Quartet Of SMD Resistors Used To Sense Z-Axis Height

January 27, 2019 by Dan Maloney 34 Comments

Here’s a neat trick for your next 3D-printer build or retrofit: a Z-axis sensor using a DIY strain gauge made from SMD resistors. We’re betting it could have plenty of other applications, too.

Conventional load cells, at least the ones you can pick up cheaply from the usual sources or harvest from old kitchen or bathroom scales, are usually way too big to be used on the extruder of a 3D-printer. [IvDm] wanted to build a touch sensor for his Hybercube printer, so he built his own load cell to do it. It consists of four 1000 ohm SMD resistors in the big 2512 device size. He mounted them to an X-shaped PCB and wired them in the classic Wheatstone bridge configuration, with two resistors on one side of the board and two on the other.

The extruder mounts into a hole in the center of the board and floats on it. Through an HX711 load cell driver chip, the bridge senses the slight flex of the board when the extruder bottoms out on the bed, and an ATtiny85 pulls a limit switch input to ground. [IvDm] even did some repeatability testing with this sensor and it turned out to be surprisingly consistent. The first minute or so of the video below shows it in action on the Hypercube.

We found the use of SMD resistors as strain gauges pretty clever here, but there’s plenty to do with off-the-shelf load cells: measuring how much filament is left on a roll, checking the thrust of a model rocket engine, or even figuring out if you’re peeing correctly.

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Casting Concrete With 3D Printed Molds

January 27, 2019 by Al Williams 13 Comments

[Thomas Sanladerer] wanted to create some molds using 3D printing for concrete and plaster. He used a delta printer with flexible filament and documented his process in the video below.

If you’ve printed with flexible filaments before, you know you need an extruder that has a contained path. [Tom] borrowed a printer, but it didn’t have that kind of set up. The first step was to swap extruders with another printer.

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7-Segment Display Is 3D Printed And Hand Cranked

January 26, 2019 by Mike Szczys 17 Comments

[Peter Lehnér] has designed a brilliant 7-segment flip-segment display that doesn’t really flip. In fact, it doesn’t use electromagnets at all. This one is 3D printed and hand cranked. It’s a clever use of a cam system to set the segments for each digit (0-9) makes it a perfect entry in the Hackaday 3D Printed Gears, Pulleys, and Cams contest.

We find the nomenclature of these displays to be a bit confusing so let’s do a quick rundown. You may be most familiar with flip-dot displays, basically a dot-matrix grid of physical pixels that are black on one side and brightly colored (usually chartreuse) on the other. We saw a giant flip-dot display at CES four years ago. Akin to flip-dots are flip-segment displays which do the same thing but with segments of a digit rather than dots. We featured a 3D printed version of these last week. The common aspect of most flip displays is an electromagnet used to change the state of the dot or segment.

The version [Peter] designed gets rid of the magnets and coils, replacing them with mechanical logic instead. Each segment sits in a track on the frame of the digit. When slid to one position it is hidden by the bezel, in the other position it slides into view. A cleverly designed set of cams move the segments at each of 10 positions. The animated graphic here shows three cams which are responsible for moving just two of the segments. More cams are added to complete assembly, a process shown in the second half of the demo video found below.

We’re delighted to see this as an entry in the contest and can’t wait to see what kind of gear, cam, or pully scheme is built into your projects!

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Building A 3D Printer That Goes Where You Do

January 21, 2019 by Tom Nardi 13 Comments

Back when one of the best paths to desktop 3D printer ownership was building the thing yourself from laser cut wood with some string thrown in for good measure, just saying you had one at home would instantly boost your hacker street cred. It didn’t even need to work particularly well (which is good, since it probably didn’t), you just had to have one. But now that 3D printers have become so common, the game has changed. If you want to keep on the cutting edge, you’ve got to come up with a unique hook.

Luckily for us, [Thomas Sanladerer] is here to advance the status quo of desktop 3D printing. Not content with a 3D printer that spends its time loafing around the workshop, he decided to build a completely mobile 3D printer. For a guy who spends a lot of time traveling to different 3D printing conferences and shows, this is actually a pretty handy thing to have around, but there are probably some lessons to be learned here even if you aren’t a 3D printing YouTube celebrity.

