2D Printed Tachometer For A Lathe

If you ever wanted a reason to have DC lighting pointed at the spinny part of your mill and lathe, [Bill] tells a great story. One day, he noticed the teeth on his lathe chuck would change color – red, then blue, then red. His conclusion was the fluorescent lights above his workbench was flashing, as fluorescent lights normally do.

Imagine if the teeth on [Bill]’s chuck weren’t painted. They would appear stationary. That’s usually a bad thing when one of the risks of using a lathe is ‘descalping.’ Buy an LED or incandescent work light for your shop.

This unique effect of blinking lights got [Bill] thinking, though. Could these fluorescent lights be used as a strobe light? Could it measure the RPM of the lathe?

And so began [Bill]’s quest for a 2D printed lathe tachometer. The first attempt was to wrap a piece of paper printed with evenly space numbers around the chuck. This did not work. The flash from his fluorescent bulb was too long, and the numbers were just a blur. He moved on to a maximum-contrast pattern those of us who had a ‘DJ phase’ might recognize immediately.

By printing out a piece of paper with alternating black and white bands, [Bill] was able to read off the RPM of his chuck with ease. That’s after he realized fluorescent lights blink twice per cycle, or 120 times a second. If you have a 3″ mini-lathe, [Bill] put the relevant files up, ready to be taped to a chuck.

Hackaday Prize Entry: Lose Yourself To Dance

Not every project for The Hackaday Prize needs to solve a pressing concern, save the planet, or help people. Sometimes, it just needs to be cool. [Jeremy]’s project is certainly cool. He’s building a touch-sensitive disco floor for the awesomeness of Saturday Night Fever combined with the technical complexity of the Billy Jean music video.

We’ve seen a few disco floor builds over the years, and for the most part, [Jeremy] isn’t straying too far from a well-tread path. He’s using LED strips to light his build, cutting the frame for the floor out of plywood and translucent squares, and using an ATMega to control each panel. So far, nothing out of the ordinary.

The trick to this build is that every square has a capacitive touch sensor. Underneath each translucent panel is a bit of wire mesh. Because the disco floor has 144 nodes, running the standard capacitive sensor library just wouldn’t work; the delay in measuring each node adds up very fast. By rewriting [Paul Stoffregen]’s capacitive sensor library, [Jeremy] was able to run many panels at once.

Right now [Jeremy] has a single panel that responds equally well to bare feet as it does to motorcycle boots. It’s exactly what you need in an interactive dance floor, and we can’t wait to seen the entire floor running.

The 2015 Hackaday Prize is sponsored by:

Astronaut Or Astronot: Amazingly Engineered

The latest round of community voting in The Hackaday Prize asked a simple question: which project is most likely to save the planet? The results will be posted on Monday.

Now it’s time to see if we’re giving away a $1000 gift card to the Hackaday Store, or just some prizes to people who have voted. The rules here are simple: I’m randomly selecting one person on Hackaday.io. if and only if that person has voted in the latest round of community voting, they get a thousand dollar gift card to the Hackaday store. If the randomly selected person did not vote, I select three people who have voted in the latest round of community voting. For the last few weeks, we’ve been giving out t-shirts. To sweeten the deal, we’re giving away a SmartMatrix, A Simon Says kit, and an Analog Stepper gauge to three people, just because they’ve voted.

Here’s the video:

Drat, the Hacker number randomly selected for the $1000 gift card hadn’t voted! Oh what could have been. Don’t let this happen to you next week, VOTE!

To soften the bitterness of defeat we dole out a few awesome prizes to those who had. [xanatos333] gets the Simon Says kit, [sylph.ds] gets an Analog Stepper Gauge, and [dougmsbbs] gets a Smartmatrix. Thanks to those who voted, and be sure to vote in the next round:


We’ll have to do some math and run a few scripts to figure out which projects the Hackaday.io community deemed most likely to save the planet. Until we put that data together, it’s time to start a new round of voting. This week, we’re looking for projects that are Amazingly Engineered.

Next Friday we’ll select a random person on Hackaday.io, and if they have voted, they get a $1000 gift card! For the apathetic non-voters… nada.

Color Light Painting With A 3D Printer

Light painting, or taking a few RGB LEDs, a camera with a long exposure, and turning the world into Tron, has been around for a while. We haven’t seen many people using their household CNC machines for the same effect. [ekaggrat] is the exception. He’s already used a 3D printer to do some light painting, and now he’s doing it in color.

This build is an extension of an earlier project we saw that used a white LED to draw pictures within the build volume of a delta printer. Just like the last time, [ekaggrat] wired LEDs up to a RAMPS board and toggled pins with the M42 command. This build merely triples the complexity of the wiring; the RGB LED is wired to pins 4,5, and 6 of the controller board, and the shutter release button of his camera is wired up to pin 11 with an optoisolator.

