An Introduction To Series Elastic Actuators For A Robot

December 3, 2015 by James Hobson 13 Comments

Perhaps one of the most interesting YouTube channels to follow right now is [James Bruton’s] channel for XRobots.co.uk — he’s a prop maker, a toy maker — and as his site implies, a robotics guru. Put them altogether and watch him make some of your childhood dream projects come true. He’s currently working on a real-life robot creation of Ultron, and he’s messing around with Series Elastic Actuators right now.

In an earlier part of the project, he built a small robotic arm to demonstrate the motion capture suit he’s going to use to control Ultron (if all goes according to plan he’ll have a walking robot following his every move!). He showed how the basic RC servo motor driven arm works, and how it probably wouldn’t be the best to scale up since it has no external feedback — if he has a full size Ultron robot swinging its arms around, someone could get hurt.

Which led him to designing his own prototype Series Elastic Actuators using an Arduino, potentiometers, some elastics, and a geared DC motor.

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OpenBionics Fabs Prosthetics As Unique As Those Who Wear Them

December 2, 2015 by Sonya Vasquez 2 Comments

Humans may all have the same overall form, but when we need to find a suitable replacement for a missing limb, it’s clear that between the variety of finger-lengths and hand-breadths, a one-size-fits-all prosthetic just wont cut it. OpenBionics puts a spin on today’s approach to prosthetics, putting forth a framework of tools that’s flexible enough to fit the spectrum of hand shapes and enables us to create our own prosthetic at home that can meet the challenge of most everyday tasks.

Minas Liarokapis of the OpenBionics team gave a talk at this year’s Hackaday SuperConference which covered the design considerations and unique features of the project. This incredible work was recognized with 2nd Prize in the 2015 Hackaday Prize. Watch Minas’ talk below, then join us after the break as we cover more details that went into developing this prosthesis.

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Upgrading A 3D Printer With A Leadscrew

November 26, 2015 by James Hobson 32 Comments

Consumer 3D printers have really opened up the floodgates to personal at home fabrication. Even the cheapest of 3D printers will yield functional parts — however the quality of the print varies quite a lot. One of the biggest downfalls to affordable 3D printers is the cost cutting of crucial parts, like the z-Axis. Almost all consumer 3D printers use standard threaded rod for the z-axis, which should really use a leadscrew instead.

Threaded rod is not designed for accurate positioning — it’s primarily designed to be a fastener. You can have issues with backlash, wobble, and they usually aren’t even perfectly straight — not to mention they gunk up easily with dirt and grime. In other words, you’ll never see a threaded rod on a commercial machine.

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A 3D Printed Car Jack? No, Seriously!

November 25, 2015 by James Hobson 48 Comments

Ah nuts, I lost my car jack again. What will I do? Well, why not 3D print a new one?

Uploaded to Thingiverse earlier this week, this design allows you to 3D print a fully functional car jack — provided your build platform is large enough. It’s actually a bit of a promo for the Cheetah 2, a massive modular 3D printer by [Hans Fouche]. Earlier this year we shared his 3D printed lawn mower; which spoiler, also works.

The neat thing about the Cheetah 2 is that it doesn’t use filament. It actually processes plastic pellets right inside the hot end, allowing for much cheaper material — typically dollars on the kilogram, as opposed to the $30+/kg we’re all used to being gouged on. Of course, you could also make your own filament. Continue reading “A 3D Printed Car Jack? No, Seriously!” →

Building A Better 3D Printed Gun

November 21, 2015 by Brian Benchoff 149 Comments

Back in 2013, [Cody Wilson] of Defense Distributed designed and built the world’s first completely 3D printed pistol. He called his gun the Liberator, after a World War II-era single-shot pistol designed to be cheap and easy to manufacture, easy to conceal, and for members of the French Resistance, ‘a great gun to obtain a better gun’.

[Cody]’s Liberator turned out to be a great gun to obtain two or three fewer fingers. Not only was this a single-shot pistol, it was a single barrel pistol; with each round fired requiring a new 3D printed barrel. Tests were carried out, explosions happened, and we couldn’t even get the thing to print. For all the media hubbub, for all the concerned legislators, the first 3D printed pistol was much ado about nothing.

3D printers are still an extremely interesting technology, and if history has proved one thing, it’s that engineers and tinkerers will keep building guns. Last week, [James Patrick] released his latest design for a working 3D printed gun. It still fires the .22lr of the Liberator, but this is a double action revolver, it won’t blow up, and if you drop it, it won’t discharge. It’s the little things that count.

[James]’ revolver is either a 6 or 8-shot revolver uses a pepper-box design, where the gun has multiple chambers and barrels in one gigantic cylinder. The double action design first rotates the cylinder to the next chamber, pulls back a striker loaded up with a firing pin nail, and (hopefully) fires a round. In the video below, [James] goes over the design of his action, and ends up showing off a few test firings of his newly designed gun.

What’s very interesting about this build is how closely the development of 3D printed firearms is following the development of historical firearms. First, we had guns that probably shouldn’t be fired, ever. Now, the technology for 3D printed guns is about up to 1830 or thereabouts. Give it a few more years and we’ll be up to 1911.

Disclaimer: if you live in the US and think this sort of thing should be illegal, contact your state representative and tell them you support a constitutional convention to remove the personal right to own and operate firearms. This right has been upheld many, many times by the judiciary, and a constitutional convention is the only way your wishes could be carried out. Your state representative probably doesn’t read Hackaday; there is no need to comment here. Let’s talk about engineering and technology instead.

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Stronger 3D Printed Parts

November 20, 2015 by Al Williams 25 Comments

When [hobbyman] wanted some 3D printed parts to attach a bag to his bike, he was worried that the parts would not be strong enough to hold when the bag was full. He decided to find a way to reinforce the part with fiberglass and epoxy. His first model had holes and grooves to be filled in with epoxy.

However, after working with the part for a bit, he decided to take a different approach. Instead of making the part nearly solid plastic with space for the epoxy, he instead created the part as a shell and then filled it with fibers and epoxy. After it all cured, a little sanding started removing some of the plastic shell and what was left was mostly a cast fiberglass part (although some of the plastic was left on).

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Diamond Hotend Opens The Color Gamut For 3D Printing

November 18, 2015 by James Hobson 53 Comments

It’s safe to say we’ve hit a bit of a plateau with hobby based 3D printers using FDM technology. Print quality is pretty high, they’re about as fast as they’re going to get, and compared to commercial machines they’re a pretty good bang for your buck. So what’s next? What about printing in color?

It is possible to print in color using a regular 3D printer and a bit of patience, but it’s really not economical or efficient. We’ve seen multiple extruder heads for 3D printing as well, but there are many problems with that due to calibration and trailing plastic from one head to another. So what if you could feed multiple color filaments into a single mixing head?

Well, it turns out you can. Earlier this year RepRap ran a Kickstarter for the development of the Diamond Hotend — a single nozzle multi-color extruder. It’s in production now and appears to work quite well. It’s also compatible with many 3D printers as long as the motherboard has triple extruder support.

However, the big question remains — how do you program a colored print? Using Repetier Host actually. You’ll need to export your 3D model in the .AMF file format, but once you do, you’ll be able to configure it for a color print job inside Repetier Host.

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