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Hackaday Links: January 25, 2015

January 25, 2015 by 24 Comments

Misumi is doing something pretty interesting with their huge catalog of aluminum extrusions, rods, bolts, and nuts. They’re putting up BOMs for 3D printers. If you’ve ever built a printer with instructions you’ve somehow found on the RepRap wiki, you know how much of a pain it is to go through McMaster or Misumi to find the right parts. Right now they have three builds, one with linear guides, one with a linear shaft, and one with V-wheels.

So you’re finally looking at those fancy SLA or powder printers. If you’re printing an objet d’arte like the Stanford bunny or the Utah teapot and don’t want to waste material, you’re obviously going to print a thin shell of material. That thin shell isn’t very strong, so how do you infill it? Spheres, of course. By importing an object into Meshmixer, you can build a 3D honeycomb inside a printed object. Just be sure to put a hole in the bottom to let the extra resin or powder out.

Remember that episode of The Simpsons where Homer invented an automatic hammer? It’s been reinvented using a custom aluminum linkage, a freaking huge battery, and a solenoid. Next up is the makeup shotgun, and a reclining toilet.

[Jan] built a digitally controlled analog synth. We’ve seen a few of his FM synths VA synths built from an LPC-810 ARM chip before, but this is the first one that could reasonably be called an analog synth. He’s using a digital filter based on the Cypress PSoC-4.

The hip thing to do with 3D printers is low-poly Pokemon. I don’t know how it started, it’s just what the kids are doing these days. Those of us who were around for Gen 1 the first time it was released should notice a huge oversight by the entire 3D printing and Pokemon communities when it comes to low-poly Pokemon. I have corrected this oversight. I’ll work on a pure OpenSCAD model (thus ‘made completely out of programming code’) when I’m sufficiently bored.

*cough**bullshit* A camera that can see through walls *cough**bullshit* Seriously, what do you make of this?

CNCs And Acrylic And LEDs Oh My!

January 25, 2015 by 11 Comments

Looking for something unique to spice up his music room [Est] decided he wanted to try making a light that responds to the music — kind of like a VU meter, but a little different. He calls it the Light Effect Tower.

The main structure of the tower was cut out of 6mm acrylic using [Est’s] homemade CNC router. He used a V router bit to do the engraving, which when combined with light, produces a high contrast dynamic with the plastic.

He designed the circuit to fit into the triangular base, which uses a PIC micro controller to sample a microphone to produce the lighting effect. The cool thing is, he’s designed it to calculate the max level of noise, to scale the sample accordingly — that way if you’re playing loud music or quiet music, it’ll still work without any adjustments to the microphone gain.

Oh yeah, did we mention this thing is big? It’s actually 1.5 meters tall! Check out the different modes he programmed in — it’s pretty bumping.

Continue reading “CNCs And Acrylic And LEDs Oh My!” →

CoreXY For A Dry Erase Plotter

January 25, 2015 by 45 Comments

After years of playing DnD, it’s finally [Mike]’s turn to be a DM. Of course he can’t draw maps with his hands, so that means building a tabletop plotter.

[Mike] is basing his tabletop game plotter on the Makelangelo, a polar plotter that draws images on a vertical platform with the help of two motors in the corner. This is a tabletop plotter, so the usual vertical arrangement wouldn’t work, but there are some projects out there that use the CoreXY system for a similar horizontal build.

The tabletop CoreXY system is built from rigid aluminum yard sticks, 3D printed parts, two very cheap stepper motors, an Arduino, and a whole lot of string. It’s a very inexpensive build and because [Mike] is using metal rulers for the frame, it’s also very low profile – a nice advantage for table top sessions.

So far, [Mike] has the axes of the plotter moving, with a servo and pen mechanism next on the build plan. He has a few neat ideas for how to plot these dungeon maps by vectoring bitmap images and sending them to the Arduino, something we’ll probably see in a an upcoming build log.

You can check out a video of [Mike]’s build below.

Continue reading “CoreXY For A Dry Erase Plotter” →

Making Membrane Keypads From Scratch

January 25, 2015 by 28 Comments

A few years ago, [Paul]’s son got a simple electronic toy that plays funny noises and sings to him. The son loves the toy, but after months and months of use, the toy was inevitably broken beyond repair. Figuring an ‘electronic box that plays sounds’ wouldn’t be a hard project to replicate, [Paul] set out on making his own. The electronics weren’t hard, but custom membrane keypads are hard to come by. No matter, because it’s actually pretty easy to build your own.

Membrane switches are usually made with silkscreen conductive inks on fancy plastic, but that’s not a requirement to build your own. All you really need are four layers – a ‘front decal’, a ‘top foil’ layer for the rows, a ‘bottom foil’ layer for the columns, and a ‘cutout’ layer that provides enough separation between the rows and columns.

