Active Aero For A Radio Control Car

January 3, 2021 by 12 Comments

Motorsport became obsessed with aerodynamics in the middle of the 20th century. Moving on from simple streamlined shapes, designers aimed to generate downforce with wing elements in order to get more grip between the tyres and the track. This culminated in the development of active aero, where wing elements are controlled by actuators to adjust the downforce as needed for maximum grip and minimum drag. Recently, [Engineering After Hours] decided to implement the technology on his Traxxas RC car.

The system consists of a simple multi-element front wing, chosen for its good trade-off between downforce and drag. The wing is mounted to a servo, which varies the angle of attack as the car’s pitch changes, as detected by a gyroscope. As the car pitches up during acceleration, the angle of the wing is increased to generate more downforce, keeping the nose planted.

The basic concept is sound, though as always, significant issues present themselves in the implementation. Small bumps cause the system to over-react, folding the wing under the front wheels. Additionally, the greater front downforce caused over-steer, leading to the install of a rear wing as well for better aero balance.

Regardless of some hurdles along the way, it’s clear the system has potential. We look forward to the next build from [Engineering After Hours], which promises to mimic the fan cars of the 70s and 80s. If you’re looking to improve aero on your full-size car, we’ve got a guide to that too. Video after the break.

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Vintage Meters Reborn As Steam Punk Clock

January 3, 2021 by 30 Comments

[Build Comics], purveyors of comic strips “where tools are heroes”, have saved another pair of old, vintage, analog meters from the junkyard by converting them into a Meter Clock. The real heroes of the story are their trusty tools – Mac X the knife, Mr. TS the table saw and his trusty band of clamps, G. Rinder the angle grinder, Weldy the welder, Sharp Eye the marker, rounded up by Sandy the Sander and Jiggy Saw. The Drake & Gorham (London) meters going under the knife appear similar to vintage hardware from just after the end of World War II, such as this Ferranti Ammeter found at the Science Museum Group, making them at least 75 years old.

A small cam is used to engage the DST switch.

As you might expect, the conversion process is reminiscent of their previous projects. The original moving-coil movements are discarded, and the pointer is attached to a servo which will act as the new movement. Fresh dials are prepared to replace the original ampere markings with hours and minutes. To retain some of the original charm, the new dials have discoloration and blemishes replicated from the old dials.

The set screw which was once used to align the pointer with the zero mark on the dial is now used to activate a micro switch that enables daylight savings time. Two additional buttons provide a convenient interface to adjust the time. Precision time signals are derived from a DS3231 RTC module connected to an Arduino. A pair of seven segment displays are connected to the Arduino to make it easier to set the time. A piece of oak plank, surrounded by a metal angled frame, is used as a base for mounting the two meters so that the clock can be hung up on the wall.

If you’d like to build some more vintage inspired instrumentation, [Build Comics] have you covered with a Classy Weather Display or a Plant Moisture Gauge.

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Dog Bowls Show The Versatility Of Ceramic Slip Casting

January 3, 2021 by 18 Comments

Here at Hackaday, we feature projects that are built of just about every material imaginable. Silicon-spangled fiber-reinforced epoxy resin is our primary medium, but we see plastic, wood, steel, aluminum, and even textiles from time to time. It’s not often we see slip-cast ceramic molding, though, and when it pops up, it’s always good to take a look at this versatile manufacturing method.

The back-story on this one is that [thoughtfulocean], a mechanical engineer idled by COVID lockdowns, wanted custom water bowls for his dogs, one of whom is clearly a grumpy Ewok. The design started with a 3D-print of the final vessel, printed in sections and glued together. These were used to create a two-piece plaster mold into which a watery slurry of clay, or slip, was poured. The plaster mold dehydrates the slip, leaving behind a semi-solid layer of clay of the desired thickness once the excess slip is poured off. The resulting casting is then fired in a kiln and glazed.

Of course, [thoughtfulocean] ran into a few problems along the way. The first mold was warped thanks to the mold box bowing under pressure from the plaster, so the whole molding process had to be revamped. The finished bowl also shrunk less than expected after firing, which led to some more revisions. But the finished bowl look really nice, and the included pump and filter keeps the Ewok’s water free from the yuck a dog’s face can introduce. As a bonus, it sounds like [thoughtfulocean] might have created a marketable product from all this. Take that, COVID!

Slip-casting ceramic may not be all that common around here, but ceramic as a material isn’t exactly a stranger. And who says slip casting is limited to ceramic? After all, we’ve seen a similar method used with plastic resin.

[via r/engineering]

An Arduino And A CD-ROM Drive Makes A CD Player

January 3, 2021 by 49 Comments

In an age of streaming media it’s easy to forget the audio CD, but they still remain as a physical format from the days when the “Play” button was not yet the “Pay” button. A CD player may no longer be the prized possession it once was, but it’s still possible to dabble in the world of 120 mm polycarbonate discs if you have a fancy for it. It’s something [Daniel1111] has done with his Arduino CD player, which uses the little microcontroller board to control a CD-ROM drive via its IDE bus.

