Fooling Fingerprint Scanners With A Resin Printer

April 8, 2019 by Lewin Day 12 Comments

Biometrics have often been used as a form of access control. While this was initially limited to bank vaults in Hollywood movies, it’s now common to see such features on many laptops and smartphones. Despite the laundry list of reasons why this is a bad idea, the technology continues to grow in popularity. [darkshark] has shown us an easy exploit, using a 3D printer to fool the Galaxy S10’s fingerprint scanner.

The Galaxy S10 is interesting for its use of an ultrasonic fingerprint sensor, which continues to push to hardware development of phones minimal-to-no bezels by placing the sensor below the screen. The sensor is looking for the depth of the ridges of your fingerprint, while the touchscreen verifies the capacitive presence of your meaty digit. This hack satisfies both of those checks.

[darkshark] starts with a photograph of a fingerprint on a wineglass. This is then manipulated in Photoshop, before being used to create geometry in 3DSMAX to replicate the original finger. After making the part on an AnyCubic Photon LCD resin printer, the faux-finger pad is able to successfully unlock the phone by placing the print on the glass and touching your finger on top of it.ster

[darkshark] notes that the fingerprint was harvested at close range, but a camera with the right lenses could capture similar detail at a distance. The other thing to note is that if your phone is stolen, it’s likely covered in greasy fingerprints anyway. As usual, it serves as an excellent reminder that fingerprints are not passwords, and should not be treated as such. If you need to brush up on the fundamentals, we’ve got a great primer on how fingerprint scanners work, and another on why using fingerprints for security is a bad plan.

[via reddit, thanks to TheEngineer for the tip!]

3D Printing With Tomography In Reverse

February 5, 2019 by Lewin Day 33 Comments

The 3D printers we’re most familiar with use the fused deposition process, in which hot plastic is squirted out of a nozzle, to build up parts on a layer by layer basis. We’ve also seen stereolithography printers, such as the Form 2, which use a projector and a special resin to produce parts, again in a layer-by-layer method. However, a team from the University of North Carolina were inspired by CT scanners, and came up with a novel method for producing 3D printed parts.

The process, as outlined in the team’s paper.

The technique is known as Computed Axial Lithography. The team describe the system as working like a CT scan in reverse. The 3D model geometry is created, and then a series of 2D images are created by rotating the part about the vertical axis. These 2D images are then projected into a cylindrical container of photosensitive resin, which rotates during the process. Rather than building the part out of a series of layers in the Z-axis, instead the part is built from a series of axial slices as the cylinder rotates.

The parts produced have the benefit of a smooth surface finish and are remarkably transparent. The team printed a variety of test objects, including a replica of the famous Thinker sculpture, as well as a replica of a human jaw. Particularly interesting is the capability to make prints which enclose existing objects, demonstrated with a screwdriver handle enclosing the existing steel shank.

It’s a technique which could likely be reproduced by resourceful makers, assuming the correct resin isn’t too hard to come by. The resin market is hotting up, with Prusa announcing new products at a recent Makerfaire. We’re excited to see what comes next, particularly as the high cost of resin is reduced by economies of scale. Video after the break.

[via Nature, thanks to Philip for the tip!]

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Prusa Introduces A Resin Printer At Maker Faire NY

September 22, 2018 by Brian Benchoff 35 Comments

For one reason or another, the World Maker Faire in New York has become the preeminent place to launch 3D printers. MakerBot did it with the Thing-O-Matic way back when, and over the years we’ve seen some interesting new advances come out of Queens during one special weekend in September.

Today Prusa Research announced their latest creation. It’s the resin printer you’ve all been waiting for. The Prusa SL1 is aiming to become the Prusa Mk 3 of the resin printer world: it’s a solid printer, it’s relatively cheap (kit price starts at $1299/€1299), and it produces prints that are at least as good as resin printers that cost three times as much.

The tech inside the SL1 is about what you’d expect if you’ve been following resin printers for a while. The resin is activated by a bank of LEDs shining through a photomask, in this case a 5.5 inch, 1440p display. Everything is printed on a removable bed that can be transferred over to a separate ‘curing chamber’ after the print is done. It’s more or less what you would expect, but there are some fascinating refinements to the design that make this a resin printer worthy of carrying the Prusa name.

