No, Your 3D Printer Doesn’t Have A Fingerprint

March 12, 2019 by Tom Nardi 103 Comments

Hackers and makers see the desktop 3D printer as something close to a dream come true, a device that enables automated small-scale manufacturing for a few hundred dollars. But it’s not unreasonable to say that most of us are idealists; we see the rise of 3D printing as a positive development because we have positive intentions for the technology. But what of those who would use 3D printers to produce objects of more questionable intent?

We’ve already seen 3D printed credit card skimmers in the wild, and if you have a clear enough picture of a key its been demonstrated that you can print a functional copy. Following this logic, it’s reasonable to conclude that the forensic identification of 3D printed objects could one day become a valuable tool for law enforcement. If a printed credit card skimmer is recovered by authorities, being able to tell how and when it was printed could provide valuable clues as to who put it there.

This precise line of thinking is how the paper “PrinTracker: Fingerprinting 3D Printers using Commodity Scanners” (PDF link) came to be. This research, led by the University at Buffalo, aims to develop a system which would allow investigators to scan a 3D printed object recovered from a crime scene and identify which printer was used to produce it. The document claims that microscopic inconsistencies in the object are distinctive enough that they’re analogous to the human fingerprint.

But like many of you, I had considerable doubts about this proposal when it was recently featured here on Hackaday. Those of us who use 3D printers on a regular basis know how many variables are involved in getting consistent prints, and how introducing even the smallest change can have a huge impact on the final product. The idea that a visual inspection could make any useful identification with all of these parameters in play was exceptionally difficult to believe.

In light of my own doubts, and some of the excellent points brought up by reader comments, I thought a closer examination of the PrinTracker concept was in order. How exactly is this identification system supposed to work? How well does it adapt to the highly dynamic nature of 3D printing? But perhaps most importantly, could these techniques really be trusted in a criminal investigation?

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OpenSCAD Gives You Parametric Boxes

March 11, 2019 by Brian Benchoff 39 Comments

OpenSCAD is one of the most powerful 3d modeling applications around. Its beauty is in its simplicity; if you need a box, you can just write the code for a box. If you need some bit of plastic to keep your 3D printer running, you can just write the code for that bit of plastic. Like all programming languages, OpenSCAD is only really powerful if you have a huge back-catalog of various components ready for reuse. That’s where [Mark]’s library for hinged boxes comes in handy. Every type of box you would ever want to create, from boxes with covers, magnet closures, or cases for your glasses is easily accessible with just a few lines of code.

The work presented here is an OpenSCAD script to generate two-piece hinged boxes, with rounded corners, a lid, interlocking rims, and optional snap fit, magnet, or screw closures. As you would expect from OpenSCAD, everything in this script is parametric. You can change any measurement or simply delete entire sections of the box.

The included examples consist of a small mini-Altoids tin-sized ‘Bee Box’ with a snap-fit lid. All of the relevant dimensions of the snap-fit lid are variables. Other examples include an eyeglass case and a box for small parts storage that interlock. If you have a few rolls of filament, a lot of time on your hands, and want to organize your workbench, you could do worse than checking out a few of these OpenSCAD boxes.

3D Printing Photos Is Slow But Awesome

March 5, 2019 by Lewin Day 13 Comments

Historically speaking, lithophanes are images made in porcelain with an etching or moulding process, in which an image is visible when backlit due to the varying thickness of the material. Porcelain isn’t the easiest thing to work with, but thankfully for those of us in the present, 3D printers are here to make everything better. [RCLifeOn] has been experimenting with printing lithophanes with great results.

The trick to printing a good lithophane is all in the preparation. It’s important to pick an image that looks good in greyscale, as this is not a process that reproduces color in any way. [RCLifeOn] then discusses the finer points of printer setup to get a nice looking print. Layer heights should be as small as possible to avoid visible vertical bands, and the lithophane should be printed in a vertical orientation, to avoid the print sagging due to a lack of support. Infill is best set to 100%. Most importantly, the printer should avoid crossing the outline of the print to avoid any stringy plastic artifacts spoiling the final product.

It’s a great guide that should help even a 3D printing novice create a great print with the minimum of fuss. A lithophane can make a wonderful gift and is also a good test of a printer’s capabilities, due to the fine detail required. We’ve seen them produced before too, in a wonderful lightbox configuration. Video after the break.

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Forget The Kiln, These Tiles Were Made On A Prusa

March 5, 2019 by Tom Nardi 22 Comments

Where does your mind go when you think of 3D printed parts? Running off hard to find replacement components? Maybe spinning up a bespoke electronics enclosure? Occasionally the little boat that you can compare to the little boats of others online? All reasonable enough answers. But thanks to the work of [Matthew Wentworth], you might have a new mental image to associate with the smell of melting PLA: decorative Portuguese Azulejo tiles.