The project draws heavily from the work of previous experimenters, notably ATAPIDUINO, but it extends them by taking its audio from the drive’s S/PDIF output. A port expander drives the IDE interface, while a Cirrus Logic WM8805 S/PDIF transceiver handles the digital audio and converts it to an I2S stream. That in turn is fed to a Texas Instruments PCM5102 DAC, which provides a line-level audio output. All the code and schematic can be found in a GitHub repository.

To anyone who worked in the CD-ROM business back in the 1990s this project presses quite a few buttons, though perhaps not enough to dig out all those CDs again. It would be interesting to see whether the I2S stream could be lifted from inside the drive directly, or even if the audio data could be received via the IDE bus. If you’d like to know a bit more about I2S , we have an article for you.

Blackboard Becomes Tidy Pen Plotter

January 3, 2021 by 7 Comments

Printers are all well and good, but they’re generally limited to smaller paper sizes and use expensive ink. If you instead want to produce art on a larger scale, a plotter can be a great way to go. [tuenhidiy] built a tidy example using an old blackboard as a base.

These days, such a build is quite easily approachable, thanks to the broad DIY CNC and 3D printing communities. The plotter consists of a pair of stepper motors, driven by an off-the-shelf RAMPS 1.4 controller and an Arduino Mega 2560. The motors are mounted at the top corners of the blackboard, and move the pen holder via a pair of toothed belts, counter-weighted for stability. The pen holder itself mounts a simple permanent marker, and uses a servo to push the holder away from the paper for retraction, rather than moving the pen itself. Control of the system is via the Makelangelo firmware, an open-source effort capable of driving a wide variety of CNC motion systems.

The final result is a simple plotter using readily available parts that can reliably plot large graphics on a piece of A1 paper. We’re particularly impressed by the clean, continuous lines it produces – testament to a sound mechanical design.

We see plenty of plotters around these parts; even rotary types that can draw on curves. Video after the break.

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Listening To Long Forgotten Voices: An Optical Audio Decoder For 16 Mm Film

January 2, 2021 by 21 Comments

Like many of us, [Emily] found herself on COVID-19 lockdown over the summer. To make the most of her time in isolation, she put together an optical audio decoder for old 16 mm film, built using modern components and a bit of 3D printing.

It all started with a broken 16 mm projector that [Emily] got from a friend. After repairing and testing the projector with a roll of film bought at a flea market, she discovered that the film contained an audio track that her projector couldn’t play. The audio track is encoded as a translucent strip with varying width, and when a mask with a narrow slit is placed over the top it modulates the amount of light that can pass through to a light sensor connected to speakers via an amplifier.

[Emily] used a pair of razor blades mounted to a 3D printed bracket to create the mask, and a TI OPT101 light sensor together with a light source to decode the optical signal. She tried to use a photoresistor and a discrete photodiode, but neither had the required sensitivity. She built a frame with adjustable positions for an idler pulley and the optical reader unit, an electronics box on one end for the electronic components, and another pulley attached to a stepper motor to cycle a short loop of the film.

Most of the projects we see involving film these days are for creating digital copies. You can digitize your old 35 mm photo film using a Raspberry Pi, some Lego pieces, and a DSLR camera, or do the same for 8 mm film with a 3D printed rig. Continue reading “Listening To Long Forgotten Voices: An Optical Audio Decoder For 16 Mm Film” →

Checking In On Low-Cost CNC Machines

January 2, 2021 by 43 Comments

Low cost 3D printers have come a long way in the last few years, but have entry-level CNC machines improved by the same leaps and bounds? That’s what [ModBot] recently set out to find. Despite getting burned pretty badly on a cheap CNC a few years back, he decided to try again with a sub $400 machine from FoxAlien. You can see his full review after the break.

The machine looks very similar to other generic CNC machines you see under many brand names, sometimes for a good bit less. The 3018 number is a giveaway that the work area is 30×18 cm and a quick search pulled up several similar machines for just a bit more than $200. The FoxAlien did have a few nice features, though. It has a good-looking build guide and an acrylic box to keep down the shaving debris in your shop. There are also some other nice touches like a Z-axis probe and end stops. If you add those items to the cut-rate 3018 machines, the FoxAlien machine is pretty price competitive when you buy it from the vendor’s website. The Amazon page in the video shows $350 which is a bit more expensive but does include shipping.

As with most of these cheap CNC machines, one could argue that it’s more of an engraver than a full mill. But on the plus side, you can mount other tools and spindles to get different results. You can even turn one of these into a diode laser cutter, but you might be better off with something purpose-built unless you think you’ll want to switch back and forth often.

This reminded us of a CNC we’ve used a lot, the LinkSprite. It does fine for about the same price but we are jealous of the enclosure. Of course, half the fun of owning something like this is hacking it and there are plenty of upgrades for these cheap machines.