stepper

166 Articles

Smooth stepper motor robot arm

Stepper Motor Robot Arm Has Smooth Moves

January 22, 2018 by 17 Comments

[Tobias Kuhn] had watched a YouTube video about a robot arm which used servo motors, and wanted to try making one himself. But he found it hard to get slow or smooth movements out of the servos. Even removing the microcontroller and trying to work with the servo’s driver-IC and potentiometer from an Arduino Nano didn’t get him satisfaction.

Then he found the very affordable 28BYJ-48 stepper motor. After some experimenting, he came up with a smooth moving robot arm with four steppers controlled from an Arduino Mega and A4988 stepper motor drivers. Rather than write a bunch of stepper motor code himself, he installed and ran a four-axis fork of grbl on the Arduino, turning it into a stepper motor controller. One minor hitch was that the A4988 motor drivers are for bipolar stepper motors but 28BYJ-48 steppers are unipolar. Luckily he knew of a very simple hack which our [Brian Benchoff] wrote about for turning a unipolar motor into a bipolar motor.

To tell the robot arm what to do, he built a replica arm with potentiometers in place of the stepper motors. As he manipulates the replica, the values of the potentiometers are read by a Raspberry Pi and some custom Python code which sends the appropriate G-code to the Arduino/grbl controlled robot arm. There’s a bit of a lag but when he moves the replica arm, the robot arm does the same move. See it in action in the video below.

Continue reading “Stepper Motor Robot Arm Has Smooth Moves” →

Cable Cutting Machine Makes Fast Work Of A Tedious Job

January 14, 2018 by 22 Comments

We’ve all been there: faced with a tedious job that could be knocked out manually with a modest investment of time, we choose instead to overcomplicate the task and build something to do it for us. Such was the impetus behind this automated wire cutter, but in this case the ends justify the means.

That [Edward Carlson] managed to stretch a twenty-minute session with wire cutters and a tape measure into four days of building and tweaking this machine is pretty impressive. The build process was jump-started by modifying an off-the-shelf wire measuring machine, of the kind one finds in the electrical aisle of The Big Orange Store. Stripped of the original mechanical totalizer and with a stepper added to drive the friction wheels, the machine can now measure cable by counting steps. A high-torque servo drives a stout pair of cable shears through a nifty linkage, or the machine can just measure the length of cable without cutting. [Edward]’s solution in search of a problem ends up bringing extra value, so maybe the time spent was worth it after all.

If the overall design looks familiar, you may be thinking of a similar of another cable-cutting bot we featured a while back. That one used a filament extruder and was for lighter gauge wires than this machine. Continue reading “Cable Cutting Machine Makes Fast Work Of A Tedious Job” →

A Stepper Motor For Two Dimensions

January 8, 2018 by 47 Comments

We’ve all heard linear motors, like those propelling Maglev trains, described as “unrolled” versions of regular electric motors. The analogy is apt and helps to understand how a linear motor works, but it begs the question: what if we could unroll the stator in two dimensions instead of just one?

That’s the idea behind [BetaChecker’s] two-axis stepper motor, which looks like it has a lot of potential for some interesting applications. Build details are sparse, but from what we can gather from the videos and the Hackaday.io post, [BetaChecker] has created a platen of 288 hand-wound copper coils, each of which can be selectively controlled through a large number of L293 H-bridge chips and an Arduino Mega. A variety of sleds, each with neodymium magnets in the base, can be applied to the platen, and depending on how the coils are energized, the sled can move in either dimension. For vertical applications, it looks like some coils are used to hold the sled to the platen while others are used to propel it. There are RGB LEDs inside the bore of each coil, although their function beyond zazzle is unclear.

We’d love more details to gauge where this is going, but with better resolution, something like this could make a great 3D-printer bed. If one-dimensional movement is enough for you, though, check out this linear stepper motor that works on a similar principle.

Continue reading “A Stepper Motor For Two Dimensions” →

Balance Like A Mountain Goat On This Simple Stewart Platform

December 27, 2017 by 4 Comments

No goats were harmed in the making of this 3-DOF Stewart platform for [Bruce Land]’s microcontrollers course at Cornell.

If the name “Stewart platform” doesn’t ring a bell, the video below will help you out. [Team Microgoats] built a small version of the mechanical system commonly seen in flight simulators, opting for 3 DOF  to simplify the design. Their PIC32-controlled steppers can wobble and weave the table in response to inputs from an MPU-6050 six-axis accelerometer embedded in the base of a 3D-printed goat. Said goat appears to serve no other role in the build, but goats are cool, so why not? And if you’ve ever seen a mountain goat frolicking across a sheer vertical rock face like it was walking across a parking lot, you’ll understand the connection to the balance and control offered by a Stewart platform.