Common problems with a masked SLA printer that uses LEDs and an LCD are the interface between the LCD and the resin, and the temperature of the display itself. Resin is not kind to LCD displays, and to remedy this problem, Prusa has included an FEP film on the bottom of the removable tank. This is a user-replaceable part (technically a consumable, at least to the same extent as a PEI build plate on a filament printer), and Prusa will be selling those as spare parts on their store. The LCD is also cooled; one of the major drawbacks of shining several watts of UV through an LCD is the lifetime of the display. Cooling the display helps, and should greatly increase the lifetime of the printer. All of this is wrapped up in an exceptionally heavy metal case with the lovely hinged UV-opaque orange plastic lid.

Of course, saying you’ve built a resin printer is one thing, but how do the prints look? Exceptional. The Prusa booth at Maker Faire was loaded up with sample prints from the machine, and they’re of the same high quality you would expect from the Form 3D printers that have been the go-to in the resin printer world. The Prusa SLA also works with big-O Open resins, meaning you’re not tied to a single resin vendor.

This is just the announcement of the Prusa resin printer, but they are taking preorders. The price for the kit — no word on how complex of a kit it is — is $1300, while the assembled printer is $1600, with the first units shipping in January.

Casting Metal Directly Into 3D Printed Molds

August 27, 2017 by Brian Benchoff 24 Comments

Casting metal and 3D printing go together like nuts and gum, and there are no shortage techniques that use the two together. Lost PLA casting is common, and sculptors are getting turned on to creating their works in plastic first before sending it off to the foundry. Now the folks at FormLabs have turned the whole ‘casting metal and 3D printer’ thing on its head: they’re printing sacrificial molds to cast pewter.

There are two techniques demonstrated in this tutorial, but the real winner here is printing a complete sacrificial mold for pewter miniatures. While this technique requires a little bit of work including washing, curing, and a bit of post-processing, you would have to do that anyway with anything coming out of a resin printer.

The material of choice for these molds is a high temp resin with a heat deflection temperature of 289 °C. Using a pewter alloy that melts at 260 °C, casting a metal miniature is as simple as pouring molten metal into a mold. Demolding might be a little finicky, but with a small screwdriver used as a chisel, it’s possible to get the cast newly parts out.

We’ve seen pewter casting with PLA, but the quality available from the Form resin printers is truly amazing and produces some great looking miniatures.

CES2017: Monoprice Unveils Expanded Line Of 3D Printers

January 7, 2017 by Brian Benchoff 40 Comments

At CES last year, Monoprice introduced a $200 3D printer. Initial expectations of this printer were middling. My curiosity got the best of me, and last summer I picked up one of these printers for a review. The Monoprice MP Select Mini is actually phenomenal, and not just ‘phenomenal for the price’. This machine showed the world how good one of the cheapest printers can be. The future is looking awesome.

You might think Monoprice wouldn’t be able to top the success of this great little machine. You would be wrong. This week, Monoprice announced a bevy of new and upgraded printers. Some are resin. Some are huge. One will sell for $150 USD.

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CES2017: Really, Really Big SLA Printing

January 7, 2017 by Brian Benchoff 13 Comments

Last year at CES, UniZ introduced the Slash, a desktop resin printer. It’s fast, it’s capable, and it’s shipping now, but there was something else in the UniZ booth that had a much bigger wow factor.

The UniZ zSLTV is a gigantic box, a little more than one meter wide, and a little less than one meter tall and deep. Open the lid, and you see a gigantic resin printer turned on its side. The idea here is to fill a gigantic tank with resin, (the build volume is 521 x 293 x 600 mm) and use it as a fairly standard UV LED / LCD resin printer. The only real difference between this machine and any other resin printer is that the part is always submerged in resin.

It’s something we’ve never seen before, and it will be available ‘soon’. The price for this huge machine is in the ballpark of $10,000.

3D Printering: Smartphone Resin Printers Actually Work

November 18, 2016 by Brian Benchoff 51 Comments

Last spring, the world saw something amazing. It was a device that would revolutionize the planet, save the world, and turn your smartphone into a 3D printer. Kickstarters aren’t known for selling themselves short. I speak, of course, of the OLO 3D printer, later renamed the ONO 3D printer, ostensibly because of a trademark dispute.

While filament-based 3D printers are extremely capable and slicing software is only getting better, resin-based printers are able to produce prints of nearly unparalleled quality. If you want high-resolution objects and fine detail, a resin printer is the way to go. These resin printers, however, are a bit more expensive than your traditional filament printers. A few hundred dollars will buy you a serviceable i3 clone, and less than a thousand will get you a real Prusa capable of printing in four colors. The premier desktop resin printer, the Form 2 from Form Labs, starts at $3500 USD.
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