Hackaday Links: July 29, 2018

July 29, 2018 by Brian Benchoff 17 Comments

Another holy scroll for the Church of Robotron. PoC || GTFO is a semi-annual journal of hardware exploitation, and something you must read. About a year ago, No Starch Press released the first Bible of PoC || GTFO, and now it’s time for a new testament. PoC || GTFO Volume 2 is out now, covering Elegies of the Second Crypt War to Stones from the Ivory Tower, Only as Ballast. It’s still Bible-shaped, with a leatherette cover and gilt edges.

KiCad version 5 is out, and you know what that means: It’s time to start on version 6. To that end, CERN has opened up the floodgates where you, yes, you can donate to KiCad development. The team is looking for 600 hours of development and 30,000 Swiss Francs or about that many US Dollars. As of this writing (last Wednesday), more than 200 people have donated, at an average donation per person of about 80 CHF.

Oh good, this is finally over. Qualcomm will not be buying NXP. Previously, Reuters reported Qualcomm would purchase the other semiconductor manufacturer for $38 Billion, the largest semiconductor deal ever. There were earlier rumors of an acquisition. The deal was struck down by Chinese regulators, and speculation rages that this is a reaction to the US/China trade war. Qualcomm now has to pay NXP $2 Billion in fees, which they could use to dig out some of the unobtanium Motorola datasheets locked away in a file cabinet.

The uStepper (or μStepper, whatever) is a neat little add-on to standard NEMA stepper motors. It bolts to the back and gives you the ability to control a stepper over a standard serial bus, with a built-in encoder. Now there’s a new Kickstarter for an improved version that uses the Trinamic TMC2208 ‘silent’ motor driver. That Kickstarter is just a draft now, but if you’re planning a 3D printer build, this could be what you’re waiting for.

An MRI-Safe 3D Printed Pneumatic Stepper Motor

July 26, 2018 by Tom Nardi 33 Comments

You will no doubt have seen those videos where MRI machines suck up all sorts of metallic objects with hilariously disastrous results. The magnetic field in one of these machines can easily pull in metal objects from across the room, exerting a force of several hundred pounds on any ferrous object unlucky enough to wander too close. As you can probably imagine, designing mechanical devices that can operate in such an intense magnetic field is exceptionally difficult.

But this fully 3D printed pneumatic stepper motor designed by [Foad Sojoodi Farimani] might one day change that. The PneuAct, which he presented at the recent International Conference on Robotics and Automation (ICRA) in Brisbane, Australia, manages to run at up to 850 RPM with full position control using bursts of air rather than electronic pulses. Made entirely of plastic and without any electronic components, the PneuAct can not only operate in intense magnetic fields but also areas with flammable gases where sparks could potentially cause an explosion.

We often say that a design is “fully” 3D printable, even though it might require screws or other bits of hardware. But in the case of the PneuAct, it’s truly all printed. It has to be, or else the whole thing would be ripped apart when it got to close to the MRI machine. Each and every piece of the motor is printed in ABS, and can be used without any additional machining or cleanup. No lubrication is required, and [Foad] mentions that the whole thing is so cheap that it can be disposable. Which is a huge advantage in medical environments where contamination could be a concern.

Design-wise the PneuAct is essentially an expanded version of the 3D printed air motors we’ve seen previously, but it would be fair to say that none has ever been studied so closely before.

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This Cetus Printer Is Rigged For Silent Running

July 26, 2018 by Dan Maloney 9 Comments

The entry-level 3D-printer market is a rich one, with offerings from many vendors that are surprisingly good. But nothing is perfect, and to hit the $200 price point some compromises are inevitable. That doesn’t mean you have to live with those engineering choices, of course, which makes these cheap printers a great jumping off point for aftermarket mods.

[Linas K] took this route and in the process made his Cetus 3D-printer essentially silent. The first part of the video below reviews the shortcomings of the stock machine and the mechanical changes [Linas] made, including new brackets for the Z-axis slide, relocating the WiFi antenna to someplace sensible, and adding limit switches for each slide. Inside the case, the electronics get a complete reworking, with a custom PCB to house Trinamic stepper drivers for ultraquiet operation. The new board also supports the limit switches as well as thermostatic control of the extruder fan and pads for a platform heater. As a bonus, the new PCB is much smaller than the original, leaving room to tuck the power supply into the case, which is a nice touch. It wasn’t cheap, and it meant basically gutting the printer, but the results are impressively quiet.

We’re tempted to try these silencing mods on our own Cetus, if [Linas] ever publishes the BOM and PCB designs (hint, hint). And Cetus hacking is becoming quite a thing around here. From a trio of Cetus pro-tips to turning a Cetus into a PCB machine, the little printer has a lot to offer.

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Juggling Machine Listens To The Bounce To Keep Ball In The Air

July 25, 2018 by Dan Maloney 10 Comments

It’s a seemingly simple task: bounce a ping-pong ball on a wooden paddle. So simple that almost anyone can pick up a ball and a paddle and make a reasonable job of it. Now, close your eyes and try to do it just by the sound the ball makes when it hits the paddle. That’s a little tougher, but this stepper-driven platform juggler manages it with aplomb.

