A Better Bowden Drive For Floppy Filaments

May 16, 2019 by Dan Maloney 7 Comments

You might not think to use the word “rigid” to describe most 3D-printer filaments, but most plastic filaments are actually pretty stiff over a short length, stiff enough to be pushed into an extruder. Try the same thing with a softer plastic like TPE, though, and you might find yourself looking at this modified Bowden drive for elastomeric filaments.

The idea behind the Bowden drive favored by some 3D-printer designers is simple: clamp the filament between a motor-driven wheel and an idler to push it up a pipe into the hot end of the extruder. But with TPE and similar elastomeric filaments, [Tech2C] found that the Bowden drive on his Hypercube printer was causing jams and under-extrusion artifacts in finished prints. A careful analysis of the stock drive showed a few weaknesses, such as how much of the filament is not supported on the output side of the wheel. [Tech2C] reworked the drive to close that gap and also to move the output tube opening closer to the drive. The stock drive wheel was also replaced with a smaller diameter wheel with more aggressive knurling. Bolted to the stepper, the new drive gave remarkably improved results – a TPE vase was almost flawless with the new drive, while the old drive had blobs and artifacts galore. And a retraction test print showed no stringing at all with PLA, meaning the new drive isn’t just good for the soft stuff.

All in all, a great upgrade for this versatile and hackable little printer. We’ve seen the Hypercube before, of course – this bed height probe using SMD resistors as strain gauges connects to the other end of the Bowden drive.

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Microscope-Inspired Toolchanger Spins Multicolor 3D Prints

May 15, 2019 by Sonya Vasquez 15 Comments

The 3D printing community is simply stirring with excitement over toolchanging printers, but these machines are still the exception rather than the norm. Here’s an exceptional exception: [Paul Paukstelis] built a five-color printer with a novel head-changing solution.

[Paul’s] 3D printer is a hat-tip to anyone who’s spent time in the wetlab. For starters, the printer is born from the remains of a former liquid handling system, a mighty surplus score. When it comes to headchanging, [Paul] combined some honest inspiration from E3D’s toolchanging videos with some design features borrowed from the microscope in his lab. The result is that the printer’s five-tool head-changer mechanically behaves very similarly to the nose piece in a compound light microscope.

Because the printer evolved from old lab equipment, [Paul] dubs his printer into a lineage that he calls the “Reclaimed Rapid-Prototyper,” or the RecRap. Best of all, he’s kindly posted up the CAD files on the Thingiverse such that you too can take a deep look into this head-changing solution.

We love seeing these tools get a second life, and we think there’s plenty of potential for new offspring in this lineage of discarded lab equipment.

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For Better Photogrammetry, Just Add A Donut

May 14, 2019 by Kristina Panos 19 Comments

If you don’t have access to a 3D scanner, you can get a lot done with photogrammetry. Basically, you take a bunch of pictures of an object from different angles, and then stitch them together with software to create a 3D model. For best results, you need consistent, diffuse lighting, an unchanging background, and a steady camera.

Industrial designer [Eric Strebel] recently made an Intro to Photogrammetry video wherein he circled an object taking photos with his bare hands. One commenter suggested a different method: build a donut-shaped turntable that circles the object, which sits on a stationary platform. Attach the camera to the donut, counterbalance the weight, and Bob’s your proverbial uncle. [Eric] thought it was a brilliant idea (because it is), and he built a proof of concept. This is that video.

[Eric] can move the camera up and down the arc of the boom to get all the Z-positions he wants. The platform has a mark every 10° and there’s a pointer in the platform to line them up against for consistent camera positioning. He was pleasantly surprised by the results, which we agree are outstanding.

We always learn a lot from [Eric]’s videos, and this one’s no exception. Case in point: he makes a cardboard mock-up by laying out the pieces, and uses that to make a pattern for the recycled plywood and melamine version. In the photogrammetry video, he covers spray paint techniques to make objects reflect as little light as possible so the details don’t get lost.

If you prefer to rotate your objects, get an Arduino out and automate the spin.

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Custom Storage Boxes, From Cardboard And 3D Printed Bits

May 13, 2019 by Donald Papp 14 Comments

It’s not that storage boxes and organizers are hard to find. No, the problem this project set out to solve was more nuanced than that. The real trouble [theguymasamato] had was that his storage options — wide shelves and deep drawers — weren’t well suited to storing a lot of small and light objects. The result was a lot of wasted space and poor organization. To make matters worse, his big drawers had oddball dimensions, meaning that store bought organizers weren’t a good fit either.

