Dexterity Hand Is A Configurable Prosthetic Hand

December 14, 2018 by Bryan Cockfield 5 Comments

One of the interesting benefits of the 3D printing revolution is the dramatic increase in availability of prosthetics for people with virtually any need. With a little bit of research, a 3D printer, and some trial and error, virtually anyone can build a prototype prosthetic to fit them specifically rather than spend thousands of dollars for one from a medical professional. [Dominick Scalise] is attempting to flesh out this idea with a prosthetic hand that he hopes will be a useful prosthetic in itself, but also a platform for others to build on or take ideas from.

His hand is explained in great detail in a series of videos on YouTube. The idea that sets this prosthetic apart from others, however, is its impressive configurability while not relying on servos or other electronics to control the device. The wearer would use their other hand to set the dexterity hand up for whatever task they need to perform, and then perform that task. Its versatility is thanks to a unique style of locks and tensioners which allow the hand to be positioned in various ways, and then squeezed to operate the hand. It seems like a skilled user can configure the hand rapidly, although they must have a way to squeeze the hand to operate it, or someone will need to develop an interface of some sort for people without needing to squeeze it.

To that end, the files for making your own hand are available on Thingiverse. [Dominick] hopes that his project will spark some collaboration and development, using this hand as a basis for building other low-cost 3D printed prosthetics. There are many good ideas from this project that could translate well into other areas of prosthetics, and putting it all out there will hopefully spur more growth in this area. We’ve already seen similar-looking hands that have different methods of actuation, and both projects could benefit from sharing ideas with each other.

Thanks to [mmemetea] for the tip!

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MakerBot Moves Away From Makers With New Printer

December 11, 2018 by Tom Nardi 53 Comments

If you’ve been following the desktop 3D printing market for the last couple years, you’re probably aware of the major players right now. Chinese companies like Creality are dominating the entry level market with machines that are priced low enough to border on impulse buys, Prusa Research is iterating on their i3 design and bringing many exciting new features to the mid-range price point, and Ultimaker remains a solid choice for a high-end workhorse if you’ve got the cash. But one name that is conspicuously absent from a “Who’s Who” of 3D printing manufacturers is MakerBot; despite effectively creating the desktop 3D printing market, today they’ve largely slipped into obscurity.

So when a banner popped up on Thingiverse (MakerBot’s 3D print repository) advertising the imminent announcement of a new printer, there was a general feeling of surprise in the community. It had been assumed for some time that MakerBot was being maintained as a zombie company after being bought by industrial 3D printer manufacturer Stratasys in 2013; essentially using the name as a cheap way to maintain a foothold in the consumer 3D printer market. The idea that they would actually release a new consumer 3D printer in a market that’s already saturated with well-known, agile companies seemed difficult to believe.

But now that MakerBot has officially taken the wraps off a printer model they call Method, it all makes sense. Put simply, this isn’t a printer for us. With Method, MakerBot has officially stepped away from the maker community from which it got its name. While it could be argued that their later model Replicator printers were already edging out of the consumer market based on price alone, the Method makes the transition clear not only from its eye watering $6,500 USD price tag, but with its feature set and design.

That said, it’s still an interesting piece of equipment worth taking a closer look at. It borrows concepts from a number of other companies and printers while introducing a few legitimately compelling features of its own. While the Method might not be on any Hackaday reader’s holiday wish list, we can’t help but be intrigued about the machine’s future.

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True Transparent Parts From A Desktop 3D Printer

December 11, 2018 by Tom Nardi 14 Comments

We’re no strangers to seeing translucent 3D printed parts: if you print in a clear filament with thin enough walls you can sorta see through the resulting parts. It’s not perfect, but if you’re trying to make a lamp shade or decorative object, it’s good enough. You certainly couldn’t print anything practical like viewing windows or lenses, leaving “clear” 3D printing as more of a novelty than a practical process.

