with being expired over three years, I shouldn't be the only person getting that, so do you know anything about that? Have you been there lately? Is there another URL or something?
Bob
Enter your email address to join: