3D Printing Metal from Rust

It seems backwards, but engineers from Northwestern University have made 3D printing metal easier (and eventually cheaper) by adding extra production steps to the procedure. (Paper available in PDF).

Laser sintering works by laying down a thin layer of metal powder and then hitting it with a strong enough laser to sinter the particles together. (Sintering sticks the grains together without getting the metal hot enough to melt it.) The rapid local heating and cooling required to build up 3D objects expands and cools the metal, and can result in stresses inside the resulting object.

The Northwestern team still lays down layers of powder, but glues the layers together with a quick-drying polymer instead of fusing them with a laser. Once the full model is printed, they then sinter it in one piece in an oven.

3D-printed copper lattice. Credit: Ramille Shah and David Dunand

The advantages of adding this extra step are higher printing speed — squirting the liquid out of syringe heads can be faster than fusing metal particles with a laser — and increased structural integrity because the whole model is heated and cooled at one time. A fringe benefit is that the model is still a bit flexible before firing, opening up possibilities for printing a flat model and then bending it into shape before sintering.

And if that weren’t enough, the team figured that they’d add a third step to the procedure to allow it to be used with rust (iron oxide) as the starting powder. They print the rust and polymer model, then un-rust the iron using hydrogen, and then fire it as before. Why rust? Do you know anything cheaper to use as a raw material?

What do you think? The basic idea may even be DIYable — glue metal particles together and heat them up enough to stick. Not in my microwave oven, though. We’d love to see a more energy-efficient 3D metal printer.

Thanks to [Joe] for the tip!

Turning A Laser Cutter Into A 3D Printer With OpenSLS


[Andreas Bastian] has been working on a device that turns an off-the-shelf laser cutter into something capable of selective laser sintering of powdered plastics into 3D objects. He’s put in a lot of work, but now he gets to see the fruits of his labor: he’s successfully printed a few objects out of wax and powdered nylon.

Unlike just about every other inexpensive 3D printer, [Andreas]’ design doesn’t rely on either squirting plastic onto a bed or curing liquid resin with UV light. Instead, a fine layer of powder is spread over a build platform and melted with a laser. The melted layer drops down, another layer of powder is applied, and the cycle repeats until the part is finished. It’s a challenge to build one of these machines, but [Andreas] had the great idea of retrofitting an off-the-shelf laser cutter, allowing him to focus on the difficult task of designing the powder and piston system.

It’s an extremely interesting project, and most of the custom parts are made from laser cut acrylic: easily cut to size on whatever laser cutter you’re retrofitting with 3D printing capability. There’s a lot of info over on the Wiki, and a few videos showing the sintering process and powder distribution below.

Oh. One last note. [Andreas] developed this while at [Jordan Miller]’s amazing lab at Rice University. There’s a lot of interesting things happening at this Advanced Manufacturing Research Institute, including bioprinting, DLP resin printers, and using inkjets for cell cultures. Check out this post for a great talk at the Midwest RepRap Festival.

Continue reading “Turning A Laser Cutter Into A 3D Printer With OpenSLS”

3D Printed Guitar

We’re not sure how we missed this one, but it definitely deserves a look. Professor of Mechtronics [Olaf Diegel’s] 3D printer must go to 12, because he’s printed these incredible electric guitar bodies. You probably won’t be making your own on your filament printer, however, because [Diegel] uses SLS (Selective Laser Sintering) to create the body out of nylon, then he dyes the resulting piece in a two-step process. You can read more about the construction specifics on his website.

And, they’re more than just eye-candy: the guitars sound brilliantly metallic. There are more than enough pictures and videos to keep you occupied on the site, where you can sift through all eight designs to your heart’s content. You’ll want to keep reading for a couple of videos embedded after the break, which feature some demonstrations of the guitar and comparisons to traditional electric guitars, as well as a brief history of its construction and build process.

Continue reading “3D Printed Guitar”

NASA is 3D printing rocket engine parts

In case you haven’t heard, NASA is building a new rocket – a replacement for the shuttle – that will eventually take crews again outside low Earth orbit. It’s called the Space Launch System and looks surprisingly similar to the Saturn V that took men to the moon. Manufacturing technology is light years ahead of what it was in the mid-60s, and this time around NASA is printing some rocket parts with selective laser melting.

Teams at the Marshall Space Flight center are melting metal powder together with lasers to produce parts for the new J-2X engine intended for use in the earth departure stage of the Space Launch System. While the 3d-printed parts haven’t seen a use in any live fire tests of the J-2X, the goal is to test these parts out later in the year and eventually have them man-rated, to carry astronauts to the moon, asteroids, or even Mars.

This isn’t the first time 3d printing has been used to make rocket engines. Earlier this year we saw [Rocket Moonlighting] build an entire rocket engine, powered by propane and NO2, using the same technology that NASA is using. [Moonlighting]’s engine is quite small, too small to lift itself off the ground, even. Still, it’s awesome to see 3D printing that will eventually take people into solar orbit.

A 3D Printed Aerial Drone

Drones come in many shapes and sizes, but now they can also be 3d printed! To make these drones, the [Decode] group used a selective laser sintering process which is pretty interesting in itself. Once the printing process is done, these little planes are built with only five structural and aerodynamic components. Because of their simplicity, these drones can reportedly be assembled and ready to fly with no tools in only ten minutes!

This design was done by the [Engineering and Physical Sciences Research Council] at the University of Southampton in the UK by a group of students. Besides this particular plane, they concentrate their efforts on building autonomous drones under 20 Kilograms. Using a 3D sintering process with this design allowed them to make this plane how they wanted, regardless of the ease of machining the parts.

This group has several videos of their planes on their website to download, but check after the break for an embedded video of the [Newscientist] piece about their project. Continue reading “A 3D Printed Aerial Drone”

CNC build ditches rods for hardboard

This is a redesigned x-axis for [Peter Jansen’s] selective laser sintering rig. We looked in on his SLS project last month and since then he’s been refining the design. The new component uses a rack and pinion system, relying on some Kapton tape to reduce friction for a nice smooth slide. One stepper motor powers the laser-cut gear box with four gears interfacing the sled to the frame for stable and accurate motion. Now he’s just got to work out the math/physics that go into finding the optimal gear ratios as this prototype is just a rough guess. If you’ve got the skills to work it out please lend [Peter] a hand as we’re quite excited with where this is going.

Selective Laser Sintering rig on the cheap

[Peter’s] been hard at work designing an affordable Selective Laser Sintering (SLS) 3D printing platform. We first saw his work on this back in April when he was working mostly with acrylic. Now he’s moved on to a design that relies on hardboard which has resulted in a build that comes it at around $20 including the motors.

The design uses a dual z-axis table for the feed stage and the build stage. That is to say, as the powder is fused together by the laser the platform it is on is lowered. Next to this platform, the feed platform is raised, allowing the power to be swept onto the build stage. This setup is moving in the right direction, but we’re still waiting to see what works when it comes to adding the laser and sourcing the powder.