Flip-Top Foundry Helps Manage The Danger Of Metal Casting

September 11, 2021 by Dan Maloney 18 Comments

Melting aluminum is actually pretty easy to do, which is why it’s such a popular metal for beginners at metal casting. Building a foundry that can melt aluminum safely is another matter entirely, and one that benefits from some of the thoughtful touches that [Andy] built into his new propane-powered furnace. (Video, embedded below.)

The concern for safety is not at all undue, for while aluminum melts at a temperature that’s reasonable for the home shop, it’s still a liquid metal that will find a way to hurt you if you give it half a chance. [Andy]’s design minimizes this risk primarily through the hands-off design of its lid. While most furnaces have a lid that requires the user to put his or her hands close to the raging inferno inside, or that dangerously changes the center of mass of the whole thing as it opens, this one has a fantastic pedal-operated lid that both lifts and twists. Leaving both hands free to handle tongs is a nice benefit of the design, too.

The furnace follows a lot of the design cues we’ve seen before, starting as it does with an empty party balloon helium tank. The lining is a hydrid of ceramic blanket material and refractory cement; another nice safety feature is the drain channel cast into the floor of the furnace in case of a cracked crucible. The furnace is also quite large, at least compared to [Andy]’s previous DIY unit, and has a sturdy base that aids stability — another plus in the safety column.

Every time we see a new furnace design, we get the itch to start getting into metal casting. And with the barrier to entry as low as a KFC bucket or an old fire extinguisher, why not give it a try? Although it certainly pays to know what can go wrong before diving in.

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Robert Murray Smith Discusses Rivets and Riveting

Old School Fastener Tutorial Is Riveting

September 10, 2021 by Ryan Flowers 18 Comments

Whether you’re making, repairing, or hacking something together, we all need fastners. Screws, nuts and bolts, and pop rivets are handy sometimes. Various resins and even hot glue are equally useful. In some cases however the right fastener for the job eludes us, and we need another trick up our sleeve.

[Robert Murray Smith] found himself in such a position. His goal was to join two pieces of aluminum that need a nice finish on both sides. Neither glue, pop rivets, screws, nuts or bolts would have been appropriate. [Robert] is always flush with ideas both new and old, and he resorted to using an old school fastener as explained as explained in his video “How To Make And Use Rivets“.

In the video below the break, [Robert] goes into great detail about making a simple rivet die from a 5mm (3/16”) piece of flat steel, creating the rivet from a brass rod, and then using the flush rivet to join two pieces of aluminum. The simple tooling he uses makes the technique available to anybody with a propane torch, a vise, some basic tools, and a simple claw hammer. We also appreciate [Robert]’s discussion of cold riveting, hot riveting, and annealing the rivets as needed.

Not only is riveting a technique thousands of years old, its advancement and application during the Industrial Revolution enabled technologies that couldn’t have existed otherwise. Hackaday’s own [Jenny List] did a wonderful write up about rivets in 2018 that you won’t want to miss!

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Building Fallout’s Super Sledge

May 31, 2021 by Lewin Day 7 Comments

The Fallout series of games has a variety of ridiculous weapons, not least the Super Sledge — a rocket propelled sledgehammer that looks about as dangerous for the wielder as it does for the opponent. [JAIRUS OF ALL] decided he had to recreate this build in real life, risks be damned.

Unwilling to go the single-use, solid rocket route for his build, [JAIRUS] instead elected to go with an electric ducted fan, supplemented with a propane supply for added flames. It’s not really a rocket of any form, and it’s unlikely the burning propane adds any real thrust, but it does shoot huge flames out the back and it is terrifying. The EDF idle speed can be set by a potentiometer on a servo tester hooked up to a speed controller, while there’s a valve for adjusting propane flow. A switch can then be used to boost the EDF speed higher and increase the propane flow, increasing the violence of the flow out the back of the hammer.

Notably, [JAIRUS] doesn’t actually demonstrate swinging the hammer at anything in particular. We’re kind of glad, as we suspect it might end with a sizable explosion, or burns at the very least. Nonetheless, it would easily be the most terrifying prop weapon at most any Halloween party you took it to. It’s in a similar vein to the fire vortex cannon [JAIRUS] also designed. Video after the break.

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Generator Runs On Natural Gas With Field Expedient Tip

March 3, 2021 by Tom Nardi 110 Comments

Many small gasoline engines can be safely modified to run on natural gas or propane with a kit that replaces the carburetor and adds a regulator, providing a reliable alternative fuel source in the event that gasoline is difficult to obtain in an emergency situation. This seat of the pants hack by [HowToLou] is definitively not the safe way to run your generator on natural gas, but if you ever find yourself in a situation where getting the power back on might be a literal matter of life or death, it’s a tip worth keeping in mind.

