Backyard Rope Tow From Spare Parts

March 20, 2025 by Bryan Cockfield 9 Comments

A few years ago, [Jeremy Makes Things] built a rope tow in his back yard so his son could ski after school. Since the lifts at the local hill closed shortly after schools let out, this was the only practical way for his son to get a few laps in during the week. It’s cobbled together from things that [Jeremy] had around the house, and since the original build it’s sat outside for a few years without much use. There’s been a lot more snow where he lives this year though, so it’s time for a rebuild.

The power source for the rope tow is an old gas-powered snowblower motor, with a set of rollers and pulleys for the rope made out of the back end of a razor scooter. Some polyurethane was poured around the old wheel hub so that the rope would have something to grip onto. The motor needed some sprucing up as well, from carburetor adjustment, fuel tank repairs, and some other pieces of maintenance before it could run again. With that out of the way it could be hoisted back up a tree at the top of the hill and connected to the long rope.

This isn’t the first time [Jeremy] has had to perform major maintenance on this machine either. Three years ago it needed plenty of work especially around the polyurethane wheel where [Jeremy] also had to machine a new wheel bearing in addition to all the other work that had to go into repairing it that time. From the looks of things though it’s a big hit with his son who zips right back up the hill after each ski run. Getting to the tops of ski runs with minimal effort has been a challenge of skiers and snowboarders alike for as long as the sport has been around, and we’ve seen all kinds of unique solutions to that problem over the years.

You’ve Got All Year To Print This Marble Machine Ornament For Your Christmas Tree

February 20, 2025 by Lewin Day 11 Comments

Most Christmas ornaments just hang there and look pretty. [Sean Hodgins] decided to whip up something altogether fancier and more mechanical. It’s a real working marble machine that hangs from the tree!

The build is simple enough, beginning with a translucent Christmas ornament shell readily available from most craft stores. Inside, a small motor spins a pinion, which turns a larger gear inside the body. As the larger gear spins, magnets embedded inside pick up steel balls from the base of the ornament and lift them up to the top. As they reach their zenith, they’re plucked off by a scoop, and then they roll down a spiral inside. As for power, [Sean] simply handled that with a couple of wires feeding the motor from a USB power bank. Just about any small battery pack would do fine.

The build is beautiful to watch and to listen to, with a gentle clacking as the balls circulate around. Files are on MakerWorld for the curious. We’ve featured some great Christmas decorations before, too. Video after the break.

Investigating Electromagnetic Magic In Obsolete Machines

February 5, 2025 by Bryan Cockfield 15 Comments

Before the digital age, when transistors were expensive, unreliable, and/or nonexistent, engineers had to use other tricks to do things that we take for granted nowadays. Motor positioning, for example, wasn’t as straightforward as using a rotary encoder and a microcontroller. There are a few other ways of doing this, though, and [Void Electronics] walks us through an older piece of technology called a synchro (or selsyn) which uses a motor with a special set of windings to keep track of its position and even output that position on a second motor without any digital processing or microcontrollers.

Synchros are electromagnetic devices similar to transformers, where a set of windings induces a voltage on another set, but they also have a movable rotor like an electric motor. When the rotor is energized, the output windings generate voltages corresponding to the rotor’s angle, which are then transmitted to another synchro. This second device, if mechanically free to move, will align its rotor to match the first. Both devices must be powered by the same AC source to maintain phase alignment, ensuring their magnetic fields remain synchronized and their rotors stay in step.

While largely obsolete now, there are a few places where these machines are still in use. One is in places where high reliability or ruggedness is needed, such as instrumentation for airplanes or control systems or for the electric grid and its associated control infrastructure. For more information on how they work, [Al Williams] wrote a detailed article about them a few years ago.

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A dismantled drill on a cluttered workbench

Going Brushless: Salvaging A Dead Drill

January 29, 2025 by Heidi Ulrich 26 Comments

Let’s face it—seeing a good tool go to waste is heartbreaking. So when his cordless drill’s motor gave up after some unfortunate exposure to the elements, [Chaz] wasn’t about to bin it. Instead, he embarked on a brave journey to breathe new life into the machine by swapping its dying brushed motor for a sleek brushless upgrade.

Things got real as [Chaz] dismantled the drill, comparing its guts to a salvaged portable bandsaw motor. What looked like an easy swap soon became a true hacker’s challenge: incompatible gear systems, dodgy windings, and warped laminations. Not discouraged by that, he dreamed up a hybrid solution: 3D-printing a custom adapter to make the brushless motor fit snugly into the existing housing.

The trickiest part was designing a speed control mechanism for the brushless motor—an impressively solved puzzle. After some serious elbow grease and ingenuity, the franken-drill emerged better than ever. We’ve seen some brushless hacks before, and this is worth adding to the list. A great tool hack and successful way to save an old beloved drill. Go ahead and check out the video below!

