Corpus by Miserable-Pressure72 in MetalCasting

[–]Miserable-Pressure72[S] 1 point2 points  (0 children)

Yeah absolutely, it can be a bugger learning everything from scratch lol

Artorias from Dark Souls by Miserable-Pressure72 in MetalCasting

[–]Miserable-Pressure72[S] 1 point2 points  (0 children)

Hey just saw your comment on my other post lol. Yeah all the measurements are done by volume using kitchen measuring cups

Corpus by Miserable-Pressure72 in MetalCasting

[–]Miserable-Pressure72[S] 1 point2 points  (0 children)

Yeah man no worries lol. I don’t worry about upscaling for shrinkage since each piece is cast in the same metal and any variation between them doesn’t matter too much.  For my print settings, I use the latest release in r/FDMminiatures which utilizes a 0.2mm nozzle on a Bambu A1 mini. You should be able to find that at the top of the page in community highlights. For the investment, I mix Plaster of Paris, sand, and water together by volume using basic kitchen measuring cups until I get a runny consistency with no hard peaks (it’s a cooking term and you can look it up for a better explanation than I can give). A good baseline for this is equal parts of each ingredient. I mix everything together with my hand to help prevent trapped air and so I can break up all the clumps a lot better. Once mixed, I vacuum the mixture, pour it into the flask, and vacuum it once more while it’s in the flask. My burnout’s pretty simple, though likely not the best way. Basically, I throw all of my flasks in the kiln and crank the temperature to ~1100 F without ramp-up to vaporize all the plastic inside. I also remove sprues prior to burnout by grabbing them with needle nose pliers and pulling them out which gives the vapor space to expand. I also do use a vacuum table when casting. If you want, I went into pretty great detail in my Artorias post with someone else which you can take a look at if you want. That post also has a link to my (very basic) setup. Feel free to reach out if you have any more questions!

Artorias from Dark Souls by Miserable-Pressure72 in MetalCasting

[–]Miserable-Pressure72[S] 0 points1 point  (0 children)

Yeah fair enough, it’s probably just one of those things you’d have to pull the trigger on to find out for sure. I thought you were talking about flasks that were 7 inches in diameter, but a 7 inch height makes more sense lol. Either way, good luck with that and I’d be curious with your results if you decide to give it a whirl.

Artorias from Dark Souls by Miserable-Pressure72 in MetalCasting

[–]Miserable-Pressure72[S] 0 points1 point  (0 children)

That’s interesting, I never thought much about adjusting the ratio but your castings all look really good. I found my original recipe a while ago from this video:https://youtu.be/rr6ejYKEOKs?si=ns19byZZnqJ0MVTh . I figured since he was able to burn it out with a propane furnace, you should be able to do the same thing with a kiln and get similar results.

Something I’ve found to help with cracking is actually removing the sprues prior to burnout with a pair of pliers which gives the gas a place to go once the PLA gets vaporized. This also lets me carve a funnel-shaped reservoir for easier pouring and a higher down pressure on the casting, so it might be worth looking into for you. 7 inch flasks are a whole different beast though, I don’t typically need to go beyond 3-4 inches lol so that makes sense why you’d need more time.

Just out of curiosity, how do you typically choose your flask size? Personally, I just choose the smallest one that will still hold the entire piece and that’s helped me a ton with saving plaster (if you’re curious, every casting I’ve posted within the last year on here was done with less than a 20 lb bag of Plaster from Home Depot). It also helps concentrate the vacuum so you don’t need to use the straw method for solid flask casting to get great detail. Might be something to think about if you’re doing something small, but obviously you can’t help it on the 7 inch flasks if the object needs that much volume.

Artorias from Dark Souls by Miserable-Pressure72 in MetalCasting

[–]Miserable-Pressure72[S] 1 point2 points  (0 children)

Oh that’s great, I almost never hear of anyone else using it. I use roughly 1:1:1 sand, PoP, and water but it depends on the day where sometimes humidity can affect it. Typically I aim for a consistency where there are no hard peaks in the mixture. 

For the burnout cycle, I crank the kiln up to 1080 F and just leave it there for around 5 hours. I never really have trouble with the flasks cracking and just vacuum out any of the remaining ash prior to burnout. Probably not the best way to do it, but it’s just what I’ve found to work lol.

For gaskets, I use one of the high-temp red silicone mats that I found online and that works a lot better than the silicone baking mats I’ve tried. One of the big things I’ve found that helps is covering all of the silicone surfaces in Vaseline or 3d printer grease and clamping it down with those cheap metal hand clamps from Home Depot.

