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Aug. 21st, 2018 11:37 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
randomdreamsI was going to try casting another form Sunday night, but got started too late, and burning out the 3d printed material from the mold took way too long. Last night I fired up the oven and completed the burnout. I've learned the mold should have no trace of melted plastic on it: it should be dusty brown where the material has vaporized.
Tonight I loaded the crucible with aluminum, fired up the foundry, then came inside and had dinner, and by the time I got done, the aluminum was molten and just ready to pour, so it took about ten minutes of actual time to go from start to finished. I'm getting a lot faster at every part of the process except for burnout time.
is what it looked like right out of the plaster mold.
A little cleanup yielded this:
There is a casting flaw on the bottom because the wall thickness was too narrow (and possibly because the mold was cold when I poured: usually I pour when it's just come out of the burnout oven, which means the aluminum doesn't freeze quite as quickly.)
But the important part is the base and hemisphere. I can cut off this section, and machine a new one out of aluminum on the lathe, then weld it to the base.
Here's the part I really like: straight out of the investment, 3 out of 4 bolts go through and into the head, and the fourth doesn't because there was an air bubble in the investment that produced an aluminum lump which prevents the bolt going through the hole. That's okay. When I move to jewelry investment, that cures more slowly, I can vacuum it and not have to worry about air bubbles anymore.
Tonight I loaded the crucible with aluminum, fired up the foundry, then came inside and had dinner, and by the time I got done, the aluminum was molten and just ready to pour, so it took about ten minutes of actual time to go from start to finished. I'm getting a lot faster at every part of the process except for burnout time.
is what it looked like right out of the plaster mold.A little cleanup yielded this:
There is a casting flaw on the bottom because the wall thickness was too narrow (and possibly because the mold was cold when I poured: usually I pour when it's just come out of the burnout oven, which means the aluminum doesn't freeze quite as quickly.)
But the important part is the base and hemisphere. I can cut off this section, and machine a new one out of aluminum on the lathe, then weld it to the base.
Here's the part I really like: straight out of the investment, 3 out of 4 bolts go through and into the head, and the fourth doesn't because there was an air bubble in the investment that produced an aluminum lump which prevents the bolt going through the hole. That's okay. When I move to jewelry investment, that cures more slowly, I can vacuum it and not have to worry about air bubbles anymore.
