A Stepper Motor for Two Dimensions

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.

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A cortex M4 based platform with ETH, USB, BT and many on-board peripherals

Here is a very time consuming project that I worked on during last summer: an ARM Cortex M4 based platform with plenty of communication interfaces and on-board peripherals. The particular project for which this board has been developed is not really HaD material (one of my father’s funny ideas) so I’ll only describe the platform itself. The microcontroller used in the project is the ATSAM4E16C from Atmel, which has 1Mbyte of flash and 128Kbytes of SRAM. It integrates an Ethernet MAC, a USB 2.0 Full-speed controller, a sophisticated Analog to Digital Converter and a Digital to Analog Converter (among others).

Here is a list of the different components present on the board so you can get a better idea of what the platform can do: a microphone with its amplifier, a capacitive touch sensor, two unipolar stepper motors controllers, two mosfets, a microSD card connector, a Bluetooth to serial bridge, a linear motor controller and finally a battery retainer for backup power. You can have a look at a simple demonstration video I made, embedded after the break. The firmware was made in C and uses the Atmel Software Framework. The project is obviously open hardware (Kicad) and open software.

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Building a linear motor

linear-motor

We admit that this project doesn’t have very many details available, but it was just too neat for us to pass up. It’s a small linear motor which [ligonapProduktion] built after seeing a very brief description of a commercially available version.

The video after the break shows him testing the motor. In this screenshot he’s holding the center shaft while the coil assembly moves back and forth. But it works with a stationary coil moving the rod as well. The motor is basically a modified solenoid. There are sixteen neodymium magnets inside the shaft. The set of four coils is driven by an ATtiny44. Just like a stepper motor, energizing the coils in the correct order pushes against the rare earth magnets creating motion.

We’re not sure if he has any use in mind for this build. For us we just like to see the concept in practice (we feel the same way about a homopolar motor build).

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Semi-automatic PCB drill press

Kiss the days of breaking bits while drilling through-hole PCBs goodbye thanks to this semi-automatic drill press (translated). Now it’s not going to line up the bit with the exact location of the hole (that would make it a fully automatic drill press). This works by lining up the board manually, then stepping on a pedal to activate the plunging motion of the drill.

A linear motor is responsible for the smooth, accurate motion along the Z-axis. Many hobby setups use a Dremel drill press, or even rely on prayer-based systems such as doing it free-hand with a rotary tool or by using a piece of acrylic as a guide hole. The hobby drill press tends to have some play in it and free-handing with tiny bits that are as fragile as glass both result in far too many broken drill bits. In the video after the break you can see that the linear motion is perfectly plumb with the table of the device, preventing the movements that cause breakage. The addition of the pedal makes it easy to position the boards because you can use both hands.

Having a tool like this takes all of the frustration out of using through-hole parts.

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