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Turning A Lada Into An EV With 50 Cordless Drills, Because Why Not?

January 1, 2025 by Donald Papp 47 Comments

[Garage 54] is no stranger to vehicle-related projects of the “because why not?” variety, and their latest is using 50 cordless drills combined into a monstrous mega-motor to turn a gutted (and extended) Lada into an electric vehicle (EV).

Doing this leans on some of [Garage 54]’s earlier projects, such as replacing the aforementioned Lada’s engine block with a frame containing sixteen chainsaws. That means they don’t need to start completely from scratch, and have a frame design that can drop into the vehicle once the “engine” is constructed.

Fifty cordless drills won’t set any efficiency records for EV engines, but it’s got a certain style.

Here’s what’s in the new engine: each of the drills has its chuck replaced with an aluminum pulley, and belts connect each group of drills to an output shaft. Ideally, every drill motor would run at the same time and at exactly the same speed, but one works with what they have. [Garage 54] originally worked to synchronize the drills by interfacing to each drill’s motor control board, but eventually opted to simply bypass all controls and power each drill’s motor directly from the batteries. Initial tests are done by touching bare cable ends with a turned-away face and squinted eyes, but we expect “Just A Big Switch” to end up in the final assembly.

It looks wild and we can think of more than a few inefficiencies present in a system like this, but the output shaft does turn and torque is being transferred, so the next step is interfacing to the car’s factory gearbox.

If it powers the car in any meaningful way, that Lada might very well become the world’s most gloriously hacked-together EV. And hey, if the power output of the EV motor is disappointing, you can just make your own.

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Behold A Geared, Continuously Variable Transmission

December 14, 2024 by Donald Papp 72 Comments

When it comes to transmissions, a geared continuously-variable transmission (CVT) is a bit of a holy grail. CVTs allow smooth on-the-fly adjustment of gear ratios to maintain a target speed or power requirement, but sacrifice transmission efficiency in the process. Geared transmissions are more efficient, but shift gear ratios only in discrete steps. A geared CVT would hit all the bases, but most CVTs are belt drives. What would a geared one even look like? No need to wonder, you can see one for yourself. Don’t miss the two videos embedded below the page break.

The outer ring is the input, the inner ring is the output, and the three little gears with dots take turns transferring power.

The design is called the RatioZero and it’s reminiscent of a planetary gearbox, but with some changes. Here’s how the most visible part works: the outer ring is the input and the inner ring is the output. The three small gears inside the inner ring work a bit like relay runners in that each one takes a turn transferring power before “handing off” to the next. The end result is a smooth, stepless adjustment of gear ratios with the best of both worlds. Toothed gears maximize transmission efficiency while the continuously-variable gear ratio allows maximizing engine efficiency.

There are plenty of animations of how the system works but we think the clearest demonstration comes from [driving 4 answers] with a video of a prototype, which is embedded below. It’s a great video, and the demo begins at 8:54 if you want to skip straight to that part.

One may think of motors and gearboxes are a solved problem since they have been around for so long, but the opportunities to improve are ongoing and numerous. Even EV motors have a lot of room for improvement, chief among them being breaking up with rare earth elements while maintaining performance and efficiency.

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Electric Bike Uses No Electronics, Weird Motor

December 9, 2024 by Lewin Day 24 Comments

E-bikes combine a bicycle with a big lithium battery, a speed controller, and a motor. What you get from that combination is simple, efficient transportation. [Tom Stanton] wanted to build an e-bike himself, but he did it without any of the fancy electronic components. But the real gem? The weird janky motor he built to run it.

The concept is simple. An e-bike is electric, in that it has an electric motor and a source of electric power. However, [Tom] intended to eliminate the electronic parts—the speed controller, any battery balancing hardware, and the like. Just think no transistors and microchips and you’ve got the right idea. Basically, [Tom] just built an e-bike with motor weak enough that it doesn’t need any fancy throttle control. He can just turn the motor hard on or off with a switch.

The bike is built around a reed switch motor. This uses magnets on a rotor, which interact with a reed switch to time pulses of electricity to coils which drive the motor. [Tom] wound the coils and built the motor from scratch using 3D printed components. The project quickly ran into problems as the reed switch began to suffer degradation from arcing, which [Tom] solved with some innovative tungsten contacts.

Controlling the bike is pretty simple—there’s just a switch connecting a capacitor bank to the motor to provide power on command. No electronics! However, [Tom] has also neatly set up the motor to charge a bank of supercapacitors when coasting downhill. In this regard, the bike can store power on a descent and then use it for a boost when required later on. Between the weird motor and the weedy capacitor bank, it doesn’t do much, but it does work.

If he’s looking for a more potent power source, perhaps the answer is already out on the street — in the form of a battery pack salvaged from the cells in discarded vapes.
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