New Part Day: Silent Stepper Motors

Some of the first popular printers that made it into homes and schools were Apple Imagewriters and other deafeningly slow dot matrix printers. Now there’s a laser printer in every office that’s whisper quiet, fast, and produces high-quality output that can’t be matched with dot matrix technology.

In case you haven’t noticed, 3D printers are very slow, very loud, and everyone is looking forward to the day when high-quality 3D objects can be printed in just a few minutes. We’re not at the point where truly silent stepper motors are possible just yet, but with the Trinamic TMC2100, we’re getting there.

Most of the stepper motors you’ll find in RepRaps and other 3D printers are based on the Allegro A498X series of stepper motor drivers, whether they’re on breakout boards like ‘The Pololu‘ or integrated on the control board like the RAMBO. The Trinamic TMC2100 is logic compatible with the A498X, but not pin compatible. For 99% of people, this isn’t an issue: the drivers usually come soldered to a breakout board.

There are a few features that make the Trinamic an interesting chip. The feature that’s getting the most publicity is a mode called stealthChop. When running a motor at medium or low speeds, the motor will be absolutely silent. Yes, this means stepper motor music will soon be a thing of the past.

However, this stealthChop mode drastically reduces the torque a motor can provide. 3D printers throw around relatively heavy axes fairly fast when printing, and this motor driver is only supposed to be used at low or medium velocities.

The spreadCycle feature of the TMC2100 is what you’ll want to use for 3D printers. This mode uses two ‘decay phases’ on each step of a motor to make a more efficient driver. Motors in 3D printers get hot sometimes, especially if they’re running fast. A more efficient driver reduces heat and hopefully leads to more reliable motor control.

In addition to a few new modes of operation, the TMC2100 has an extremely interesting feature: diagnostics. There are pins specifically dedicated as notification of shorted outputs, high temperatures, and undervolt conditions. This is something that can’t be found with the usual stepper drivers, and it would be great if a feature like this were to ever make its way into a 3D printer controller board. I’m sure I’m not alone in having a collection of fried Pololu drivers, and properly implementing these diagnostic pins in a controller board would have saved those drivers.

These drivers are a little hard to find right now, but Watterott has a few of them already assembled into a Pololu-compatible package. [Thomas Sanladerer] did a great teardown of these drivers, too. You can check out that video below.

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Drawing On Glow In The Dark Surfaces With Lasers

What do you get when you have a computer-controlled laser pointer and a big sheet of glow in the dark material? Something very cool, apparently. [Riley] put together a great build that goes far beyond a simple laser diode and servo build. He’s using stepper motors and a proper motion control software for this one.

The theory behind the device is simple – point a laser at some glow in the dark surface – but [Riley] is doing this project right. Instead of jittery servos, the X and Y axes of the laser pointer are stepper motors. These are controlled by an Arduino Due and TinyG motion control software. This isn’t [Riley]’s first rodeo with TinyG; we saw him at Maker Faire NYC with a pendulum demonstration that was absolutely phenomenal.

Right now, [Riley] is taking SVG images, converting them to Gcode, and putting them up on some glow in the dark vinyl. Since the Hackaday Skull ‘n Wrenches is available in SVG format, that was an easy call to make on what to display in weird phosphorescent green. You can see a video of that along with a few others below.

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An MSP430-based Automatic Fish Feeder

[Dmitri] wanted to buy an automatic feeding setup for his aquarium, but he found that most off-the-shelf feeders are really inaccurate with portion control. [Dmitri]’s fish is sensitive to overfeeding, so an off-the-shelf feeder wouldn’t get the job done. Since [Dmitri] knows a thing or two about electronics, he set out to build his own microcontroller-based automatic feeding machine.

[Dmitri]’s machine is based around a MSP430 that starts feeding at scheduled times and controls how much food is dispensed. The MSP lives on a custom PCB that [Dmitri] designed, which includes a stepper motor driver and input for an endstop sensor. The board is wired to a stepper motor that advances a small wooden board with a series of holes in it. Each hole is filled with a single serving of food. The board slides along a piece of U-channel, and food drops out of each hole into the aquarium when the hole reaches the end of the channel.

