Building A Continuously Variable Transmission With Lego

February 5, 2021 by Lewin Day 13 Comments

The first continuously variable transmission fitted to an automobile actually has its roots in the late 19th century, though the technology has only become popular in the last two decades or so. While a relatively complex technology in its modern automotive form, it’s still possible to illustrate the basic principles with everyone’s favourite mechanical learning toy – Lego.

The transmission as built isn’t great at high torque delivery, as the belt tends to slip on the smooth plastic of the cones. Increasing friction would help.

The build consists of a Lego motor driving the transmission’s input shaft, upon which a cone is mounted. A similar cone is mounted on the output shaft, and a rubber belt stretched between the two. With the cones mounted in opposing directions, the gear ratio can be continually varied by changing where upon the cones the belt rides. By riding on the small diameter section of the input cone, the belt correspondingly rides on the large diameter section of the output cone, leading to a slower, high torque output. By sliding the belt to the other end of the cone, the ratios are reversed, leading to high output speed with less torque.

The demonstration works somewhat differently than modern automotive models, but the basic concept is the same. It’s also limited in its torque transfer ability by the coefficient of friction of the plastic Lego parts. Despite this, it’s a quick way to illustrate the mechanisms at play, and where some of the common losses are in such a system. If you prefer your gearboxes of a more classic sequential design, we’ve seen those too, of course. Video after the break.

Continue reading “Building A Continuously Variable Transmission With Lego” →

Reverse-Engineering An Elevator Control Panel Results In Clicky Goodness

February 4, 2021 by Dan Maloney 9 Comments

We have to admit that in the hardware hacking universe, there aren’t generally too many chances to hack elevators. Well, at least not opportunities that don’t also include the risk of incarceration. But fortune favors the bold, and when he found the remains of an elevator control panel in an abandoned Croatian resort hotel, [Davor Cihlar] undertook an extensive and instructive reverse-engineering of the panel.

The video below highlights his efforts, which were considerable given the age and state of the panel. This is a relay-only control panel, after all, with most of the relays missing and a rat’s nest of wires connecting the sockets. So [Davor] put his “RevIng” concept to work. This uses a custom PCB with a microcontroller on-board that plugs into each relay socket and probes the connections between it and every other socket. Very clever stuff, and it presented him with the data needed to develop a ladder-logic diagram of the board, with the help of some custom software.

With the original logic in hand, [Davor] set about building a simulator for the panel. It’s a lovely piece of work, with buttons and lights to mimic the control panel inside the elevator car, as well as the call stations that would have graced each lobby of the hotel. Interestingly, he found logic that prevented the elevator from being called to some floors from anywhere but inside the car. The reason remains a mystery, but we suppose that a hotel built by Penthouse publisher [Bob Guccione] would have plenty of secrets.

We love the supremely satisfying clickiness of this build, and the reverse engineering prowess on display, but we can’t find much practical use for something like this. Then again, DIY elevators are a thing.

Continue reading “Reverse-Engineering An Elevator Control Panel Results In Clicky Goodness” →

Mechanical Seven-Segment Display, Smaller And Better Than The Original

February 4, 2021 by Dan Maloney 19 Comments

One thing we love here at Hackaday is when we get to track the evolution of a project over time. Seeing a project grow over time is pretty typical — scope creep is real, after all. But watching a project shrink can be a real treat too, as early versions get refined into sleeker and more elegant solutions.

This slimmed-down mechanical seven-segment display is a perfect example of that downsizing trend. When we saw [IndoorGeek]’s first vision of an electromechanical display, it was pretty chunky. Then as now, each segment is a 3D-printed piece with a magnet attached to the rear. The segments hover over solenoid coils, which when energized repel the magnet and protrude the segment, forming the desired digit. The old version used large, hand-wound coils, though, making the display pretty bulky front to back.

Version 2 of the display takes a page from [Carl Bugeja]’s playbook and replaces the wound coils with PCB coils. We’ve seen [Carl]’s coils on both rigid substrates and flex PCBs; [IndoorGeek] used plain old FR4 here. The coils occupy four layers so they have enough oomph to extend and retract each segment, and the PCB includes space for H-bridge drivers for each segment. The PCB forms the rear cover for the display, which is also considerably slimmed down for this version. What’s the same, though, is how good this display looks, especially with strong side-lighting — the shadows cast by the extended segments are striking against the plain white face of the display.

Congratulations to [IndoorGeek] on a great-looking build and a useful improvement over the original.

Continue reading “Mechanical Seven-Segment Display, Smaller And Better Than The Original” →

Sewage Maceration Is As Gross As It Sounds

February 4, 2021 by Lewin Day 100 Comments

Day to day, few of us really contemplate what’s happening on a deep, mechanical level when we use the toilet. The business is done, the toilet is flushed, and we go about our day. However, the magnificent technology of indoor sanitation should not be sniffed at, given the manner in which it facilitates a cleaner, more comfortable existence for us all.

