Cold Metal Fusion For 3D Printing

When you see the term cold fusion, you probably think about energy generation, but the Cold Metal Fusion Alliance is an industry group all about 3D printing metal using Selective Laser Sintering (SLS) printers. The technology promoted by Headmade Materials typically involves using a mix of metal and plastic powder. The resulting part is tougher than you might expect, allowing you to perform mechanical operations on it before it is oven-sintered to remove the plastic.

The key appears to be the patented powder, where each metal particle has a thin polymer coating. The low temperature of the laser in the SLS machine melts the polymer, binding the metal particles together. After printing, a chemical debinding system prepares the part — which takes twelve hours. Then, you need another twelve hours in the oven to get the actual metal part.

You might wonder why we are interested in this. After all, SLS printers are unusual — but not unheard of — in home labs. But we were looking at the latest offerings from Nexa3D and realized that the lasers in their low-end machines are not far from the lasers we have in our shops today. The QLS230, for example, operates at 30 watts. There’s plenty of people reading this that have cutters in that range or beyond out in the garage or basement.

We aren’t sure what a hobby setup would look like for the debinding and the oven steps, but it can’t be that hard. Maybe it is time to look at homebrew SLS printers again. Of course, the powder isn’t cheap and is probably hard to replace. We saw a 20 kg tub of it for the low price of €5,000. On the other hand, that’s a lot of powder, and it looks like whatever doesn’t go into your part can be reused so the price isn’t as bad as it sounds. We’d love to see someone get some of this and try it with a hacked printer.

We have seen homebrew SLS printers. There’s also OpenSLS that, coincidentally, uses a laser cutter. It wouldn’t be cheap or easy, but being able to turn out metal parts in your garage would be quite the payoff. Be sure to keep us posted on your progress.

Learning 3D Printing Best Practices From A Pro

It might seem like 3D printing is a thoroughly modern technology, but the fact is, it’s been used in the industry for decades. The only thing that’s really new is that the printers have become cheap and small enough for folks like us to buy one and plop it on our workbench. So why not take advantage of all that knowledge accumulated by those who’ve been working in the 3D printing field, more accurately referred to as additive manufacturing, since before MakerBot stopped making wooden printers?

That’s why we asked Eric Utley, an applications engineer with Protolabs, to stop by the Hack Chat this week. With over 15 years of experience in additive manufacturing, it’s fair to say he’s seen the technology go through some pretty big changes. Hes worked on everything from the classic stereolithography (SLA) to the newer Multi Jet Fusion (MJF) printers, with a recent focus on printing in metals such as Inconel and aluminum. Compared to the sort of 3D printers he’s worked with, we’re basically playing with hot, semi-melted, LEGOs — but that doesn’t mean some of the lessons he’s learned can’t be applied at the hobbyist level. Continue reading “Learning 3D Printing Best Practices From A Pro”

Dyson Hair Dryer Becomes Jet Engine

While Dyson makes some good products, they aren’t known for being economical. Case in point: [Integza] spent $500 on a hair dryer. While he does have a fine head of hair, we suspected he wasn’t after it for its intended purpose, and we were right. It turns out he wanted to make it into a jet engine! Why? Oh, come on. The fact that you read Hackaday means you don’t need that question answered. Watch the video below to see how it all turned out.

What got [Integza]’s attention was the power of the very small motor. So he immediately, of course, opened it up. The build quality is very impressive, although for $500, shouldn’t it be? While we are sure the Dyson dryer is more robust than our $9 Revlon special, it seems doubtful that it would handle the high temperatures of a jet exhaust. In fact, he’s had plastic meltdown while trying to build a jet before. So this time, he had a different plan.

That plan involved designing a replacement shell for the dryer and having it 3D printed in metal, which may have cost almost as much or more than the dryer. It came out great, though — and some fuel lines and a spark plug later, he was ready to fire it up.

Did it work? You bet. Test equipment was melted accidentally, and eventually, the engine looked like it flamed out. But it generated some very hot exhaust. We’d like to say that no tomatoes were harmed during the production of the video, but we can’t because of our well-developed sense of ethics. Poor tomatoes! We might have used a Mr. Bill doll, but that probably infringes on someone’s copyright.

If you don’t want so much melting, maybe try water cooling. If you could make this reliable, the modification to your car becomes obvious.