The whole build is very well documented, and [Dmitri] explains each block of his schematic in detail. His firmware is also open-source, so you can build your own fish feeder based off of his design. Check out the video after the break to see the feeder in action.

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3D-Printed Clock Tells Time with Gears

[ekaggrat] designed a 3d-printed clock that’s fairly simple to make and looks awesome. The clock features a series of 3d-printed gears, all driven by a single stepper motor that [ekaggrat] found in surplus.

The clock’s controller is based around an ATtiny2313 programmed with the Arduino IDE. The ATtiny controls a Darlington driver IC which is used to run the stepper motor. The ATtiny drives the stepper motor forward every minute, which moves both the hour and minute hands through the 3d-printed gears. The hour and minute are indicated by two orange posts inside the large gears.

[ekaggrat] etched his own PCB for the microcontroller and stepper driver, making the build nice and compact. If you want to build your own, [ekaggrat] posted all of his design files on GitHub. All you need is a PCB (or breadboard), a few components,  and a bit of time on a 3D printer to make your own clock.

Timelapse Photography on an Android-Powered Dolly

camera dolly

If you’re heading off on a trip to Alaska, you need to make sure you have plenty of supplies on hand for the wilderness that awaits. If you’re [Bryce], that supply list includes some interesting photography equipment, including a camera dolly that he made to take time-lapse video of the fantastic scenery.

On the hardware side, the dolly carries the camera on a rail that is set up on a slant. The camera starts on one side and moves up and towards the otherside which creates a unique effect in the time-lapse. The rig is driven by a stepper motor, and rides on some pretty fancy bearings. The two cameras [Bryce] plans to use are a Canon T2i and a EOS-M which sit on the top from a tripod.

The software and electronics side is interesting as well. Instead of the usual Arduino, [Bryce] opted for controlling the rig through Android and a IOIO board. This gives the project a lot of options for communications, including Bluetooth. The whole thing is powered by a 19V battery pack. If you’re looking for something a little simpler, you might want to check out the egg timer for time lapse! Check out the video of [Bryce]’s rig in action after the break.

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Sweet Stepper of [Jeremy]’s Rocks Out with its Box Out

Inspired by the floppy drive orchestras of others, [Jeremy] has built a Pi-driven MIDI music box with stepper motor resonators and outlined the build on hackaday.io.

Control for the motors comes from an Iteaduino Mega 2560. The music starts as a MIDI file, gets processed into a text file, and is played over serial by a Raspberry Pi. He’s added percussion using K’NEX instruments and 9g servos, which we think is a nice touch. It can be powered via LiPo or from the wall, and [Jeremy] baked in protection against blowing up the battery. As he explains in the tour video after the break, the box is clamped to a wooden table to provide richer sound.

[Jeremy]’s favorite part of the build was enclosing the thing as it was his first time using panel-mount components. Stick around to see a walk-through of the guts and a second video demonstrating its musical prowess.

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Changing Unipolar Steppers To Bipolar

steppers

If you’ve been a good little hacker and have been tearing apart old printers like you’re supposed to, you’ve probably run across more than a few stepper motors. These motors come in a variety of flavors, from the four-wire deals you find in 3D printer builds, to motors with five or six wires. Unipolar motors – the ones with more than four wires – are easier to control, but are severely limited in generating torque. Luckily, you can use any unipolar motor as a more efficient bipolar motor with a simple xacto knife modification.

The extra wires in a unipolar motor are taps for each of the coils. Simply ignoring these wires and using the two coils independently makes the motor more efficient at generating torque.

[Jangeox] did a little experiment in taking a unipolar motor, cutting the trace to the coil taps, and measuring the before and after torque. The results are impressive: as a unipolar motor, the motor has about 380 gcm of torque. In bipolar mode, the same motor has 800 gcm of torque. You can check that video out below.

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