Casting metal and 3D printing go together like nuts and gum, and there are no shortage techniques that use the two together. Lost PLA casting is common, and sculptors are getting turned on to creating their works in plastic first before sending it off to the foundry. Now the folks at FormLabs have turned the whole ‘casting metal and 3D printer’ thing on its head: they’re printing sacrificial molds to cast pewter.
There are two techniques demonstrated in this tutorial, but the real winner here is printing a complete sacrificial mold for pewter miniatures. While this technique requires a little bit of work including washing, curing, and a bit of post-processing, you would have to do that anyway with anything coming out of a resin printer.
The material of choice for these molds is a high temp resin with a heat deflection temperature of 289 °C. Using a pewter alloy that melts at 260 °C, casting a metal miniature is as simple as pouring molten metal into a mold. Demolding might be a little finicky, but with a small screwdriver used as a chisel, it’s possible to get the cast newly parts out.
We’ve seen pewter casting with PLA, but the quality available from the Form resin printers is truly amazing and produces some great looking miniatures.
[TheBackyardScientist] at it again with another super villain-esque demonstration of gadgetry: a liquid metal squirt gun.
The squirt gun has a compressed air tank like most others — more on that later — but to fire its primary ammunition, a nozzle that connects directly to an air compressor is needed. Again, like most guns of this nature, air is forced into the gun’s reservoir, displacing the pewter and expelling it out the gun’s barrel. Yes, pewter.
Working around the heat tolerances of thread seal tape, pewter has a low enough melting point that an airtight system is preserved — plus it’s really cool to fire a stream of liquid metal. The ammunition is made from pewter ware melted down and cast into pucks. These pucks are stacked into the gun’s magazine, melted with a propane torch and carefully loaded into the gun.
The built-in compressed air tank lacks the oomph to push out the pewter — hence the air compressor, but any lighter liquids or condiments are fair game for rapid-fire exercises. Yes, condiments.
Continue reading “Wield The Power of Molten Metal”
Over on Hackaday.io, [bms.had] is showing his technique for 3D printing molds that he uses to cast (lead-free) pewter objects. The process looks simple enough, and if you have a 3D printer, you only need some lead-free pewter, a cheap toaster oven, and PLA filament. He’s made two videos (below) that do an excellent job of showing the steps required.
Even though the pewter is hot enough to melt the PLA, it doesn’t appear to be a major problem if you quench the piece fast enough. According to [bms.had], a slower quench will melt some PLA although that creates a smoother surface. You can see the 0.31 mm layer lines in the cast, though, although you can use any layer height you like to control that. Creating the mold is simple (the videos use Tinkercad, although anything suitable for creating 3D models would work). You essentially attach a funnel to your part and make the entire part a hole inside an enveloping shape.
Continue reading “Pewter Casting with PLA”
[TheBackyardScientist] has been living up to his name, this time by casting a pewter sword in his yard. Pewter is a soft alloy of mostly (85–99%) tin along with copper, antimony and bismuth. Older pewter castings often used lead as well. The great thing about pewter is its low melting point of 170–230 °C. At such low temperatures, pewter can be melted down on a common hot plate. Think of it as an easy way to get into the world of metal casting – no forge required. Of course, anyone who has been splashed with solder will tell you that hot molten metal always deserves a lot of respect.
[BackyardScientist] obtained his metal by hunting the local thrift stores. He used the “lost foam” method of casting, by carving a sword out of styrofoam. The sword was embedded in a 5 gallon bucket of sand with a riser to allow the mold to be filled. The pewter was melted on a cheap hot plate, and poured into the mold. The hot metal melts the foam on contact, simultaneously filling up the cavity left over in the sand mold. [BackyardScientist] was left with a solid pewter sword. It won’t hold an edge, but it is a great illustration of the technique.
Click past the break to see [TheBackyardScientist’s] video.
Continue reading “From Scrap To Sword: Casting Pewter”
Sandcasting at the beach
[mkb] sent in a video he found of [Max Lamb] sandcasting a stool at a beach in England. The material is pewter, or >90% tin with a little bit copper and antimony thrown in for good measure. While we’re sure there will be a few complaints from environmentalists, it’s still a cool video to see.
Your project needs an OLED display
Here’s a Kickstarter for a tiny 96×16 OLED display. Connect this thing to any I2C bus and you get a 15×2 character display (or a graphic display if that’s your inclination) very easily. Thanks to [Chris] for sending this one in.
Here’s one for a larf
[Ryan Inman] is suing 20 companies because he got mercury poisoning from vacuum tubes. Read that last line again. Most of the companies that sell antique/repro/hard-to-find components like Angela Instruments, Antique Electronic Supply, and even eBay are listed as defendants in the case. This might put at least one company out of business
even though they never sold [Ryan] a vacuum tube edit: they did sell him a neon bulb, and courts are generally idiotic when it comes to technological issues. It’s hilarious and sad, so we’ll keep you updated if we get more info.
Nostalgia, the pain from an old wound
The Adafruit blog posted an excellent piece on the Apple ][ game Rocky’s Boots, an educational game from 1982 that teaches kids how to connect logic gates. You can play this game in your browser, but we’d like to hear our stories of ancient video games that teach you engineering concepts like The Incredible Machine or Widget Workshop. Leave a note in the comments if we’re leaving any out.
A question posed to the community
A company is giving away credit card readers that plug into the headphone jack of an iDevice. [J Smith] writes in to ask us if anyone has gotten one of these and opened them up. Like [J Smith] we’re expecting something a repeat of the CueCat where free hardware is opened up to everybody. If you’ve done a teardown of one of these card readers, send it in.
[Mike] sent us a link to [neimod]’s Flickr photostream. It looks like we’re on the cusp of tearing open the Nintendo 3DS for homebrew apps. Someone who uses this much hot glue must know what they’re doing, right?