Continue reading “Dyson Hair Dryer Becomes Jet Engine”

Microscopic Metal 3D Printing With Gels

Everyone wants to 3D print with metals, but it is a difficult task. You need high temperatures and metals with high thermal conductivity make the problem even worse. Researchers at Caltech have a way of printing tiny metal structures. The trick? They don’t print metals at all. Instead, they 3D print a hydrogel and then use it as a scaffold to form metallic structures. You can read the full paper, if you are interested in the details.

Hydrogels are insoluble in water and made from flexible polymer chains. If you’ve ever handled a soft contact lens, that’s a hydrogel. Like resin printing, UV light triggers chemical reactions in the hydrogels, causing them to harden in the desired pattern.

What about the metal? They infuse the hydrogel with a metallic salt dissolved in water.  This saturates the hydrogel. Burning in a furnace causes the hydrogel to burn away but leaves the metal. The furnace also causes the structure to shrink, so this is a good method for very tiny pieces. The team has made prints with feature sizes around 40 microns.

By altering the metal salts, you can work with different metals or even mix different metals. The team has produced parts using copper, nickel, silver, and several alloys.

Printing small structures is a big research goal with many different approaches. We’ve even seen a tiny welder.

3D Printed Heat Exchanger Uses Gyroid Infill For Cooling

3D printing allows the physical manufacturing of some unique geometries that are simply not possible with other processes. If you design around these strengths, it is possible to create parts that significantly outperform more conventional alternatives. With this in mind [Advanced Engineering Solutions] created a metal 3D printed heat exchanger that is half the size and four times the efficiency of the one it was designed to replace. Video after the break.

Gyroid infill splits an internal volume in two, perfect for heat exchangers.

Made from an aluminum alloy using a Laser Powder Bed Fusion (LPBF) machine, the heat exchanger is intended to cool transmission oil on military helicopters by using fuel as the coolant. Looking somewhat similar to a Fabergé egg, it uses gyroid “infill” for the actual heat exchange part. An interesting characteristic of gyroids is that it creates two separate intermeshed volumes, making them perfect for this application.

It was printed in one piece, without any removable support, just an internal lattice that supports the gyroids at the inlet and outlets. The only post-processing required was threading and surface cleanup on the ports. Since metal 3D printing is still too expensive to really allow many iterative prints, a significant amount of design and simulation time was put in before the first print.

Continue reading “3D Printed Heat Exchanger Uses Gyroid Infill For Cooling”

3D Printing A Check Valve In Metal

[SunShine] has been working on 3D printed pumps and similar parts with an aim towards building smaller and more compact hydraulic systems. His latest effort involves printing working hydraulic check valves that can be integrated seamlessly into his designs. 

Unlike many 3D printing enthusiasts, [SunShine] works with metal printers of the laser powder bed type. His expectations for his parts are thus very high, and he aimed to create check valves that could withstand high hydraulic pressures.

After much work, [SunShine] came up with two designs for 3D-printed check valves that would work. However, they both needed internal removal of support structures that couldn’t be achieved without cutting them open. He then figured out that he could use a special process using nitric acid to carefully eat away a very precise amount of metal inside the valves, which would remove the support material without destroying the whole valve itself.

While the valves couldn’t be tested beyond 400 bar due to the available equipment, they did work as intended. As a bonus, they actually sealed better as they were used more, as the sealing surfaces bedded in and deformed to match each other.

The video is then rounded out with a simple plastic check valve design you can print at home. It reminds us of other valves we’ve seen created with 3D printing before. Video after the break.

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Hackaday Links: April 10, 2022

A funny thing happened on the way to the delta. The one on Jezero crater on Mars, that is, as the Perseverance rover may have captured a glimpse of the parachute that helped deliver it to the Red Planet a little over a year ago. Getting the rover safely onto the Martian surface was an incredibly complex undertaking, made all the more impressive by the fact that it was completely autonomous. The parachute, which slowed the descent vehicle holding the rover, was jettisoned well before the “Sky Crane” deployed to lower the rover to the surface. The parachute wafted to the surface a bit over a kilometer from the landing zone. NASA hasn’t confirmed that what’s seen in the raw images is the chute; in fact, they haven’t even acknowledged the big white thing that’s obviously not a rock in the picture at all. Perhaps they’re reserving final judgment until they get an overflight by the Ingenuity helicopter, which is currently landed not too far from where the descent stage crashed. We’d love to see pictures of that wreckage.

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