3D Printed Radius Gauge, Just Add Calipers (And A Wee Bit Of Math)

September 9, 2018 by Donald Papp 16 Comments

With 3D printed arms of fixed measurements, the depth reading from a set of digital calipers can be used to calculate the radius of a curve.

Specialized tools that focus on one particular job tend to get distilled right down to their essentials and turned in an economical consumer product. One example of this is radius (or fillet) gauges: a set of curves in different sizes that one uses to measure the radius of a curved surface by trial and error. To some, such products represent solved problems. Others see opportunities for a fresh perspective, like this caliper-enabled 3D printed radius gauge by [Arne Bergkvist].

[Arne]’s 3D printed radius gauge is a simple object; a rigid attachment for a nearly ubiquitous model of digital caliper. By placing the curve to be measured between the two arms of the device and using the depth measurement of the caliper to measure distance to the curve’s surface, a simple calculation (helpfully printed on the unit itself) of radius = distance * 2.414 reveals the radius of the curve. However, this shortened calculation makes a number of assumptions and only works for [Arne]’s specific design.

Another version by [Fredrik Welander] represents a more flexible take on the same concept. His RadGauge design (pictured up top) has a few different sizes to accommodate a variety of objects, and his Git repository provides a calculator tool as well as some tips on fine tuning to allow for variations in the dimensions of the printed attachment.

3D printing has opened a lot of doors, and items like this show that the plastic doodads created aren’t always the end result in and of themselves; sometimes they are the glue that enables a tool or part to work in a different way. To help get the most out of 3D printing, check out the in-depth coverage of how to best tap 3D printed parts for fasteners, and [Roger Cheng]’s guide to using 3D printed brackets and aluminum extrusion to make just about anything.

Cheap FPV Goggles Turned Pocket Sized Display

September 8, 2018 by Tom Nardi 10 Comments

Thanks to the exploding popularity of First Person View (FPV) RC flying over the last couple of years, the cost of the associated hardware has dropped rapidly. Today you can get entry-level FPV goggles for under $40 USD on various import sites. For the money you’re getting a 5.8 GHz receiver, battery, and an LCD display; even if the components themselves aren’t exactly high end, at that price it’s essentially an impulse buy.

[nomand] didn’t necessarily have a use for a cheap FPV headset, but he did like the idea of having a pocket sized display that he could pass off to others so they could see what he’s seeing during flights. So he harvested the principle components from a Eachine VR006 headset and designed a new 3D printed enclosure for them. The final result looks fantastic, and is much cheaper than commercial alternatives on the market.

He’s created an exceptionally detailed step-by-step guide on how you can perform the conversion yourself in the project’s GitHub repository, and has also put together a video where he goes over the modification and discusses the end result. [nomand] clearly intends for this to be a project for others to duplicate instead of a one-off build, and given the price and final results, we wouldn’t be surprised if this conversion becomes popular in FPV circles.

Perhaps the best part of this project is that it requires almost no modification of the original hardware; just soldering two wires because the original connector is too large. Otherwise just need to take the headset apart carefully, and transplant the components into the 3D-printed case [nomand] has meticulously designed. The case is so well designed it doesn’t even need any fasteners, it slides together and everything is held in with some strategically placed pieces of foam.

Between this modification and the custom built spectator display we covered recently, it looks like there’s a clear demand for sub-$50 portable FPV monitors. Seems odd that no manufacture is trying to fill this niche so far.

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Moving 3D Printed Prosthetic Arms With A Pulse

September 7, 2018 by Brian Benchoff 4 Comments

One of the best uses of 3D printers we’ve seen are custom prosthetics. Even today, custom-built prosthetics cost an arm and a leg, but there’s no reason why they should. Right now, we can scan someone’s arm or leg, import that scan into a 3D-modeling program, and design a custom-fit orthotic that can be spit out on a 3D printer. Now, we’re seeing some interesting methods of turning those 3D-printed parts into the beginnings of a cybernetic design. This is a custom printed robotic hand controlled by a pulse sensor. It’s in its early stages right now, but so far the results are promising and this is a great entry to The Hackaday Prize

This project draws upon a few of the team’s other endeavours. The first is a 3D-printed mini linear actuator, a project that made it into the finals of the Hackaday Prize in the Robotics Module challenge. This tiny linear actuator is actually powered by a tiny hobby servo rigged up for continuous rotation. Add in some 3D printed gears and a well-designed frame, and you have something that’s just as good as fantastically expensive linear actuators as a bargain basement price. This pulse sensor arm also makes use of the team’s TNS 1i, a 3D printed robotic hand that makes use of those tiny little linear actuators.

Of course, if you’re going to build a prosthetic robotic arm, you have to have some sort of brain-machine interface. Previously, the team was using Myoware muscle sensors to control the opening and closing of the fingers. This changed, however, when [Giovanni] was trying to get his Samsung gear S3 to detect his pulse. Apparently, moving your wrist when trying to get a smartwatch to listen in on your heartbeat is an acceptable substitute for a muscle sensor.

3D Printed RC Jet Boat Gets Up To Speed

September 5, 2018 by Tom Nardi 9 Comments

In one of those weird twists of fate, there’s currently a very high chance that anyone who owns a 3D printer has made a boat with it. In fact, they’ve probably printed several of them, so many that they might even have a shelf filled with little boats in different colors and sizes. That’s because it’s a popular benchmark to make sure the printer is well calibrated. But if you’re going to spend hours printing out a boat, why not print one that’s got some punch?