The basic idea here is that you feed natural gas (though propane should also work) directly into the engine’s intake by way of a hose attached to the air filter box. While cranking the engine, a valve on the gas line is used to manually adjust the air–fuel mixture until it fires up. It’s an extremely simple hack that, in a pinch, you can pull off with the parts on hand. But as you might expect, that simplicity comes at a cost.

There are a few big problems with this approach, but certainly the major one is that there’s nothing to cut off the flow of gas when the engine stops running. So if the generator stalls or you just forget to close the valve after you shut it down, there’s the potential for a very dangerous situation. Additionally, the manual gas valve will be at odds with a generator that automatically throttles up and down based on load. Though to be fair, there are certainly generators out there that simply run the engine flat-out the whole time.

Much like his DIY generator interlock plate that we covered last month, we imagine this project may rub some folks in the wrong way. Admittedly, this isn’t a modification that you should take lightly and certainly not something you’d want to rely on for long-term use. But as the recent situation in Texas has reminded us, drastic times can occasionally call for drastic measures.

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Air Cannon Serves Up A Blast Of Ferrocerium Sparks

October 15, 2020 by Dan Maloney 25 Comments

OK, looks like we have a new way to entertain the kids and wreak havoc in the neighborhood, if this spark-shooting ferrocerium cannon is as easy to build as it looks.

This one comes to us by well-known purveyor of eyebrow-singing projects [NightHawkInLight], whose propane torch never seems to get a break. The idea here is a large scale version of an apparently popular trick where the “flints” from lighters, which are actually rods of ferrocerium, an aptly named alloy of iron and cerium, are heated to a nearly molten state and dropped onto a hard surface. The molten alloy thence explodes in a shower of sparks, to the mirth and merriment of those in attendance.

[NightHawkInLight]’s version of the trick scales everything up. Rather than lighter flints, he uses ferrocerium rods from firestarters of the type used for camping. The rod is stuffed into a barrel formed from steel brake line which is connected to the output of a PVC air chamber. His ominpresent propane torch is attached in such a way as the flame plays upon the loaded pyrophoric plug, heating it to a molten state before the air is released from the chamber. The massive display of sparks seen in the video below is pretty impressive, but we’re getting tired of gender reveal parties and forest fires. We just hope he had fire extinguishers on hand.

Seriously, be careful with stuff like this. [NightHawkInLight] has a lot of experience working with these kinds of projects, from his plasma-propelled soda bottles to making synthetic rubies with an arc welder. We’re sure he wouldn’t want to see anyone get hurt.

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Fire Pit Burns To The Beat With Bluetooth

August 20, 2020 by Al Williams 3 Comments

Humans have several primal fascinations and perhaps two of the biggest ones are fire and music. While you can picture some cavemen and cavewomen sitting around a fire beating on sticks for rhythm, we think they’d be impressed if the fire danced along with the music. Through the power of Bluetooth, that’s exactly what [Random Tech DIY’s] new fire pit does.

Technically, this is called a Rubens tube, and while it’s an old technology, the Bluetooth is a certainly a modern touch. As you might expect, most of this project is workshop time, cutting MDF and plastic. The audio system is off-the-shelf and drives some car stereo speakers. The results looked good, and although it always makes us nervous building things that carry propane gas, it seems to work well enough from where we’re sitting.

We had to wonder what things you could change that would affect the display. Changing the number of holes, the diameter of the holes, or the gas pressure, for example, would certainly change how the flames look and react to the sound waves.

We have seen other Rubens tube projects, of course. However, we were really interested in the use of these as crude oscilloscopes before the availability of cathode ray tubes. We’ve seen a modern take on that, too.

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BBQ Burners Built From Scratch

February 13, 2020 by Lewin Day 23 Comments

Building a barbecue is a common DIY pursuit, and one that comes with a tasty payoff at completion. While many projects focus on charcoal or wood-fired designs, [Andrew] is more of a gas man. Not one to simply buy off the shelf, he designed his own burners from scratch.

This quest wasn’t just unnecessary yak shaving; burners to suit [Andrew]’s desired size and power simply weren’t available. The burner is designed around the Venturi effect, wherein the propane gas is passed through a small orifice, creating a jet and pulling air along with it as it enters the burner tube. This causes the gases to mix, and they can then be ignited when passing through the outlet holes of the burner. Get the orifice and outlet holes sized just right, and you’ll have a burner that produces a hot, blue flame, perfect for efficient cooking.

The orifice was produced with brass plumbing components, and hooked up to a valve rated for use with gas lines. The burner tube itself was created from stainless steel tube, with slots cut to act as outlet holes and with the end crimped and welded shut. A black iron pipe reducer was then used as the air inlet and orifice mount.

The final result is a powerful barbecue burner that is perfectly sized to [Andrew]’s needs. If you’re keen to build your own custom rig, you may find this a useful and cheap way to go versus sourcing parts off the shelf. We’ve seen [Andrew]’s work before, too. Video after the break.

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