3D Printering: To Print Stainless, You Do Half The Work

Everyone wants to print using metal. It is possible, but the machines to do the work are usually quite expensive. So it caught our eye when MakerBot announced a printer — armed with an experimental extruder — that can print stainless steel parts. Then we read a bit more and realized that it can only sort of do the job. It needs a lot of help. And with some reasonable, if not trivial, modifications, your printer can probably print metal as well.

The key part of the system is BASF Ultrafuse 316L Stainless Steel filament, something that’s been around for a few years. This is a polymer with metal incorporated into it. This explains the special extruder, since metal-bearing filament is hell on typical 3D printer nozzles. However, what comes out isn’t really steel — not yet. For that, you have to send the part to a post-processing facility where it is baked at 1380 °C in a pure hydrogen atmosphere using special equipment. This debinding and sintering produces a part that the company claims can be up to 96% pure metal.

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Wearable Sensors On Your Skin

An international team at Penn State led by [Larry Cheng] made a breakthrough in printing sensors directly on skin without heat. The breakthrough here is the development of a room-temperature sintering technique. Typical sintering of copper happens at 300 C, and can be further lowered to 100 C by adding nanoparticles. But even 100 C is too hot, since skin starts to burn at around 40 C.

You can obtain their journal article if you want the details, but basically their technique combines the ingredients in peelable face masks and eggshells. With this printed circuit is applied to the skin, the sintering process only requires a hair dryer on the cool setting, and results can bend and fold without breaking the connections. A hot shower will remove the circuit without damaging the circuit or your skin. [Larry] says the circuits can be recycled.

They are using these sensors to monitor temperature, humidity, blood oxygen levels, and heart performance indicators. They’ve even linked these various on-body sensors with a WiFi network for ease of monitoring. After reading this report, we’re left wondering, if the sensor is directly on your skin, can it be really called wearable?

We’ve written about printable inks before, but for printed circuit board applications.  We can’t help but wonder if this technology would help solve some problems inherent in that technology, as well. Thanks to [Qes] for the tip.

3D Printing Damascus-like Steel

Recreating Damascus steel remains a holy grail of materials science. The exact process and alloys used are long ago lost to time. At best, modern steelworking methods are able to produce a rough visual simulacra of sorts that many still consider to be pretty cool looking. Taking a more serious bent at materials science than your average knifemaker, a group of scientists at the Max Planck institute have been working to create a material with similar properties through 3D printing.

The technology used is based on the laser sintering of metal powders. In this case, the powder consists of a mixture of iron, nickel and titanium. The team found that by varying the exact settings of the laser sintering process on a layer-by-layer basis, they could create different microstructures throughout a single part. This allows the creation of parts that are ductile, while remaining hard enough to be sharpened – a property which is useful in edged weapons like swords.

While the process is nothing like that used by smiths in Damascus working with Wootz steel, the general idea of a metal material with varying properties throughout remains the same. For those eager to get into old-school metalwork, consider our articles on blacksmithing. For those interested in materials research, head to a good university. Or, better yet – do both!

[Thanks to Itay for the tip, via New Atlas]

Sinterit Pulls SLS 3D Printer Entry Level Price Down To Just $8k

Almost exactly two years ago, news of a great revolution in 3D printing carried itself through blogs and tech columns. Patents were expiring, and soon the ‘squirting filament’ printers would be overtaken by a vastly better method: selective laser sintering. In the last two years, the market has been markedly silent on the possibilities of SLS technology, until now, at least. Today, Sinterit is launching their first printer. It’s an SLS printer that builds objects by fusing nylon powder with a laser, producing things with much better quality than filament-based printers.

The Sinterit Lisa is a true laser sintering printer, able to create objects by blasting nylon powder with a 5W laser diode. Inside this box that’s about the same size as a laser printer is a CoreXY mechanism to move the laser diode around, heated pistons, cylinders, feed bed and print bed for keeping the print volume at the right temperature and the top layer perfectly flat. The layer thickness of the printer goes down to 0.06 mm, and the maximum print size is 13 x 17 x 13 cm. Material choice is, for now, limited to black PA12 nylon but other materials are being tested.

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Ester, The Open Source SLS Printer

Filament printers are here to stay, and in the past year there have been a number of SLA and DLP resin printers that can create objects at mind-boggling high resolutions. Both of these technologies have their place, but printing really complex objects without also printing supports is out of the question.

[Brandon] has been working to create an open source printer using a different technology, selective laser sintering. That’s a laser melting tiny particles of stuff to create an object. This printer can work with any material that can be turned into a powder and melted by a laser, and also has the neat bonus of printing without any supports.

[Brandon]’s printer, Ester, uses small meltable polyester dust as both a print material and support structure. The object to be printed is created by shining a laser over a bed filled with polyester, drawing one layer, and putting another small layer of material over the previous layer.

The machine is using a diode laser, with a few experiments with a 1 Watt diode providing some very nice parts. The mechanics of the machine were built at [Brandon]’s local TechShop, and already he has an IndieGoGo for future development and a $3000 development kit. That’s a bit expensive as far as project printers go, but SLS is an expensive technology to get right; ‘pro’ SLS printers are in the hundreds of thousands of dollars.

Pwdr, The Open Source Powder Printer

Meet pwdr, the open source 3D printer that is a complete departure from the RepRaps and Makerbots we’ve come to love.

Instead of squirting plastic onto a build surface, pwdr operates just like the very, very expensive powder printers used in industrial settings. Pwdr uses gypsum, ceramics, and concrete for its raw stock and binds these powder granules together with water deposited from an inkjet cartridge.

Inside pwdr there are two bins, one for storing the raw material and another for building the part. The part to be printed is built one layer at a time, just like your regular desktop printer. After each layer is finished, a counter-rotating drum scrapes the raw material over the build area and another layer is printed.

There are a lot of advantages to pwdr versus the melted plastic method of printing used in the Makerbot; because each build is self-supporting, it’s possible to print objects that just couldn’t be made with an extruder-based printer. Pwdr also supports laser sintering, meaning it’s possible for pwdr to make objects out of ABS, Nylon, and even metal.

Right now, pwdr is still in the very early stages of development, but you can build your own powder printer from the files up on Thingiverse. Check out the video of pwdr printing after the break.

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Selective Solar Sintering With Sand

[Markus Kayser] built an amazing solar powered SLS printer, but instead of using lasers and powdered plastics his machine uses the power of the sun to heat sand into complex shapes.

[Markus]’ printer uses the same concept as his earlier solar cutter – burning things with a magnifying glass. Interestingly, the printer isn’t controlled with stepper motors and reprap electronics – it’s completely cam driven. The solar panels only power the motor attached to the frame moving on bearings made from skateboard wheels.

We’d guess that [Markus] is using a little more than 2 square meters of Fresnel lenses in his project. Since solar irradiance is about 120 W/m² (PDF warning), [Markus] is concentrating a lot of energy onto a point the size of a quarter, which would be necessary to heat up sand to its 1500° C melting point. The resolution isn’t what you could get with a laser, but [Markus] was able to print an amazing bowl along with other complex 3d shapes.

Check out [Markus]’ video of the solar sinter printer after the break. There’s also a video of his previous experiment with the solar cutter.

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