[Bruce Land]’s course is always a bonanza of neat projects that pop up in our tipline this time of year, like a POV box fan, a coin cell Rickrolling throwie, and a dynamometer for small electric motors.

Continue reading “Balance Like A Mountain Goat On This Simple Stewart Platform” →

Old Scanner Finds New Life In DIY PCB Fab

December 20, 2017 by 32 Comments

Cheap, high-quality PCBs are truly a wonder of our age. That a professionally fabricated board with silkscreen and solder mask can be ordered online and delivered to your door has lowered the bar between a hobbyist project and a polished product. But the wait can be agonizing, and it can throw a wrench into the iterative design process. What to do?

[Andras Kabai] knows the answer to that, and this former flatbed scanner turned into a UV exposer is the centerpiece of his DIY board fab. The old Mustek scanner was a couple of bucks secondhand, and provided not only the perfect form-factor for a board scanner but a trove of valuable parts to reuse. [Andras] replaced the original fluorescent light bar with a long, narrow PCB stuffed with UV LEDs, and added an Arduino Mega to control the original stepper drive. The project looks like it went through a little feature creep, with an elaborate menu system and profiles that include controls for exposure time, the brightness of the LED array via PWM, and the length of board that gets exposed. It’s clearly a work in progress, but early results are encouraging and we’ll be watching to see how [Andras]’ in-house fab shapes up.

This approach to PCB fab is only one of many, of course. You can turn a budget 3D-printer into a PCB machine, or even use an LCD to mask the boards during exposure. The latter intrigues us — an LCD mask and a scanning UV light source could make for a powerful PCB creation tool.

Poor Man’s Laser Scanner Probably Won’t Shoot Your Eye Out, Kid

December 16, 2017 by 13 Comments

Yes, laser cutters that come off the slow boat from China are more affordable than ever, and with some tweaks and hacks they can turn out some decent results. But if you just want a laser lightshow that’ll draw boxes on your living room ceiling, this simple X-Y laser scanner might be a good platform to build.

Let’s say right up front that there are more than a few safety issues with [ThingEngineer]’s 3D-printed two-axis scanner. He’s well aware of these potential retina-cooking issues and duly notes that a good pair of laser safety goggles is a must and that the cheap anti-lawsuit glasses that laser module manufacturers often include with their products don’t count.

[Editor’s Note: Glasses are really only intended for alignment operations. Pros enclose lasers beyond a certain power to prevent anyone going blind. Know where your beam terminates, kids.]

With that in mind, there’s a lot to be said for this poor man’s scanner build. Yes, it would be faster with real galvos and low-mass mirrors, but time is money, and the steppers and craft store mirror discs do the job, albeit slowly. We like that everything is so simple, even the method for turning a regular mirror into a front-surface mirror.

[ThingEngineer] proves you don’t need galvanometers to have some simple laser fun. And if steppers don’t do it for you, you can try little brushed DC hobby motors or even 3D-printed cams.

Continue reading “Poor Man’s Laser Scanner Probably Won’t Shoot Your Eye Out, Kid” →

Start Tracking Satellites With This Low-Cost Azimuth-Elevation Positioner

November 26, 2017 by 28 Comments

Tracking satellites and the ISS is pretty easy. All you really need is an SDR dongle or a handheld transceiver, a simple homebrew antenna, and a clear view of the sky. Point the antenna at the passing satellite and you’re ready to listen, or if you’re a licensed amateur, talk. But the tedious bit is the pointing. Standing in a field or on top of a tall building waving an antenna around gets tiring, and unless you’re looking for a good arm workout, limits the size of your antenna. Which is where this two-axis antenna positioner could come in handy.

While not quite up to the job it was originally intended for — positioning a 1.2-meter dish antenna — [Manuel] did manage to create a pretty capable azimuth-elevation positioner for lightweight antennas. What’s more, he did it on the cheap — only about €150. His design seemed like it was going in the right direction, with a sturdy aluminum extrusion frame and NEMA23 steppers. But the 3D-printed parts turned out to be the Achille’s heel. At the 1:40 mark in the video below (in German with English subtitles), the hefty dish antenna is putting way too much torque on the bearings, delaminating the bearing mount. But with a slender carbon-fiber Yagi, the positioner shines. The Arduino running the motion control talks GS232, so it can get tracking data directly from the web to control the antenna in real time.

Here’s hoping [Manuel] solves some of the mechanical issues with his build. Maybe he can check out this hefty dish positioner for weather satellite tracking for inspiration.

Continue reading “Start Tracking Satellites With This Low-Cost Azimuth-Elevation Positioner” →