As difficult as it might be to believe, the tiles you’re seeing here weren’t made on some exotic ceramic printer, but a standard Prusa i3 MK3. Well, at least they started on the 3D printer. As you might have guessed, there’s a bit more involved than that.

That said, the idea is actually quite simple. The printed “tile” is just the base plate, plus the raised elements that will eventually be seen on the surface. Everything else is just a void, which naturally saves a lot on printing time and material. Once the print is done, premixed spackling paste is pushed into all of the open areas and the top is made as smooth as possible with a putty knife. The filled tile is then left to dry for 24 hours or so.

Once it’s dried, you take the tile outside and sand the top down with a palm sander (or by hand, if you have the patience). This not only smooths out the spackle, but eventually will expose and then smooth the top parts of the print. Once everything is nice and silky, it gets sprayed with a semi-gloss clear coat to both protect it and give it that authentic looking shine.

[Matthew] actually created his designs based on images of real Azulejo tiles he found online, but really any sort of image that has raised elements like this could be made to work. If anyone out there decorates their home with 3D printed Jolly Wrencher tiles, you know where to send the pictures. Interestingly, these aren’t the first tiles we’ve seen made out of plastic, but we’ve got to admit these ones would look quite a bit more appealing on your kitchen walls.

PrintRite Uses TensorFlow To Avoid Printing Catastrophies

March 3, 2019 by Lewin Day 14 Comments

TensorFlow is a popular machine learning package, that among other things, is particularly adept at image recognition. If you want to use a webcam to monitor cats on your lawn or alert you to visitors, TensorFlow can help you achieve this with a bunch of pre-baked libraries. [Eric] took a different tack with PrintRite – using TensorFlow to monitor his 3D printer and warn him of prints gone bad – or worse.

The project relies on training TensorFlow to recognize images of 3D prints gone bad. If layers are separated, or the nozzle is covered in melted goo, it’s probably a good idea to stop the print. Worst case, your printer could begin smoking or catch fire – in that case, [Eric] has the system configured to shut the printer off using a TP-Link Wi-Fi enabled power socket.

Currently, the project exists as a plugin for OctoPrint and relies on two Raspberry Pis – a Zero to handle the camera, and a 3B+to handle OctoPrint and the TensorFlow software. It’s in an early stage of development and is likely not quite ready to replace human supervision. Still, this is a project that holds a lot of promise, and we’re eager to see further development in this area.

There’s a lot of development happening to improve the reliability of 3D printers – we’ve even seen a trick device for resuming failed prints.

3D Printing Logic Gates

March 2, 2019 by Al Williams 17 Comments

It may seem a paradox, but in the future tiny computers may dump electronics and return to their mechanical roots. At the macroscale, mechanical computers are fussy and slow, but when your area is down to a few molecules, electronics have trouble working but mechanical systems do just fine. In addition, these devices don’t use electricity directly, don’t generate electronic signatures, and may be less sensitive to things like radiation that damage electronics. A recent paper in Nature Communications discusses how to 3D print common logic gates using both macro-scale 3D printing techniques and a much smaller version with microstereolithography. You can see a video of gates in action below.

The gates use a bistable flexible mechanism. The larger gates use ABS plastic and measure about 250mm square. The smaller gate measures less than 25 mm square. They also use a special technique to make gates as small as 100 microns theoretically possible, although some of that is future work for the team.

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Pack Your SD Cards Swiss Army Style

March 1, 2019 by Lewin Day 19 Comments

SD cards have largely supplanted most other card-based storage devices, in all but a few niches. Available in standard, micro, and the rather obscure mini sizes, they’re used in everything from digital cameras to car stereos and console ROM carts. For most users, storing them consists of tossing them in a bag, occasionally in a plastic case that’s barely any bigger than the card itself for a little extra protection. This can get frustrating when carrying multiple cards, but [Dranoweb] has a solution.

[Dranoweb]’s design is similar to a Swiss Army knife, repurposed with many fingers, each with slots for holding everyone’s favourite storage devices. All the parts barring the screw are 3D printed. There are various designs of the storage fingers, allowing the build to be customized to suit varying quantities of SD and microSD cards. There’s even a deep-pocketed piece for USB drives and small adapters, and an oversized design for Nintendo DS carts.

It’s a tidy design that makes it that much less likely you’ll lose your microSD in the bottom of your backpack. Now, if you need to interface with an SD card, we can help you there too.