About this 3D model

*Cosmonaut figure as Lucifer, the Lightbearer.* See my video for an overview of casting metal figure directly into printed ABS mold: http://youtu.be/ZvKtsrt9kTo ******** I'll try to write these notes out in a tidier format soon, but I'm totally high on molten bismuth fumes at the moment, so it's stream-of-consciousness for now: ******** [UPDATE: I have to point out that all the low temp "cerro--" alloys have lead and cadmium, and are toxic. You need to use proper ventilation, and keep it away from food preparation areas. In fact, I'm going to be looking into "Field's metal", which has neither lead or cadmium, and I'll report back how well that works in ABS. The objects you make *won't* be suitable for food preparation or food containers or utensils of any kind, and probably not for kids' toys either. FWIW, I've seen several gunsmithing how-to videos that don't mention toxicity of the Cerro-lines at all, and they aren't using ventilators either, but they should. For all I know it gives off gamma rays too. Here are some Material Safety Data Sheets I found: http://www.bendalloy.co.uk/Cerrosafe.pdf http://www.alchemycastings.com/pdf/Low158-190%28Safe%29.pdf And some usage instructions, with no mention of ventilation or toxicity in normal use: http://www.brownells.com/userdocs/learn/Inst-446.pdf http://www.brownells.com/userdocs/documents/bt002015.pdf http://www.brownells.com/.aspx/lid=10667/guntechdetail/Cerrosafe-sup-sup-The-Gunsmith-s-Secret-Weapon Use at your own risk. If you want to try these molds with friendlier materials, you might try casting simple plaster of Paris in the "Lamassu" (winged bull creature) mold. That one is a thin, break-away mold: no solvents required. See the photo I've added.] **Casting bismuth alloys directly into printed ABS molds:** I've uploaded the .stl of the mold shown in the video, as well as my gcode and sg3 files. With these the finished figure is about 2.25 inches tall. I have printed this figure a bit larger with much better results - the bigger it is, the better the detail-to-defect ratio. It just consumes a lot of metal - and I ruined the bigger casting trying to grind the plastic off. The mold envelope of the "Mold" stl is much more bulky than necessary, and wastes plastic and print-time, and dissolve-time. I just haven't had time to make a more close fitting one. I've included the figure's "positive" stl too, if you want to redesign the mold shell (or just print the figure in plastic). This process is related to lost wax casting, but the "manufacture" of the original object happens onscreen, and the wax burnout step is skipped completely. In theory, any print-problematic overhangs should translate into air pocket problems, but at the small scale I've been working at, I haven't had any problems; the metal is thin and heavy enough it's displaced all the air pockets no problem - just a little tapping here and there. If you work at a larger scale, or have air void problems, you may have to start printing in several pieces, or using vents and sprues, olde school style. But just design them into the object! I've been playing with bismuth alloys off and on for a couple weeks now, but I haven't been making controlled tests or keeping careful notes, so I don't have a completely reliable workflow figured out. Some of my castings-in plastic turn out well, some don't. For example, the low-relief Lamassu (winged bull figure) also shown in the video turned out much sharper than my Lucifer figure. Why? Good question. There are a couple different bismuth alloys out there under a variety of trade names, including "Cerrosafe" (which seems to be the most popular), and "Cerrobend". Gunsmiths use them for taking casts of rifle chambers and barrels. It has a very low melting point – around 158F, and it flows very thin. Its melting point is actually lower than ABS' so... do the math. [UPDATE: I have to recommend trying "Field's Metal", even though I haven't tried it myself, not the "Cerro---" products. "Field's Metal" has neither lead or cadmium in it, and should be safer to work with. Please do your own research into the best alloy for your purposes.] The manufacturer of the "Cerro" line seems to have been bought out, and I'm not sure which alloys are which from the new supplier. I've just been buying "bismuth casting alloy, 158 Degree Melting Temperature" from McMaster-Carr ( http://www.mcmaster.com ) It seems to take pretty good impressions of fine details. From what I've read, the metal contracts a bit over the first half an hour after it's solidified, and I haven't figured out yet if that's good or bad for my purposes, or how I should try to time my work in plastic. Bismuth is machineable; a dremel cuts through it really easily. It's also drillable, sandable, and, I believe, weldable (not sure on that one though). I don't know how well it polishes, if at all, but it's bright silver when cut or freshly cast. One of my plastic molds (the Lamassu figure) was a tear-away - no acetone - so