Mantis

I'm not melting aluminum with this kiln. It's for drying 1-2 liter plaster flasks and burning out the PLA plastic investment inside them (less than 100 grams), over the course of 6-12 hours. My btus/hr are about 7000, which pottery websites say is about three times what I need for my volume. My stove-top has no trouble melting 2kg+ of zinc, so there should be no issue getting a couple liters of slowly moving air to the same temperature. For Aluminum melting I already have an effective, if janky, solution in the form of two earthenware charcoal stoves stacked on top of each other. The charcoal and blower tube goes in the bottom one, the crucible in the top one. It just fits a fire extinguisher crucible. I'm planning on building a better, waste oil powered one soon. We definitely have toilet paper rolls, but I don't actually recall seeing concrete tube formers, though I'm probably just not looking. I can print the size I need for less than $3 of plastic, which is cheaper than the gasoline to get to a home center. The form gets printed in "vase mode" which only prints the outside lines so it only takes a couple hours. It felt ridiculous to me too at first, but honestly it's cheaper and more convenient to do it this way. A bunch of further questions: I'd like to find porous investment plaster so I can vacuum my castings after they are poured. I'm having trouble finding it for sale (my Japanese is decent but I'm not a native). There's a plaster mix called Hi-stone C-2 (ハイストーンC-2) that the manufacturer recommends as it's designed for high heat, but they don't say anything about porosity. Could I mix the fine sand I use for sand-casting into that plaster to make it more porous? Is leaving a freshly poured casting in a vacuum chamber until it cools a good or a bad idea? I'm thinking doing it this way would make my aluminum cool very slowly, with good crystal structure and without oxidation or air absorption. Would this make the aluminum undesirably soft though? Since my kiln won't be getting anywhere near the limit of my refractory, could I blend a bit of dish soap into my refractory cement to foam it for improved insulation? Does anyone know of a pottery supply store in Ibaraki? Or at least what word to plug into Google maps?

Sorry if this is the wrong forum. I'm building a small kiln from a propane bottle. I'm planning on using it exclusively to burn out 3D printed parts from plaster molds, so I can pour aluminum into them. It will need to get up to 600c and maintain a very slow airflow (convection is probably sufficient, or I could install a tiny computer fan) so the PLA vapors can escape. Since I've almost managed this temperature with a large un-insulated gas barbecue, I imagine a small propane camp stove burner will be fine for the well insulated 8 liter volume I'm planning. The ports on the side and top will be for adjusting airflow, with the side one also giving me a way to light the burner. The bottom one feeds the burner and hopefully stops it overheating. Perhaps I'll make it height adjustable. The lower stick will support a grill to hold my plaster cast and drip pan. My refractory is "Asahi Caster" and is rated to 1500c. I'll also be using rockwool for extra insulation. The top comes off at the seam on the tank. (I forgot to put a seam in the refractory part of the 3D model but it'll be at the same place.) I already have a 3D printer, so I'm going to use it to print the cavity form, then remove it with a torch and pliers once the refractory is ready to fire. As such the sky is the limit for chamber, vent, etc design. Can someone with more fluid dynamics knowledge than me offer any advice? How does it look as it is now? What would you change?