That’s not to say that the path to the finished product in the video below was a smooth one for [tkuhn]. He went through multiple iterations over the last two years, including a version that surrounded the juggling platform with a fence of phototransistors to track where the ball was at any time. That drove four stepper motors through a cross-linkage that popped the platform up at just the right moment to keep the ball moving, and at just the right angle to nudge it back toward the center of the platform. The current version of the platform does away with the optical sensors in favor of four small microphones. The mics pick up the sharp, well-defined sound of the ball hitting the platform, process the signal through an analog circuit, and use that signal to trigger a flip-flop if the signal exceeds a setpoint. An Arduino then measures the time delay between arriving signals, calculates the ball’s position on the platform, and drives the steppers through a PID loop to issue the corrective bounce.

The video below is entrancing, but we found ourselves wishing for a side view of the action too. It’s an impressive build nonetheless, one that reminds us of the many maze-runner and Stewart platform robots we’ve seen.

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Carousel Of Cereals Mixes And Matches Custom Breakfast Blends

June 28, 2018 by Dan Maloney 10 Comments

There are those who reckon the humble bowl of breakfast cereal to be the height of culinary achievement. Look askance if you must, but cereal junkies are a thing, and they have a point. The magic comes not from just filling a bowl and adding a splash of milk, but by knowing which cereals to mix together.

Who needs all that fussy mixing, though, when you can automate and customize your cereal dispensing chores? That’s the approach [Kevin Obermann] and [Adrian Bernhart] took with their Cereal Dispensing Machine, even if they went a little further than necessary. Laser-cut plywood forms a four-station carousel for off-the-shelf dry-good dispensers, each of which got a stepper motor to replace the wrist-twisting. The original motors were a bit too wimpy to handle the more rugged morning selections and were eventually upgraded to gear motors. The platform that supports the dispensers also holds all the electronics, including an ESP32 to run everything and host the web app needed to choose your poison. Plus RGB LEDs, because breakfast should look like a rave. Sadly, the team ran out of GPIO pins and were unable to run the peristaltic pump needed to add the milk. There will always be version 2.0, though.

If cereal isn’t your automated breakfast of choice, we understand. Perhaps a more [Wallace] and [Gromit] style breakfast machine would do, or a robotic peanut butter sandwich any time of day is a treat.

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Simple Camera Slider Adds A Dimension Or Two To Your Shots

June 21, 2018 by Dan Maloney 5 Comments

Camera sliders are a popular build, and properly executed they can make for impressive shots for both time-lapse sequences or real-time action. But they seem best suited for long shots, as dollying a camera in a straight line just moves subjects close to the camera through the frame.

This slider with both pan and tilt axes can make moving close-ups a lot easier. With his extremely detailed build log, [Dejan Nedalkovski] shows how he went about building his with only the simplest of materials and tools. The linear rail is simply a couple of pieces of copper pipe supported by an MDF frame. The camera trolley rides the rails on common skateboard bearings and is driven by a NEMA-17 stepper, as are the pan and tilt axes. [Dejan] also provided a barn-door style pivot to tilt the camera relative to the rails, allowing the camera to slide up and down an inclined plane for really interesting shots. The controller uses an Arduino and a joystick to drive the camera manually, or the rig can be programmed to move smoothly between preset points.

This is a step beyond a simple slider and feels a little more like full-blown motion control. We’ve got a feeling some pretty dramatic shots would be possible with such a rig, and the fact that it’s a simple build is just icing on the cake.

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A CNC Plasma Cutter Table, From The Shop Floor Up

June 20, 2018 by Dan Maloney 2 Comments

Some projects are simple, some focus on precision and craftsmanship, and some are more of the quick-and-dirty variety. This home-built CNC plasma cutter table seems to follow a “go big or go home” philosophy, and we have to say we’re mighty impressed by the finished product.

For those who follow [Bob]’s “Making Stuff” YouTube channel, this build has been a long time coming. The playlist below has eight videos that cover the entire process from cutting the first tubes of the welded frame to the initial test cuts with the finished machine. [Bob] took great pains to make the frame as square and flat as possible, to the extent of shimming a cross member to correct a 0.030″ misalignment before welding. He used good-quality linear rails for each axis, and hefty NEMA 23 steppers. There were a few false starts, like the water pan that was going to be welded out of five separate pieces of steel until the metal shop guys saved the day with their press brake. In the end, the machine turned out great; with a build cost of $2000 including the plasma cutter it’s not exactly cheap, but it’s quite a bargain compared to similar sized commercial machines.

We think the video series is a great guide for anyone looking to make a CNC plasma table. We’ve seen builds like this before, including [This Old Tony]’s CNC router. Watching these builds gives us the itch to get into the shop and start cutting metal. Continue reading “A CNC Plasma Cutter Table, From The Shop Floor Up” →