The vast majority of flush toilets rely on the benefit of gravity to remove waste from the house. This necessitates that the toilet be installed above the sewage lines that exit the house. For most installations at ground floor and above, this isn’t a problem. However, on occasions you may encounter basements or houses with rooms at lower levels where a regular toilet simply won’t work. Obviously, a pump is in order, but human sewage being a mixture of liquids and solids makes this impractical. Instead, it must be turned into a slurry that can be pumped; a process known as sewage maceration. Buckle up!

Continue reading “Sewage Maceration Is As Gross As It Sounds” →

Building An Ultrasonic Levitation Rig

February 2, 2021 by Lewin Day 12 Comments

Levitation may sound like magic, but there are a wide variety of physical phenomena that can be manipulated to generate the desired effect. In this case, [Mirko Pavleski] has built a rig capable of levitating small, lightweight particles through the use of ultrasound.

The rig uses a 60W ultrasonic transducer, operating at approximately 40 KHz, to generate a standing wave in combination with a reflector – essentially a rigid piece of material off which sound waves can be bounced. The interaction between the sound waves as they are emitted from the transducer and bounce off the reflector creates what is known as a standing wave, wherein there are areas of high and low amplitude that do not move in space. These areas correspond to the wavelength of the emission from the transducer, and allow lightweight pieces of styrofoam to be placed in to the low amplitude areas, where they are held in place by the wave.

It’s quite astounding the first time you see it in action, as the tiny particles appear to simply float in the air apropos of nothing. We’ve explored deeper applications of the technique before, too. Video after the break.

Continue reading “Building An Ultrasonic Levitation Rig” →

Electronic Embroidery Birthday Card Is A Celebration Of Skills

February 1, 2021 by Kristina Panos 5 Comments

Hackers and makers can sometimes feel like they’re getting the short end of the stick when it comes to gift giving. You’re out there making thoughtful, intricate circuit sculptures, helpful software, or face masks for people, and what do you get in return? Okay, yes, usually gift cards or tools or other things that feed your creativity in the first place. But darn it, it would be nice to receive a handmade gift once in a while, right?

So here’s what you do: make friends with enough other makers that you find your birthday twin, or close enough that you both feel the warmth of the personal holiday you share. Then you get them to agree to trade handmade birthday presents with you. That’s more or less what happened between [Becky Stern] and [Estefannie], who seem to have found each other through the magic of sharing projects on YouTube.

[Becky]’s gift to [Estefannie] is a busy intersection of maker elements including graphic design, embroidery, electronics, and 3D printing. [Becky] started with the embroidery, which was made possible thanks to a new open-source library for Processing called PEmbroider. Once that was done, she 3D printed the frame and added the electronics — candle flicker LEDs for the birthday cake, and a handful of songs that are accessible via touch contacts screwed into the side of the frame. [Becky] added a real-time clock module so it plays a few extra songs on [Estefannie]’s actual birthday.

The most thoughtful element here is personalization, and it’s amazing what can happen when you put 100% of yourself into something that is 100% about someone else. Every bit of the art is personal to [Estefannie], and every atom of the build is pure [Becky]. Check out the demo and build video and see what [Estefannie] made for [Becky] after the break.

[Becky]’s varied creativity has graced these pages many times before. See how she bid adieu to 2020, built a daily affirmation mirror, and gave a mask-making masterclass in the early stages of the pandemic.

Continue reading “Electronic Embroidery Birthday Card Is A Celebration Of Skills” →

Proofing Press Proves DIY Is A-OK

January 29, 2021 by Kristina Panos 17 Comments

Back in the day when most people read the news on wood pulp, newspaper outfits would run off a test print on a small proofing press. This gave them a chance to check for typos before printing off thousands of newspapers on the real press.

These presses can be used for more than letterpress proofing, as [Paul] proves with this DIY version (YouTube, embedded below). They are simple machines that use a heavy roller on bearings to provide uniform pressure, so they’ll work for lino-cut printmaking and aquatint etchings, too.

The roller is the most important bit and is easily the most expensive part of a build like this one. [Paul]’s was fashioned by a UK machinist that he found through ebay. The total cost was £220 (~$300 USD), which is well below the thousand-pound mark where commercial machine prices start.

[Paul] made the base and handle out of plywood and CNC’d the side panels out of aluminium. These side panels contain bearings that hold the roller’s ends in place. As the roller moves back and forth, it slides along on another set of bearings the underside of the press. These bearings ride thin metal rails on the underside of the press so they don’t wear grooves into the wood over time.

[Paul]’s press looks fantastic and looks like it does a great job with everything he throws at it. Some uses require raising up the surface to be printed on to get a good transfer, so [Paul] might make it adjustable in the z-direction at some point in the future. Check out the build and walk-through video after the break.

If [Paul] looks familiar, it’s because we featured his equally impressive large-format book press last spring.

Continue reading “Proofing Press Proves DIY Is A-OK” →