But after months of refining his process, [Tomer Glick] has finally put together his guide for creating transparent prints on a standard desktop FDM machine. It doesn’t even require any special filament, he says it will work on PLA, ABS, or PETG, though for the purposes of this demonstration he’s using the new Prusament ABS. The process requires some specific print settings and some post processing, but the results he’s achieved are well worth jumping though a few hoops.

According to [Tomer] the secret is in the print settings. Essentially, you want the printer to push the layers together far closer than normal, in combination with using a high hotend temperature and 100% infill. The end result (hopefully) is the plastic being laid down by the printer is completely fused with the preceding one, making a print that is more of a literal solid object than we’re used to seeing with FDM printing. In fact, you could argue these settings generate internal structures that are nearly the polar opposite of what you’d see on a normal print.

The downside with these unusual print settings is that the outside of the print is exceptionally rough and ugly (as you might expect when forcing as much plastic together as possible). To expose the clear internals, you’ll need to knock the outsides down with some fairly intense sanding. [Tomer] says he starts with 600 and works his way up to 4000, and even mentions that when you get up to the real high grits you might as well use a piece of cardboard to sand the print because that’s about how rough the sandpaper would be anyway.

[Tomer] goes on to demonstrate a printed laser lens, and even shows how you can recreate the effect of laser-engraved acrylic by intentionally putting voids inside the print in whatever shape you like. It’s a really awesome effect and honestly something we would never have believed came off a standard desktop 3D printer.

In the past we’ve seen specialized filament deliver some fairly translucent parts, but those results still weren’t as good as what [Tomer] is getting with standard filament. We’re very interested in seeing more of this process, and are excited to see what kind of applications hackers can come up with.

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Crawling PCB ‘Bot Is Flexible Where It Counts

December 10, 2018 by Lewin Day 1 Comment

20 years ago, PCB production was expensive and required a multitude of phone calls and emails to a fab with significant minimum order restrictions. Now, it’s cheap and accessible online, which in addition to curtailing the home etching market has created significant new possibilities for home projects. Now that flexible PCBs are also readily available, it’s possible to experiment with some cool concepts – and that’s precisely what [Carl] has been doing.

The aim is to build a walking robot that uses actuators made from flexible PCBs. The flexible PCB is printed with a coil, capable of generating a small magnetic field. This then interacts with a strong permanent magnet, causing the flexible PCB to move when energised.

Initial attempts with four actuators mounted to a 3D printed frame were unsuccessful, but [Carl] has persevered. With a focus on weight saving, the MK II prototype has shown some promise, gently twitching its way across a desk in testing. Future steps will involve building an untethered version. This will replace the 3D printed chassis with a standard fibreglass PCB acting as both control board and the main chassis to minimise weight, similar to PCB quadcopter designs we’ve seen in the past.

We can’t wait to see the next revision, and if you’ve been working on your own walking robots, make sure you let us know.

Easily Deboss Notebooks With A 3D Printed Stamp

December 9, 2018 by Tom Nardi 14 Comments

While it’s arguably a bit closer to the “Arts & Crafts” region of the making spectrum upon which we don’t usually tread on account our l33t sense of superiority, we’ve got to admit that the quick and easy notebook customization demonstrated by [Sean Hodgins] is very compelling. We don’t put ink to dead trees with nearly the frequency we used to, but when we do it might as well be Hemingway-style with a little black Hackaday emblazoned notebook.

As demonstrated in the video after the break, the process starts by designing the stamp in your CAD package of choice. For optimal results [Sean] suggests fairly large capital letters, but with practice you should be able to get into some more creative fonts. Potentially you could even use the logo of your favorite hacking blog, but who are we to dictate what you do?

Whatever you chose, it needs to be mirrored and placed on a relatively thick backing. He recommends a 2 mm thick “plate” with the letters raised on top. You’ll want to print it at a high infill percentage, but even still it shouldn’t take more than 30 minutes or so to run off. Remember there tends to be diminishing returns on infill past 50%, so taking it all the way to 100% is not going to do much but expend more time and plastic.

