Restoring A Forgotten Dot-Matrix Printer

January 26, 2019 by Jenny List 15 Comments

Dot matrix printers are the dinosaurs that won’t go extinct. They are not unlike a typewriter with the type bars behind the ink ribbon replaced by a row of metal pins controlled by solenoids, each pin being capable of printing a single pixel. At their best they could deliver a surprising level of quality, but their sound once heard is not forgotten, because it was extremely LOUD.

[Wpqrek] bought an old dot-matrix printer, a Commodore MPS 803. Sadly it didn’t live up to the dot-matrix reputation for reliability in that it didn’t work, some of its pins weren’t moving, so he set to on its repair. Behind each of those pins was a solenoid, and after finding a crack in the flexible ribbon to the head he discovered that some of the solenoids were open-circuit. On dismantling the head it became apparent that the wires had detached themselves from the solenoids, so he very carefully reattached new wires and reassembled the unit. Of course, he had no replacement for the flexible ribbon, so he made a replacement with a bundle of long lengths of flexible hook-up wire. This hangs out of the top of the printer as it follows the carriage, but for now it keeps the device working.

Dot-matrix printers are a favourite for our readership. Among others, we’ve seen another Commodore get the Python treatment, as well as an Apple capable of printing in full colour.

Silent Stepper Drive Makes A Nicer Watch Winder

January 24, 2019 by Lewin Day 12 Comments

Mechanical watches are great in that they never need batteries, but they are simultaneously less than great in that they will lose time if not worn or otherwise regularly agitated. The ridiculous solution to this is the watch winder, which automatically rotates your mechanical watches for you, while you’re not wearing them. This is probably the item you’ll miss the least once the apocalypse hits. [Kristopher] wanted a nice quiet watch winder for his bedside table, but existing solutions were either too loud or too expensive. As is often the case, hacking ensued.

[Kristopher] had decided that starting from scratch was too much hassle. The cheaper watch winders on the market had acceptable quality enclosures, but were simply too loud. [Kristopher] sourced a $40 unit from Amazon, and proceeded to gut the drivetrain. This was replaced with a Sparkfun stepper motor and a Trinamic SilentStepStick – an advanced stepper motor driver that uses several techniques to reduce noise during operation.

An Arduino Nano was substituted as the brains of the operation, communicating with the stepper driver and allowing the winder to be configured for different wind rates. [Kristopher] reports that the device operates near-silently, and the total cost came in well below that of a high-end luxury winder.

Mechanical watches don’t always get a lot of attention these days, but we’ve seen one built from the ground up before. As always, with tips – send ’em if you got ’em.

Open Sourced Carbon Fiber Rod Ends

January 22, 2019 by Lewin Day 18 Comments

Modellers and makers who have been around the block for a few decades generally have their preferred materials. Balsa wood, sheet metal, brass tube… these were all staples of the hobbyist workshop. Composites are very much the new kid on the block and are starting to gain more of a foothold in the hobby marketplace. [Anthony] has been experimenting in this area, and has created some useful attachments for carbon fiber tubing.

The fittings are designed to be lasercut from aluminium or 3D printed. The rod ends are a simple two-piece design that slots together, before insertion into the carbon fiber rod. [Anthony] shows off a series of rods being used as linkages with a stepper motor, before performing pull-out tests on the links. Installed with cyanoacrylate glue, the link holds up to a pull load in excess of 180 lbs. The strength is impressive, and [Anthony] also talks about how to install the appropriate bearings to use the links for motion projects.

Overall, these links will likely prove useful to anyone using carbon fiber rods in a build, and helpfully, the required files are all available on GitHub. The source material is now cheap and readily available online, and is strong and resilient when used properly. We’ve seen carbon fiber popping up in a lot more projects recently, too. Video after the break.

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To Make Reproduction Train Whistles, The Old Ways Are Best

January 21, 2019 by Donald Papp 9 Comments

Late last year, artist [Steve Messam]’s project “Whistle” involved 16 steam engine whistles around Newcastle that would fire at different parts of the day over three months. The goal of the project was bring back the distinctive sound of the train whistles which used to be fixture of daily life, and to do so as authentically as possible. [Steve] has shared details on the construction and testing of the whistles, which as it turns out was a far more complex task than one might expect. The installation made use of modern technology like Raspberry Pi and cellular data networks, but when it came to manufacturing the whistles themselves the tried and true ways were best: casting in brass before machining on a lathe to finish.

The original whistles are a peek into a different era. The bell type whistle has three major components: a large bell at the top, a cup at the base, and a central column through which steam is piped. These whistles were usually made by apprentices, as they required a range of engineering and manufacturing skills to produce correctly, but were not themselves a critical mechanical component.