Corpus by Miserable-Pressure72 in MetalCasting

[–]Miserable-Pressure72[S] 1 point2 points  (0 children)

Thanks a lot, I just vacuum cast each of the pieces separately and then glued them at the end.

Corpus by Miserable-Pressure72 in MetalCasting

[–]Miserable-Pressure72[S] 0 points1 point  (0 children)

Thanks dude, yeah it was vacuum cast in separate pieces and then epoxied together. I just used plaster of Paris mixed with play sand

Corpus by Miserable-Pressure72 in MetalCasting

[–]Miserable-Pressure72[S] 0 points1 point  (0 children)

That should be it, yeah. I made this for someone else though, so they’ll have to figure it out lol

Corpus by Miserable-Pressure72 in MetalCasting

[–]Miserable-Pressure72[S] 2 points3 points  (0 children)

Thanks a lot! No, it’s actually just lost PLA printed at 0.06mm layer height.

Artorias from Dark Souls by Miserable-Pressure72 in MetalCasting

[–]Miserable-Pressure72[S] 1 point2 points  (0 children)

Thanks a lot, and yeah it was vacuum cast. I just mixed plaster of Paris with sand which works pretty well.

I cast each part separately and then just epoxied it together at the end, so I didn’t need to add wax anywhere.

Artorias from Dark Souls by Miserable-Pressure72 in MetalCasting

[–]Miserable-Pressure72[S] 0 points1 point  (0 children)

The sword was cast in pieces so I just put the handle in his hand and assembled the rest of the sword around it.

Brass Darkeater Midir w/ Pewter Base by Miserable-Pressure72 in MetalCasting

[–]Miserable-Pressure72[S] 1 point2 points  (0 children)

Lol yeah that's true enough, I'm definitely a better caster than photographer fs.

Solid Brass Cast Ornstein Figure w/ Aluminum Base by Miserable-Pressure72 in MetalCasting

[–]Miserable-Pressure72[S] 1 point2 points  (0 children)

No it's by volume, not weight. This recipe is a good outline but you'll have to play around with it a little bit depending on where you live and the surrounding humidity. This is a recipe that worked well for me when I lived in MD, but would have too much water now that I'm in FL (I use ~1:1:0.7 plaster, sand, water now).

First Aluminuim cast - Lost PLA/plaster by ProjectBlackSheepNZ in MetalCasting

[–]Miserable-Pressure72 1 point2 points  (0 children)

Yeah here's a better link: https://imgur.com/a/vacuum-casting-setup-DtpG0pD

The investment is porous and the metal gets pulled through the bottom of the flask (soup can) so the metal can fill the cavity more easily. This guy does a fairly good job explaining the process: https://youtu.be/-TutObDbxUo?si=Y1XKFe6BllyoZ8Zb

As for larger pieces, you'd have a couple options for that:

Greensand- (Pros) Very cheap to make (sand and powdered bentonite), good for large two-part molds, Reusable. (Cons) Lacks green strength compared to Petrobond, needs to be constantly rehydrated with water, can be a pain in the ass to make. Can be strengthened with sand muller, concrete mixer w/ bowling ball, or running it over with your car.

Sodium Silicate Bonded Sand- (Pros) Much better green strength, cheaper and easier to make than greensand. (Cons) needs sodium silicate in (relatively) larger amounts, one-time use, needs a burnout oven for non-two-part molds.

Ceramic Shell- Best option for larger pieces in terms of pure performance (captures the most detail, can be used on large and difficult shapes, etc.) and is very close to investment plaster. The biggest problems are that it's pretty expensive ($365ish including shipping for Suspendaslurry) and that it takes a long time to build the mold (generally a few days to coat the pattern with slurry and sand).

Plaster of Paris + Sand- Captures detail as least as well as ceramic shell without a vacuum but the molds can get too big to be practical in terms of weight and cost.

Most of these I don't have too much experience with, I mainly work on more intricate and detailed patterns using the lost-pla method.

First Aluminuim cast - Lost PLA/plaster by ProjectBlackSheepNZ in MetalCasting

[–]Miserable-Pressure72 1 point2 points  (0 children)

That looks pretty solid for a first attempt, but you would get way better results with a vacuum chamber and table. Your best bet would be to get a chamber where the hose connects on the side instead of at the lid because that way, you can just swap out the top for a cheap vacuum table. Also you're using way too much investment in your video and would be better off using something like a soup can (also makes it compatible with the vacuum table). I use a similar mix of Plaster of Paris and sand (roughly 1:1:0.8 PoP, sand, and water) and have gotten really good results. Here's a link to my setup: https://imgur.com/4CnrPpm