[Peter] laid out the four layers in Illustrator, printed the layers, and covered the rows and columns with copper tape. The cutout layer is the crucial part that keeps the layers separated until the button is pressed, and that was just a piece of card stock with strategically placed holes.

Once the rows, columns, and other layers were glued up, [Peter] could connect this keypad up to a microcontroller. The code is very easy with the Arduino keypad library, and should stand up to the rigors of being handled by a child.

“Scotty” Is More Hungry 3D-printing Fax Machine Than Teleporter

January 25, 2015 by 40 Comments

Researchers at the Hasso Plattner Institute have created “Scotty,” a so-called teleportation system. While the name is a clear homage to the famous Star Trek character, this is not the Sci-Fi teleporting you may be expecting. The system is composed of two 3D printers (they used a pair of MakerBot Replicators). The “sender” printer has a camera and built-in milling machine. It uses deconstructive scanning – taking the picture of an object’s layer, then grinding that layer down to expose the next layer – and then sends the encrypted data to a “receiver” printer with a RasPi to decrypt the data so that it can immediately print the object. The ultimate idea behind this is that there is only one object at the end of the process.

It’s a disservice describing Scotty as a teleporter. By the researchers’ definition of a teleporter, the lowly fax machine is on par with Scotty – and it doesn’t destroy the original. The researchers claim that this destructive-reconstuctive method preserves the uniqueness of a given object, as long as any sentimentality. We can agree with the unique aspect: the less copies of something means it retains it intrinsic value in the marketplace. The sentimentality – not so much. We’ve all had a moment in our lives where a treasured item of ours, worthless to everyone else, was destroyed. Either we’d get a replacement or someone else would give us one to silence our wailing, but it wasn’t quite the same. If you could clone your dead pet, subconsciously you’d know it’s not going to be the same Fluffy. It’s that exact thing, atoms and all, that has the emotional attachment. Trying to push that psychological perspective onto Scotty’s purpose is irksome.

Continue reading ““Scotty” Is More Hungry 3D-printing Fax Machine Than Teleporter” →

When Adding Noise Helps

January 25, 2015 by 20 Comments

It’s a counterintuitive result that you might need to add noise to an input signal to get the full benefits from oversampling in analog to digital conversion. [Paul Allen] steps us through a simple demonstration (dead link, try Internet Archive) of why this works on his blog. If you’re curious about oversampling, it’s a good read.

Oversampling helps to reduce quantization noise, which is the sampling equivalent of rounding error. In [Paul’s] one-bit ADC example, the two available output values are zero volts and one volt. Any analog signal between these two values is rounded off to either zero or one, and the resulting difference is the quantization error.

In oversampling, instead of taking the bare minimum number of samples you need you take extra samples and average them together. But as [Paul] demonstrates, this only works if you’ve got enough noise in the system already. If you don’t, you can actually make your output more accurate by adding noise on the input. That’s the counterintuitive bit.

We like the way he’s reduced the example to the absolute minimum. Instead of demonstrating how 16x oversampling can add two bits of resolution to your 10-bit ADC, it’s a lot clearer with the one-bit example.

[Paul’s] demo is great because it makes a strange idea obvious. But it got us just far enough to ask ourselves how much noise is required in the system for oversampling to help in reducing quantization noise. And just how much oversampling is necessary to improve the result by a given number of bits? (The answers are: at least one bit’s worth of noise and 22B, respectively, but we’d love to see this covered intuitively.) We’re waiting for the next installment, or maybe you can try your luck in the comment section.

Atari CNC Pendant

Atari 2600 Controller Now Controls CNC Plasma Cutter

January 24, 2015 by 15 Comments

When using any CNC machine the system has to understand where the part to be machined is physically located. This is most commonly done by jogging the tool to a position relative to the part and then indicating to the controller that the tool is indeed at that position. Hobby CNC enthusiasts [Jeremy] and [Yakob] wanted an easy, convenient (and even fun) way to zero their plasma cutter. They decided to make a wireless jog pendant capable of moving and zeroing their machine….. and it’s built into a retro game controller!

The housing is a wireless Atari 2600 controller. Most of the innards were taken out and replaced with a BlueFruit EZ-Key module that takes input signals from the stock joystick and button switches and, in turn, emulates a Bluetooth keyboard signal that is understood by a PC. Most PC-based CNC Control Software’s have keyboard shortcuts for certain functions. This project takes advantage by using those available keyboard shortcuts by mapping individual pin inputs to specific keyboard key presses.

The X and Y axes are controlled by pushing the joystick in the appropriate direction. Pressing the ‘fire’ button zeros the axis. Even though the remote is working now, these two guys want to add a rotary encoder so that they can make minor Z axis height adjustments on the fly since sometimes the metal they are plasma cutting isn’t completely flat.

If you’re interested in making CNC Pendants out of old tech, check out this once-was TV remote.