Given the wide array of very popular low cost 3D printers out there, some will likely be surprised that [Thomas] decided to mobilize a printer which is nearly an antique at this point: the PrinterBot Play. But as he explains in the video after the break, the design of the Play really lends itself perfectly to life on the road. For one, it’s an extremely rigid printer thanks to its (arguably overkill) steel construction. Compared to most contemporary 3D printers which are often little more than a wispy collection of aluminium extrusion and zip ties, the boxy design of the Play also offers ample room inside for additional electronics and wiring

The most obvious addition to the PrintrBot is the six Sony NP-F camera batteries that [Thomas] attaches to the back of the printer by way of 3D printed mounts, but there’s also quite a bit of hardware hidden inside to break the machine free from its alternating current shackles. The bank of batteries feed simultaneously into a DC boost converter which brings the battery voltage up to the 12 V required for the printer’s electronics and motors, and a DC regulator which brings the voltage down to the 5 V required by the Raspberry Pi running OctoPrint. There’s even a charge controller hiding in there which not only frees him from carrying around a separate charger, but lets him top up the cells while the printer is up and running.

On the software side of things, the Raspberry Pi is configured to work as a WiFi access point so that OctoPrint can be controlled with a smartphone even if there’s no existing network in place. A fact demonstrated when he takes the printer outside for a walk while it’s in the middle of a job. The ability to control the printer without any existing infrastructure combined with the estimated six hour runtime on a charge means this modified PrinterBot can get the job done no matter where [Thomas] finds himself.

The hacker community was saddened by the news that PrintrBot was closing its doors last year, an unfortunate casualty of an increasingly competitive desktop 3D printing market. But perhaps we can take some comfort from the fact that their eminently hackable open source printers still live on in projects such as this.

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Hackaday Superconference: 3D Printing For Electronics

January 21, 2019 by Brian Benchoff 12 Comments

For her day job, Amie D Dansby works as a software simulation developer, creating simulations for video games. In her free time, she’s implanting the key to her Tesla in her arm, building cordwood jewelry and cosplay swords, and seeking out other adventures in electronics and 3D printing. Amie has made a name for herself in the 3D printing community, and she is surrounded by fans when she attends the RepRap meetups and Maker Faires.

She was also popular at this year’s Hackaday Superconference, where she gave a talk on the integration of 3D printing and electronics. Amie’s work concentrates on props and cosplay, which is a skill unto itself, and you only need to look at some of the old Mythbusters, the documentary footage from ILM, or even model makers to realize this is an arcane art that takes a lot of skill. Lucky for us, Amie was there to show us the tricks she’s picked up over the years to make building a one-off piece easier than you could imagine.

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Unobtanium Bezels Finally Modeled For 3D Printing

January 19, 2019 by Brian Benchoff 26 Comments

In 1991, Apple released the Quadra line of computers, named after their utilization of the new Motorola 68040 CPU. The Quadra line initially consisted of two models, the Quadra 700 and the Quadra 900. These two models, and the Quadra 950, released as a slight upgrade to the 900, were the peak of performance. You could conceivably load these machines up with 256 Megabytes of RAM, in an era where hard drives hovered around 80 Megabytes. This much RAM would cost as much as a house. These were powerhouses, the first ProTools workstations, and they ran Jurassic Park. If you wanted peak performance in the early 90s, you got a Quadra.

The Quadra 900 and 950 were tower computers, and there were options for floppy, Zip drives, Bernoulli drives, and a CD-ROM drive. They were introduced a little before the ‘multimedia’ hubub, and right now, the plastic bezel for the CD-ROM option is an absurdly expensive piece of plastic. People have paid $150 for an original CD-ROM bezel. Seems like the perfect application of 3D printing, doesn’t it? That’s exactly what [360alaska] over on the 68k Macintosh Liberation Army forms did. The unobtanium bezel can now be sent off to Shapeways.

This project is a continuation of a thread where various forum members shared their .STLs for random bits of Apple plastic, ranging from rubber feet for PowerBooks to the clip-on ‘programmer’s switch’ for the Macintosh SE. The crowning achievement of this community endeavour is the Quadra 950 CD-ROM bezel. There are a few varieties, ranging from one that fits a standard 5 1/4″ drive, to a nearly exact replica of the official Apple offering for their official drive. All the files are there for the downloadin’.

Printing these bezels will be a bit of a challenge for a filament-based printer, but resin printers are getting cheap and Shapeways is always there for you. Painting to match the brominated patina of old plastic is also a challenge, but the forum members have had some success with off-the-shelf spray paints.

Talking With Bubbles

January 18, 2019 by Al Williams 3 Comments

Despite the title, this isn’t a tale of conversing with Michael Jackson’s chimp. Rather, it is about [KyungYun]’s machine that transforms speech into whimsical bubbles. While the speech control is novel, we were more fascinated with how the mechanism uses a system of strings to blow bubbles, along with the workmanship to make the device portable.

The rate of fire isn’t that great, so the bubbles appear to simply get larger the longer you talk. Essentially, the device increases the size of the iris — the part that blows the bubble — until you pause speaking. Then it burps out a bubble.

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