Once printed, [Sean] hot glues the stamp to a block of wood since putting pressure on the printed piece directly would likely crack it. Then it’s just a matter of getting your notebook, printed stamp, and blocks of wood lined up in to a suitably beefy bench vise. Getting everything aligned is one of those things that easier said than done, so expect to mess up the first couple until you get the hang of it.

When the alignment looks good, crank it down and let it sit for a few minutes. If you’re embossing the design into actual leather, wetting it a bit before putting the pressure on should help. The final effect is understated but undeniably very slick; and with the Holidays rapidly approaching this might be an excellent way to knock out some legitimately thoughtful gifts.

Ultimately the idea here is something of a lightweight version of the 3D printed press break dies used to bend aluminum or the punch and die set used for steel plates. At this point it seems there’s enough evidence to say that 3D printed objects are certainly strong enough (in compression, at least) to put some legitimate work in.

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Better Mechanical Keyboards Through 3D Printing

December 7, 2018 by Brian Benchoff 14 Comments

You’re not cool unless you have a mechanical keyboard. No, you won’t be able to tell if your coworkers don’t like it, because you won’t be able to hear their complaining over the sound of your clack-clack-clacking. You can even go all-in with switch modifications, o-rings, and new springs, or you could use your 3D printer to modify the touch of your wonderful Cherry MX switches. That’s what a few researchers did, and the results are promising.

The ‘problem’ this research is attempting to solve is bottoming out on Cherry MX keyswitches. If you’re bottoming out, you’re doing it wrong, but nevertheless, you can get a publication out of solving repetitive strain injury. This was done by modeling the bottom housing of a Cherry MX switch by printing most of it in nylon on a Stratasys Objet 350 polyjet printer, with a tiny bit of of the housing printed with a polymer with a hardness of Shore 40. No, Shore A, Shore B, or Shore 00 was not specified, but hey, it’s just a conference paper.

The experimental test for this keyswitch was dropping a 150 gram weight from 125 mm onto the keyswitch, with a force sensitive resistor underneath the switch, connected to an Arduino. Data was logged, filtered, and fitted in Excel to create a plot of the force on dampened, rigid, and commercial switch housings. Results from ANOVA were p > 0.05 (p=0.12).

Despite the lack of significant results, there is something here. The Objet is one of the few printers that can do multimaterial printing with the resolution needed to replicate an injection molded part. There is a trend to the data, and printing squishy parts into a keyswitch should improve typing feel. There will be more work on this, but in the meantime we’re hopeful some other experimenters will pick up this train of research.

The Filament Pelletizer For Fused Granular Fabrication

December 5, 2018 by Brian Benchoff 24 Comments

The ABS and PLA that goes into your 3D printer is sold in two forms. The first, naturally, is filament. The second is plastic granules, the raw material for your filament, and costs an order of magnitude less than the filament itself. For years we’ve been seeing machines that either print directly with plastic granules or are converted into filament with fancy filament-extruding machines. Now we can do it the other way. [Aubrey Woern] and [Joshua Pearce] of Michigan Tech have been working on a polymer pelletizer chopper that takes plastic filament and turns it into pellets.

The system uses a large corded drill motor to drive a Forstner drill bit. Filament is then threaded into the top of this spinning drill bit with the help of a small DC motor and grippy wheel printed out of Ninjaflex. The system works, and the authors of the paper were able to vary the size of the chopped filament by feeding it into the Forstner bit faster or slower.

While turning an expensive product (filament) back into its raw material (pellets) may not seem like a great idea, there have been a significant number of advancements in the state of manufacturing filament on a desktop and printing directly from pellets in recent years. A machine that turns plastic back into its raw state is something that’s needed if you want to experiment with plastic recycling, and this machine is more than capable of chopping up a spool of filament in two hours or so.