This 3D printable jet boat designed by [Jotham B] probably isn’t a great print to check your desktop machine’s calibration on, in fact you’re going to want to make sure you’ve got everything dialed in before taking on this challenge. If the classic “Benchy” is the beginners boat, then this is certainly for the 3D printing veterans. But if you’ve got the skills to pull it off, and some RC gear laying around to outfit it with, this could be a great project to end your summer on.

Unless you’ve got an exceptionally tall printer, the 460mm long hull will need to be printed in several pieces and then grafted back together. You could potentially use glue, but something a bit more robust like welding the parts together with a soldering iron is a better bet to make sure your printed boat doesn’t do its best Titanic reenactment out on the lake.

[Jotham] recommends printing the impeller at 0.15mm layer height, as you’ll want all the detail you can muster to provide a smooth surface. You’ll also need to use supports, so expect to spend a fair bit of time cleaning it up post-print. The rest of the model can be printed at 0.3mm, which is going to save a lot of time on the hull. All told, it will take about half a roll of filament to print all the parts for the boat (assuming no mistakes), which puts the pre-electronics cost at around $10 USD.

Speaking of electronics, you’ll need a RC receiver, a servo for steering, an electronic speed controller (ESC), and a suitable motor. [Jotham] used a 3674 brushless motor with a 120A water-cooled ESC, but notes that the setup is way overpowered. In the video after the break you can see the boat spends as much time airborne as it does in the water, which might look cool, but isn’t exactly efficient.

If you want to round out your 3D PLA fleet, we’ve also seen a printed FPV lifeboat as well as a hydrofoil that “flies” through the water.

[Thanks to Aidan for the tip.]

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A Servo Powered Robotic Arm, But Like You’ve Never Seen Before

September 4, 2018 by Ben James 26 Comments

We’ve written about a lot of DIY robotic arms. Some of them are high-performance, some are inexpensive, and some are just uniquely fun. This one certainly falls into the last category; whilst watching an episode of Black Mirror, [Gear Down For What] was struck by inspiration for a thin robotic limb. After some iterations he has a final prototype, and it’s quite something to see in action.

To make a robotic arm as slender as possible, the actuators can’t be mounted on the arm itself but must instead drive the arm remotely. There are a number of ways of doing this, and though [Gear Down For What] considered using pneumatics or hydraulics, he opted to keep it simple with RC servos which produced a nifty solution that we really like.

The arm is made out of a series of 3D printed ball joints, allowing rotation in any direction. The tricky bit is transferring the force from the servos to each joint. Initially bare fishing line was considered, but this made the remote joints difficult to control when lower joints were moving. The solution was to use the fishing line inside of tubing, similar to the way that bike brakes operate. This allows the force to be carried to the appropriate joint regardless of lower movement. Each joint needs an x and y tension to allow it to rotate in any direction, which means an army of sixteen servos is needed to operate the eight segment arm.

Robotic arms are always fun to build and we’ve seen some pretty neat uses for them, such as mapping magnetic fields in 3D, or teaching sign language.

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Chemistry And Lasers Turn Any Plastic Surface Into A PCB

September 4, 2018 by Dan Maloney 30 Comments

On the face of it, PCB production seems to pretty much have been reduced to practice. Hobbyists have been etching their own boards forever, and the custom PCB fabrication market is rich with vendors whose capabilities span the gamut from dead simple one-side through-hole boards to the finest pitch multilayer SMD boards imaginable.

So why on Earth would we need yet another way to make PCBs? Because as [Ben Krasnow] points out, the ability to turn almost any plastic surface into a PCB can be really handy, and is not necessarily something the fab houses handle right now. The video below shows how [Ben] came up with his method, which went down a non-obvious path that was part chemistry experiment, part materials science. The basic idea is to use electroless copper plating, a method of depositing copper onto a substrate without using electrolysis.

This allows non-conductive substrates — [Ben] used small parts printed with a Formlabs SLA printer — to be plated with enough copper to form solderable traces. The chemistry involved in this is not trivial; there are catalysts and surfactants and saturated solutions of copper sulfate to manage. And even once he dialed that in, he had to figure out how to make traces and vias with a laser cutter. It was eventually successful, but it took a lot of work. Check out the video below to see how he got there, and where he plans to go next.

You’ve got to hand it to [Ben]; when he decides to explore something, he goes all in. We appreciate his dedication, whether he’s using candles to explore magnetohydrodynamics or making plasma with a high-speed jet of water.

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Printed It: Logitech C270 Conversion

September 4, 2018 by Tom Nardi 14 Comments

One of the most practical applications for a home 3D printer is the ability to produce replacement parts; why wait a week for somebody to ship you a little plastic widget when you’ve got a machine that can manufacture a facsimile of it in a couple of hours? But what if your skills and passion for the smell of melting PLA push you even farther? You might move on from printing replacement parts to designing and building whole new devices and assemblies. Arguably this could be considered “peak” 3D printing: using a printer to create new devices which would otherwise be difficult or impractical for an individual to manufacture by more traditional means.

A perfect example is this fantastic total conversion for the Logitech C270 webcam designed by [Luc Eeckelaert]. Officially he calls it a “tripod”, and perhaps that’s how the design started, but the final product is clearly much more than that. It puts the normally monitor-mounted Logitech camera onto an articulated arm, greatly improving the device’s usability. The conversion even includes the ability to manually adjust the focus, a feature the original hardware doesn’t have. It turns the affordable and widely available Logitech C270 into an excellent camera to have on the workbench for documenting projects, or pointing at the bed of your 3D printer.