In the original whistle shown here, pressurized steam comes out from within the bottom cup and exits through the thin gap (barely visible in the image, it’s very narrow) between the cup and the flat shelf-like section of the central column. That ring-shaped column of air is split by the lip of the bell above it, and the sound is created. When it comes to getting the right performance, everything matters. The pressure of the air, the size of the gap, the sharpness of the bell’s lip, the spacing between the bell and the cup, and the shape of the bell itself all play a role. As a result, while the basic design and operation of the whistles were well-understood, there was a lot of work to be done to reproduce whistles that not only operated reliably in all types of weather using compressed air instead of steam, but did so while still producing an authentic re-creation of the original sound. As [Steve] points out, “with any project that’s not been done before, you really can’t do too much testing.”

Embedded below is one such test. It’s slow-motion footage of what happens when the whistle fires after filling with rainwater. You may want to turn your speakers down for this one: locomotive whistles really were not known for their lack of volume.

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Front Door Camera Sends Automatic Alerts By Text

January 21, 2019 by Lewin Day 25 Comments

In these turbulent times, journalists fearmonger and honest citizens fear for the safety of their homes and themselves. Adding some security features can allay these fears, and with the advent of cheap technology, front door cameras have become popular. There’s a wide array of options on the market, but short of watching hours of logged video, they’re not always super useful. Adding some smarts can really help – as [Peter Quinn] has done.

For this project, [Peter] decided on a JeVois smart camera. More than just a USB webcam, it also packs a quad-core processor running machine vision algorithms. This allows object recognition and other tasks to be run on the camera itself. In this setup, [Peter] configured the JeVois camera to detect people. When a human is detected upon the doorstep, the camera sends a message to the connected Raspberry Pi over serial. The Raspberry Pi then captures a JPEG still from the camera over the USB connection, and, using Twilio, sends a notification to [Peter]’s phone.

It’s a well-integrated system that automatically photographs visitors to [Peter]’s home, requiring little to no interaction from the user. We’ve seen other integrated machine vision platforms, too – such as the OpenMV, which got its start as a Hackaday Prize entry, way back in 2017.

This Monowheel Is Bright Orange, And We Want One

January 16, 2019 by Lewin Day 24 Comments

Monowheels are a singular form of transport. Like electric scooters and the Segway, they are remarkably impractical for getting from point A to point B, are expensive to build or buy, and make you look faintly silly as you ride them down the street. However, we’d be hard pressed to find a member of the Hackaday team that wouldn’t at least want a go on one for half an hour. [MakeItExtreme] felt the same way, and built one of their own.

The build starts with a tube bender, used to form 40mm tubing into a continuous circle to form the main wheel. Teflon is then turned to produce several rollers that interface the main wheel to the inner frame. Several small motorbike tyres were cut apart to create the tread to provide some decent grip. Power comes courtesy of a 110cc four stroke engine, allowing this thing to go just fast enough to get the rider seriously injured in the event of an accident. The team reports stability is poor at low speed, but remarkably good once above 30 km/h.

The team did a great job, and we particularly enjoy the bright orange paint scheme and fetching decals that really finish it off well. The monowheel concept is remarkably similar to the diwheel, which we’ve seen applied to old Fords with somewhat terrifying results. Video after the break.

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New Contest: 3D Printed Gears, Pulleys, And Cams

January 16, 2019 by Mike Szczys 40 Comments

One of the killer apps of 3D printers is the ability to make custom gears, transmissions, and mechanisms. But there’s a learning curve. If you haven’t 3D printed your own gearbox or automaton, here’s a great reason to take the plunge. This morning Hackaday launched the 3D Printed Gears, Pulleys, and Cams contest, a challenge to make stuff move using 3D-printed mechanisms.

Adding movement to a project brings it to life. Often times we see projects where moving parts are connected directly to a servo or other motor, but you can do a lot more interesting things by adding some mechanical advantage between the source of the work, and the moving parts. We don’t care if it’s motorized or hand cranked, water powered or driven by the wind, we just want to see what neat things you can accomplish by 3D printing some gears, pulleys, or cams!

No mechanism is too small — if you have never printed gears before and manage to get just two meshing with each other, we want to see it! (And of course no gear is literally too small either — who can print the smallest gearbox as their entry?) Automatons, toys, drive trains, string plotters, useless machines, clockworks, and baubles are all fair game. We want to be inspired by the story of how you design your entry, and what it took to get from filament to functional prototype.

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