Bolt-On Stepper Motor Driver For The Raspberry Pi

August 13, 2019 by Tom Nardi 9 Comments

For his entry into the 2019 Hackaday Prize, [Tobius Daichi] is working on adding some motion control capabilities to everyone’s favorite Linux SBC. His 3+Pi board attaches to the Raspberry Pi’s GPIO header and gives you a convenient way to control four individual stepper motors. Perfect for a 3D printer, laser cutter, CNC, or anything else you can think of that needs to move in a few dimensions.

But such a simplistic description of the 3+Pi might be underselling it a bit. While [Tobius] says he was inspired by the classic Arduino CNC Shield that powers countless DIY 3D printers, he’s managed to improve on the concept. Rather than having the host Pi communicate directly with the stepper drivers, the 3+Pi features an onboard STM32F302CBT6 that handles the actual motor control. The Pi just needs to tell it what to do over UART.

If you’re looking to do things in real-time, having an onboard microcontroller handle the low-level aspects of talking to the stepper drivers can be a big help. A natural extension for this board could be support for the Klipper firmware, which leverages the fact that the Raspberry Pi is many times more powerful than your average 3D printer control board. With the Pi handling the math and providing the microcontroller instructions, Klipper allows for faster and more accurate printing than the microcontroller alone could accomplish.

As for the stepper drivers themselves, [Tobius] has decided to go with the Trinamic TMC2041-LA-T. This chip is notable as it puts dual drivers in one 48-QFN package, which is great if you’re looking to save space on your board. Some might complain that the 3+Pi doesn’t allow for easily swapping out the stepper drivers if you manage to cook one like on the Arduino CNC shield, but realistically you could say the same about many purpose-built stepper control boards.

[Tobius] is tackling this project by himself currently, but does mention that he’s open to teaming up with anyone who’s got an interest in this sort of thing. There have been previous attempts at creating Linux-powered 3D printer controllers in the past, but we think this approach holds particular promise if for no other reason than the Raspberry Pi’s popularity.

EL Wire Makes For A Great Faux-Neon Sign

August 12, 2019 by Lewin Day 11 Comments

Neon signs are attractive, but require specialised tools and skills for their manufacture. If you don’t have time to learn glass blowing and source the right gasses, you’re pretty much out of luck. However, EL wire can give a similar aesthetic, and with an off-the-shelf power supply it is easy to hook up and get working. [sjm4306] combined this with 3D printing for a quick and easy build.

The project starts by selecting a Nintendo 64 neon sign as a basis for the design. An image of the sign was traced in Inkscape, and an outline imported into CAD software. From there, a frame was designed with posts for the EL wire to wrap around, and holes for it to pass through to the back of the sign. The frame was then 3D printed, and laced with EL wires in the requisite colors.

The final result is impressive, with the EL wire serving as a great small-scale simulacrum of neon tubes. It’s a construction method that should scale as large as your 3D printed assemblies can go, too. If you need to get to grips with how it works, there’s a tutorial available for working with EL wire. Video after the break.

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Bearing-reinforced Stepper Tackles Hefty Axial Loads

August 11, 2019 by Sonya Vasquez 32 Comments

These days, it’s common among us hackers to load a stepper motor with forces in-line with their shaft–especially when we couple them to leadscrews or worm gears. Unfortunately, steppers aren’t really intended for this sort of loading, and doing so with high forces can destroy the motor. Fear not, though. If you find yourself in this situation, [Voind Robot] has the solution for you with a dead-simple-yet-dead-effective upgrade to get your steppers tackling axial loads without issue.

In [Voind Robot’s] case, they started with a worm-gear-drive on a robot arm. In their circumstances, moving the arm could put tremendous axial loads onto the stepper shaft through the worm–as much as 30 Newtons. Such loads could easily destroy the internal stepper motor bearings in a short time, so they opted for some double-sided reinforcement. To alleviate the problem, the introduced two thrust bearings, one on either side of the shaft. These thrust bearings do the work of redirecting the force off the shaft and directly onto the motor casing, a much more rigid place to apply such loads.

This trick is dead simple, and it’s actually over five years old. Nevertheless, it’s still incredibly relevant today for any 3D printer builder who’s considering coupling a leadscrew to a stepper motor for their Z-axis. There, a single thrust bearing could take out any axial play and lead to an overall rigid build. We love simple machine-design nuggets of wisdom like these. If you’re looking for more printer-design tricks, look no further than [Moritz’s] Workhorse Printer article.

Acoustic Lenses Show Sound Can Be Focused Like Light

August 10, 2019 by Donald Papp 30 Comments

Acoustic lenses are remarkable devices that just got cooler. A recent presentation at SIGGRAPH 2019 showed that with the help of 3D printing, it is possible to build the acoustic equivalent of optical devices. That is to say, configurations that redirect or focus sound waves. One fascinating demonstration worked like an acoustic prism, able to send different notes from a simple melody in different directions. Another was a device that dynamically varied the distance between two lenses in order to focus sound onto a moving target. In both cases, the sounds originate from an ordinary speaker and are shaped by passing through the acoustic lens or lenses, which are entirely passive devices.

Researchers from the University of Sussex used 3D printing for a modular approach to acoustic lens design. 16 different pre-printed “bricks” (shown here) can be assembled in various combinations to get different results. There are limitations, however. The demonstration lenses only work in a narrow bandwidth, meaning that the sound they work with is limited to about an octave at best. That’s enough for a simple melody, but not nearly enough to cover a human’s full audible range. Download the PDF for a quick read about the details, it’s only two pages but loaded with enough to whet your appetite to know more.

Directional sound can be done in other ways as well, such as using an array of ultrasonic emitters to create a coherent beam of sound. Ultrasonic emitters can even levitate lightweight objects. Ain’t sound neat?

3D Printing Makes Modular Payload For Model Rocket

August 9, 2019 by Donald Papp 2 Comments

Putting payloads into model rockets can be more complex than simply shoving stuff into an open spot, so [concretedog] put some work into making a modular payload tube for his current rocket. The nose cone for his rocket is quite large, so he opted to give it a secure payload area that doesn’t compromise or interfere with any of the structural or operational bits such as the parachute.

The payload container is a hollow tube with a 3D printed threaded adaptor attached to one end. Payload goes into the tube, and the tube inserts into a hole in the bulkhead, screwing down securely. The result is an easy way to send up something like a GPS tracker, possibly with a LoRa module attached to it. That combination is a popular one with high-altitude balloons, which, like rockets, also require people to retrieve them after not-entirely-predictable landings. LoRa wireless communications have very long range, but that doesn’t help if there’s an obstruction like a hill between you and the transmitter. In those cases, a simple LoRa repeater attached to a kite, long pole, or drone can save the day.

We’ve seen [concretedog]’s work before, when he designed stackable PCBs intended to easily fit inside model rocket bodies, allowing for easy integration of microcontroller-driven functions like delayed ignitions or altimeter triggers. Better development tools, hardware, and 3D printing has really helped make smarter rocketry more accessible to hobbyists.

3D-Printed Extension For Extreme Macro Photography Includes Lens Electronic Control

August 9, 2019 by Jenny List 24 Comments

Macro photography — the art of taking pictures of tiny things — can be an expensive pastime. Good lenses aren’t cheap, and greater magnification inflates the price even further. One way to release a bit more performance from your optics comes in the form of an extension tube, which mounts your lens further from the camera to zoom in a little on the image. Back in the day with a film SLR you could make a rough and ready tube with cardboard and tape, but in the age of the digital camera the lens has become as much a computer peripheral as an optical device. [Nicholas Sherlock] has solved this problem by creating a 3D-printed extension tube for his Canon that preserves connections between camera and lens.

More details of this 300mm monster’s construction go so far beyond a plastic tub formed of two threaded sections with adapter plates at the ends. He’s using off-the-shelf metal rings to fit camera and lens just right, but making the electronic contacts is where it gets interesting. On end uses pogo pins, the other provides a contact block made of nail heads. In both cases the 3D-printed parts are designed to provide mounting points for the pins and nails. The assembly technique is worth a look both because of the design and as an example of how to document all the juicy details we’re constantly looking for in a great hack.

The results speak for themselves, in that the photography provides an impressive level of close-up detail. If you would like to build your own tube, it is available on Thingiverse.

Macro extensions seem far between here, but we’ve brought you a few lens repairs in our time.

[via /r/photography]

3D Printing Glass

August 8, 2019 by Al Williams 26 Comments

For most of us, 3D printing means printing in plastic of some sort — either filament or photo resin. However, we have all wanted to print in other materials — especially more substantial materials. Metal printers exist but they aren’t cheap. However, it is possible to print molds and cast metal parts using them. [Amos Dudley] prints molds. But instead of metal, he casts parts out of glass.

[Amos] covers several techniques. The first is creating a relief (that is a 3D shape that grows out of a base). According to the post, this prevents difficult undercuts. He then casts a mold from silica and uses a kiln to melt glass into the mold. You might expect to do that with a full-size kiln, but you can actually get an inexpensive small kiln that fits in your microwave oven.

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