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Melting Metal with a DIY Foundry Furnace

Foundry Furnace

If you want to do casting at home, you’ll need a way to melt metal. [Jake]‘s DIY foundry furnace gets hot enough to melt aluminium, and is built out a mix of scrap parts.

The chamber of the furnace is built out of a water heater tank which has been lined with a special cement that refracts heat. The furnace is heated by a Babington burner. This type of burner works by atomizing the fuel and injecting it into the furnace. They are good for burning waste oil to achieve high heats.

A scrap Volkswagen oil pump and a cordless drill are used to feed oil into the burner. Once it’s fired up, the furnace takes about 10 minutes to melt the 11 pounds of metal that it can hold. [Jake] melted about 40 pounds of aluminium alloy from scrap alloy wheels in 2 hours, which should be more than enough for a home casting project.

After the break, check out the overview of the device and a demo of melting aluminium.

[Read more...]

Reproduce 3D printed models by making your own molds

Need fifty copies of that 3D printed whirligig you’re so proud of? It might be faster to just cast copies by using the 3D printed model to make a mold. [Micah] found himself in this situation and managed to cast one copy every 10-12 minutes using the mold seen above.

With the object in hand, you need to find a container which will fit the mold without too much waste. The bottom half of the mold is then filled with modeling clay, a few uniquely shaped objects to act as keys, and the model itself. After getting a good coating of release agent the rest of the mold is filled with a silicone rubber product which is sold for mold making. This creates one half of the mold. After it cures the clay and key objects are removed, everything is sprayed with the release agent, and the other half of the mold is poured.

Now your 3D object can be copied by pouring two-part resins in the to shiny new mold.

Turning 3D prints into aluminum castings

[Jeshua] needed a laser head attachment for a 5×10 foot CNC machine he’s working on. Because he has a 3D printer, [Jeshua] could easily print a laser mount and attach it to his CNC gantry, but that wouldn’t look very professional. Instead of decorating his gigantic machine with brightly colored plastic, he decided for a more industrial look by casting a laser head in aluminum using a 3D printed master.

[Jeshua] designed two parts for his laser cutter in OpenSCAD and printed them out on his 3D printer. A few bits of foam insulation were glued on to act as sprues, and an investment mold was made out of 1 part Plaster of Paris and 1 part playground sand.

After the mold had cured, [Jeshua] put is mold in a coffee can furnace to burn out the wax and foam. These hollow molds were placed in sand and the crucible loaded up with aluminum scrap.

The finished laser head fit his CNC machine perfectly – no small feat, considering [Jeshua] needed to take in to account how much the aluminum would contract after cooling. Not bad for one day’s work.

Building a casting furnace with heat exchanger

This completely DIY casting furnace turned out just great thanks to all the work [Biolit11] put into it along the way. He wanted to replace his older furnace with one that was more efficient, and to that end he built a heat exchanger into the design. This way the exhaust will preheat the intake air.

The furnace itself started with the shell of an old electric water heater. Excluding the design process, the majority of the build involved mold making. For circular parts he’s using quick tube, the paperboard forms used for pouring concrete footings. For more intricate parts he shaped polystyrene. They are layered in place and high-temperature cement is poured to form the permanent parts. After it hardens the polystyrene can be removed in chunks.

The heat exchanger is the part to the left. It includes several wide, flat pipes made of cement for removing the exhaust. Around those pipes a snaking metal chase carries the intake air which picks up the heat as it passes over the exhaust pipes.

For his first run with the new furnace he melted down a bunch of scrap aluminum and poured ingots.

[Thanks DC3]

Writing Javascript without using any letters or numbers

Did you know it’s possible to write Javascript code without using any letters or numbers at all? Well, it’s not just Javascript, but that’s the language used in this demonstration. [Patricio Palladino] shows how code can be written using just eight characters, and all of them are punctuation marks.

Typecasting is the name of the game here. By starting out with an empty array formed by a pair of square brackets, [Patricio] can generate the number zero by casting the array with the plus sign. From there he can use an exclamation point (a boolean cast) and addition to generate any number. The image above is an example of the digits 0-9. This would get very tedious for larger numbers but there’s another shortcut. Cast the digits to strings, concatenate them, then cast back to a number and you’re in business.

The technique is fascinating, and basically unreadable. As a proof of concept he wrote a parser that will convert any Javascript into this hieroglyphy. Check out his Github repository to give it a try.

[via Reddit]

Iron casting in the parking lot

Here’s one good thing about the bitter cold Midwestern winter, it helps keep you from overheating when working around a hot furnace. Back in February this iron pour happened in the parking lot of the Madison, Wisconsin based Sector67 Hackerspace. Look, they’re making iron hearts!

Now this isn’t just a bunch of members who got together and decided to do some casting. As you can tell in the video after the break the team knows what they’re doing. The event was a collaboration with FeLion Studios, a custom cast-iron art boutique. But the Hackerspace participants did get to take part in the process of building the cast, watching the pour, and cleaning up the rough results.

One of the people from FeLion Studios just appeared on the Martha Stuart Show, along with a 550 pound cast-iron frying pan United States map.  [Chris] from Sector67 tells us the New York frying pan that [Martha] is hold was a product of the parking lot pour.

[Read more...]

Sand casting motorcycle cases

Sand casting has been around since, well, since a really really long time ago. For thousands of years, people have been pouring molten metal into finely crafted sand casts, and there’s really no reason that someone can’t do the same thing in their garage or workshop today. This article covers the process of sand casting new case parts for antique Indian motorcycles.  In this instance, the parts were not only very difficult to find, the author also wanted to modify the design completely.

Though there are a few terms that pop up with which we’re unfamiliar, the process seems pretty straightforward. You build a model of what you want, you create the sand cast from the model, you fill the cast with molten metal. Done. In some cases, depending on the level of precision needed, you may need some machining done afterward. However, in many cases things don’t have to be quite so exact.

[via Matthew Van Arsdale]

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