To solve these problems, [theguymasamato] decided to design his own stackable boxes to store small and light objects far more efficiently than before. The design also allows the boxes to be made in a variety of sizes without changing any of the 3D printed parts. Carefully measured and cut cardboard is critical, but that’s nothing a utility knife and ruler can’t solve. The only other requirements are a few simple plastic parts, and some glue. He can fit six of these inside a single one of his drawers with enough room to access and handle them, but without wasting space.

Cardboard is really versatile stuff. Not only has it been behind some amazingly complex devices such as this tiny working plotter, but we’ve seen it form major components in the remarkably ambitious cardboard CNC.

3D-Printed Mobius Strip Of Gears

May 11, 2019 by Lewin Day 12 Comments

Exploring the mathematics behind everyone’s favourite unorientable single-sided surface can be quite the mind-bending exercise, so it’s nice that it’s so easy to make a Mobius strip out of paper and a single piece of tape. That demonstration was far from enough for [elmins]. who printed this Mobius strip of gears. The teeth fit together, and all the gears move, but there is still only one side and one edge (we think).

This animation helped spawn the project.

The idea to tackle the project came from seeing an animation of Mobius gears. Wondering if it would be possible to actually create such a thing, [elmins] got to work. The design is printed in 60 pieces, 30 each for the inner and outer parts. The entire assembly is printed in PETG, an unconventional choice but by no means unsuitable. 285 ball bearings help the rings rotate.

The gears use a standard involute bevel profile, though [elmins] suspects this could be an area of further optimisation. The parts were printed in an orientation to ensure the print lines run around the races, allowing for minimal finishing and smooth rolling of the bearings. This is a good study of just what can be achieved with some smart modelling and perseverance.

If you’re thirsty for more madcap machining, consider exploring the concept of the Reuleaux triangle bearing.

Improving A Conference Badge With 3D Printing

May 10, 2019 by Tom Nardi 2 Comments

The obsession with over-the-top-hardware conference badges means that we as attendees get to enjoy a stream of weird and wonderful electronic gadgets. But for the folks putting these conferences on, getting a badge designed and manufactured in time for the event can be a stressful and expensive undertaking. To keep things on track, the designs will often cut corners and take liberties that you’d never see in commercial products. But of course, that’s part of their charm.

As a case in point, the OLED display on the 2019 KiCon badge is held on with just four soldered header pins, and can easily be bent or even snapped off. So [Jose Ignacio Romero] took it upon himself to develop a 3D printable mount which integrates with the PCB and gives the display some mechanical support. Any KiCon attendees who are looking to keep their badge in peak fighting condition for the long haul might want to start warming their extruders.

The design of this upgrade was made all the easier thanks to the fact that the KiCon badge is (naturally) open hardware. That meant [Jose] could import the PCB files directly into FreeCAD and have a virtual model of the badge to work with. This let him check the clearances and position of components without having to break out the calipers and measure the real thing.

Playing around with the virtual assembly, [Jose] quickly realized that the mounting holes in the OLED display don’t actually line up with the holes in the PCB; potentially why the screen didn’t get mounted on the final hardware. Once this misalignment was characterized, he was able to factor it into his design: the PCB side gets screwed down, and the screen snaps into printed “nubs” on the top of the mount.

Hackaday Editor-in-Chief [Mike Szczys] was on hand for KiCon 2019, and was kind enough to share the experience with those of us who couldn’t make it in person, including his own bout of hacking this very same badge.

A 32-bit Boost For Your 3D Printer

May 10, 2019 by Tom Nardi 52 Comments

It might not be the kind of thing you’ve given much thought to, but if you’ve ever used a desktop 3D printer, it was almost certainly being controlled by an 8-bit CPU. In fact, the common RAMPS controller is essentially just a motor driver shield for the Arduino Mega. Surely we can do a bit better than that in 2019?

For his entry into this year’s Hackaday Prize, [Robert] is working on a 32-bit drop-in replacement board which would allow 3D printer owners to easily upgrade the “brain” of their machines. Of course, there are already a few 32-bit control boards available on the market, but these are almost exclusively high-end boards which can be tricky to retrofit into an older machine. It should also go without saying that they aren’t cheap.

With this board, [Robert] is hoping to create a simpler upgrade path for 8-bit printer owners. Being small and cheap is already a pretty big deal, but perhaps equally importantly, his board is running the open source Marlin firmware. Marlin powers the majority of 8-bit desktop 3D printers (even if their owners don’t necessarily realize it) so sticking with it means that users shouldn’t have to change their software configuration or workflow just because they’ve upgraded their controller.

The board is powered by a 72 MHz STM32F103 chip, and uses state-of-the-art Trinamic TMC2208 stepper drivers to achieve near silent operation. The board has an automatic cooling fan to help keep itself cool, and with an XT60 connector for power, it should even be relatively easy to take your printer on the go with suitably beefy RC batteries.