The ability to blink out Gcode is one thing, getting his two-year-old daughter to stand still for 3D scanning is another thing entirely. With the data in hand, [ekaggrat] was able to run this model through a script that would generate a light painting of his daughter. You can grab the script for that on GitHub, or check out the video below.

Continue reading “Color Light Painting With A 3D Printer”

New Part Day: STM32F7, An ARM Cortex-M7

It was announced last year, but ST is finally rolling out the STM32F7, the first microcontroller in production that is based on the ARM Cortex-M7.

The previous go-to part from the ST catalog was the STM32F4, an extremely powerful chip based on the ARM Cortex M4 processor. This chip was incredibly powerful in its time, and is still a respectable choice for any application that needs a lot of horsepower, but not a complete Linux system. We’ve seen the ~F4 chip pump out 800×600 VGA, drive a thermal imaging camera, and put OpenCV inside a webcam. Now there’s a new, even more powerful part on the market, and the mind reels thinking what might be possible.

Right now there a few STM32F7 parts out, both with speeds up to 216MHz, Flash between 512k and 1MB, and 320kB of RAM. Peripherals include Ethernet, USB OTG, SPDIF support, and I²S. The most advanced chip in the line includes a TFT LCD controller, and a crypto processor on-chip. All of the chips in the STM32F7 line are pin compatible with the STM32F4 line, with BGA and QFP packages available.

As with the introduction of all of ST’s microcontrollers, they’re rolling out a new Discovery board with this launch. It features Ethernet, a bunch of audio peripherals, USB OTG, apparently an Arduino-style pin layout, and a 4.3 inch, 480×272 pixel LCD with capacitive touch. When this is available through the normal distributors, it will sell for around $50. The chips themselves are already available from some of the usual distributors, for $17 to $20 in quantity one. That’s a chunk of change for a microcontroller, but the possibilities for what this can do are really only limited by an engineer’s imagination.

Android Donut Running On A Graphing Calculator

[Josh] is trying to fight a misconception that Android only runs on fast, powerful smartphones. He’s convinced Android will run on extremely low-end hardware, and after a great deal of searching, hit upon a great combination. He’s running Android Donut on a TI nSpire CX graphing calculator.

Unlike just about every other TI calculator, homebrew developers are locked out of the nSpire CX and CX CAS. Without the ability to run native applications on this calculator, [Josh] would be locked out of his platform of choice without the work of the TI calculator community and Ndless, the SDK for this series of calculators.

With the right development environment, [Josh] managed to get the full Android stack up and running and ironed the bugs out. Everything he’s done is available on the GitHub for this project, and with the instructions on the xda developers post, anyone can get a version of Android running on this TI calculator.

While [Josh] has Android Donut running along with most of the 1.6 apps, a terminal emulator, keyboard, WiFi, USB, and Bluetooth running, this calculator-come-Android isn’t as useful as you think it would be. The vast majority of calculator emulators on the Google Play store require Android version 2.2 and up. Yes, [Josh] can still run a TI-83 emulator on his calculator, but finding an app that’s compatible with his version of Android is a challenge.

Still, even with a 150MHz processor and 64MB of RAM – far less than what was found in phones that shipped with Donut – [Josh] is still getting surprisingly good performance out of his calculator. He can play some 2D games on it, and the ability to browse the web with a calculator is interesting, to say the least. It is, however, the perfect example that you don’t need the latest and greatest phone to run Android. Sometimes you don’t even need a phone.

Hackaday Prize Entry: Biohand

One of the greatest uses we’ve seen for 3D printing is prosthetics; even today, a professionally made prosthetic would cost thousands and thousands of dollars. For his entry to the Hackaday Prize, [Martin] is building a low-cost 3D printed hand that works just like a natural hand, but with motors instead of muscles and tendons.

There are a lot of 3D printed finger mechanisms around that use string and wires to move a finger around. This has its advantages: it’s extremely similar to the arrangement of tendons in a normal hand, but [Martin] wanted to see if there was a better way. He’s using a four-bar linkage instead of strings, and is driving each finger with a threaded rod and servo motor. It’s relatively strong; just the motor and drive screw system was able to lift 1kg, and this mechanical arrangement has the added bonus of using the servo’s potentiometer to provide feedback of the position of the finger to the drive electronics.

This is far from the only prosthetic hand project in the running for The Hackaday Prize. [OpenBionics] is working on a very novel mechanism to emulate the function of the human hand in their project, and [Amadon Faul] is going all out and casting metacarpals and phalanges out of aluminum in his NeoLimb project. They’re all amazing projects, and they’re all making great use of 3D printing technology, and by no means are there too many prosthetic projects entered in The Hackaday Prize.

The 2015 Hackaday Prize is sponsored by: