A gray 3d-printed box with RV-bridge embossed on it, and a connector-terminated bundle of wires coming out of it.

RV-Bridge Takes HomeKit To The Open Road

March 9, 2023 by Arya Voronova 19 Comments

In the world of proprietary protocol darkness, it’s comforting to see that the RV realm (Recreational Vehicle, also known as a motorhome) has mostly settled on RV-C, an open protocol that lets various devices and systems inside an RV talk to each other over CAN. The undeniable openness of RV-C is surprising, but we haven’t seen many hobbyists tinker with it — yet.

Now, [Randy Ubillos] sets an example — his gift to us is an ESP32 firmware called RV-Bridge and it lets you control your RV’s RV-C network from HomeKit. After all, your motorhome could benefit from home automation, too!

The RV-C network in [Randy]’s family RV already had a factory-provided front-end and an iOS app, but naturally, it had a limited set of features. Having looked around online he found that both RV-C and HomeKit had open libraries for them, and set out to join these worlds together.

Now he’s released the first revision of RV-Bridge, fully-featured enough for comfortable day-to-day use, and with a setup guide for those who want to try it out! When it comes to hardware, you’ll want an ESP32 board with CAN support — [Randy] has found a perfect board for sale, and made it even more fitting by designing a 3D printed case for RV use; as usual, files are on GitHub!

Making your stock RV more comfy through hacker methods is exactly what we expect to grace our tips line! The kinds of RV projects we’ve seen so far, are also outstandingly cool, yet of different kind – things like building your own RVs out of something not meant to be an RV, whether it’s an abandoned airliner, a school bus, or a jet engine! Oh, and if your hackerspace owns a RV, you can always convert it to something else, be it a mobile hackerspace or a spaceship simulator.

A man riding a motorized wooden sled up a snowy hill

Never Walk Uphill Again With This Motorized Sled

March 2, 2023 by Robin Kearey 11 Comments

If you grew up in a snowy climate, chances are you’ve ridden a sled or toboggan when you were young. The downhill part of sledding is great fun, but dragging the thing back up gets boring quickly. [Luis Marx] had been dreaming of sledding uphill since he was a child, and decided to make his dream come true by building himself a motorized sled (video, in German, embedded below).

The sled is powered by two DC electric motors driving a continuous track, like a rudimentary snowmobile. The motors were originally designed for electric bikes, and can develop 30 newton-meters of torque each. [Luis] designed and 3D-printed a custom set of drive wheels to link the track to the bike motors. Two motor controllers enable basic speed control, while a beefy battery carries enough juice for multiple trips up and down a slope.

The motorized track is mounted on a clever frame that can swing up or down and is held in place by two spring-loaded pins. This way, you can simply lift the system off the snow when you’re ready to slide downhil, and swing it down again when you want the sled to do the pulling.

With winter nearing its end, the snow near [Luis]’s home in southern Germany was too soft to get much traction, but subsequent tests in a ski resort up in the Alps showed the system working perfectly. It even had enough traction to pull a second sled behind it. Perhaps some proper suspension could make it go faster on the downhill run, too.

Continue reading “Never Walk Uphill Again With This Motorized Sled” →

A line art schematic of a bicycle CVT drive. Two large green circles at the bottom have the text "1. Increases speed" where the crank arm would enter the system. A series of cam arms highlighted in red say "2. Converts from rotary to reciprocating motion." Finally, a blue highlighted bearing says "3. Converts from reciprocating back to rotary motion."

A Look Inside Bicycle Gearboxes

March 2, 2023 by Navarre Bartz 23 Comments

While bicycle gearboxes date back to at least the 1920s, they’re relatively unseen in bike racing. One exception is Honda’s race-winning mid-drive gearboxes, and [Alee Denham] gives us a look at what makes these unique drives tick.

Honda has developed three generations of bicycle gearbox as part of their company’s R&D efforts, but none have ever been released as a commercial product. Designed as a way for their engineers to stretch their mental muscles, the gearboxes were only used in bike races and seen at a few trade shows. In 2004, the third gen “derailleur in a box” led to the first gearbox victory in the Downhill World Cup Circuit.

The third gen gearbox differs significantly from the CVT drivetrains in the first and second generation gearboxes, but it is unclear why Honda abandoned the CVT. [Denham] has a nice animation detailing the inner workings of these CVTs based on information from the original patents for these rarely seen gearboxes.

Derailleurs remain the primary drivetrain in racing due to their lighter weight and higher overall efficiency. While still expensive, the decreased maintenance of gearbox drivetrains make a lot of sense for more mundane cycling tasks like commuting or hauling cargo, but only time will tell if the derailleur can be supplanted on the track and trail.

For more on bicycle drivetrains, check out this chainless digital drivetrain or the pros and cons of e-bike conversions.

Continue reading “A Look Inside Bicycle Gearboxes” →

A grey car sits in the background out of focus, its front facing the camera. It sits over an asphalt roadway with a metal rail extending from the foreground to behind the car in the distance. The rail has a two parallel slots and screws surrounding the slots running down the rail.

What Happened To Sweden’s Slot Car EV Road?

March 1, 2023 by Navarre Bartz 60 Comments

Many EVs can charge 80% of their battery in a matter of minutes, but for some applications range anxiety and charge time are still a concern. One possible solution is an embedded electrical rail in the road like the [eRoadArlanda] that Sweden unveiled in 2016.

Overhead electrical wires like those used in trolleys have been around since the 1800s, and there have been some tests with inductive coils in the roadway, but the 2 km [eRoadArlanda] takes the concept of the slot car to the next level. The top of the rail is grounded while the live conductor is kept well underground beneath the two parallel slots. Power is only delivered when a vehicle passes over the rail with a retractable contactor, reducing danger for pedestrians, animals, and other vehicles.

One of the big advantages of this technology being in the road bed is that both passenger and commercial vehicles could use it unlike an overhead wire system that would require some seriously tall pantographs for your family car. Testing over several Swedish winters shows that the system can shed snow and ice as well as rain and other road debris.

Unfortunately, the project’s website has gone dark, and the project manager didn’t respond when we reached out for comment. If there are any readers in Sweden with an update, let us know in the comments!

We’ve covered both overhead wire and embedded inductive coil power systems here before if you’re interested in EV driving with (virtually) unlimited range.

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When One Cylinder Isn’t Enough: The Briggs And Stratton V8

February 28, 2023 by Jenny List 13 Comments

The Briggs & Stratton single cylinder sidevalve engine is one that has been in production in one form or another for over a century, and which remains one of the simplest, most reliable, and easiest to maintain internal combustion engines there is. The little single-cylinder can be found on lawnmowers and other similar machinery everywhere, so it’s rather easy to find yourself in possession of more than one. [Lyckebo Mekaniska] evidently had no shortage of them, because he’s produced a V8 engine for a small lawn tractor using eight of them. A small air-cooled V8 sidevalve is something of a unique engine to be made in the 2020s, and the series of videos is definitely worth a watch from start to finish. We’ve been keeping an eye on this build for a while now, and we’ve embedded it below the break for your entertainment.

A CAD view of the V8 engine — Clearly a lot of CAD work has gone into this build.

For an engine which uses mass-produced engines for its construction, this one still relies heavily on parts machined from first principles. The cylinder blocks, valves, pistons, and crank rods are Briggs & Stratton, the rest is made in the workshop. It’s a design with the valves on the outside — so instead of the single camshaft you might expect from experience with OHV engines nestling in the V above the camshaft it has two camshafts at the bottom of the crankcase.

The crankcase is cast in sections first, followed by the machining of the crankshaft and camshafts, then the preparation of the cylinders.. The engine is assembled with a home made alternator on its flywheel and a conventional distributor from a donor vehicle. The lubrication system is another work of the machinist’s art, and the simple straight-through exhaust system is more at home on a drag racer than a lawnmower. Finally we see it running, and it sounds the business. Most recently he’s had to deal with a seizure and a replacement cylinder, but now it’s back together and he’s working on an improved cooling system.

All in all this is one heck of a build, and we wish we had some of those skills. We’re not sure whether he’ll mow the lawn with this thing, but one thing’s for sure, lawnmower hacking has quite a past.

Continue reading “When One Cylinder Isn’t Enough: The Briggs And Stratton V8” →

Cart Cruises Abandoned California Rail

February 25, 2023 by Bryan Cockfield 20 Comments

Southern California is known for its nearly perfect year-round climate, excellent surf, and extremely high cost of living, but once you get away from the coast things are radically different. Rural California has huge tracts of land run by the Bureau of Land Management (BLM), which is publicly accessible to anyone willing to venture into the deserts. There’s not much in the way of infrastructure out there, but [Ryan] does have a unique way of traveling through it using abandoned railroad lines and this custom rail cart.

The frame of this cart is simple enough, it’s little more than 2×3 framing with a plywood deck. Some extra support is added for the motor mount and for the seating location. It uses slightly longer go-kart axles to accommodate the width of the railroad, and a small six horsepower gas engine with a single gear to power the rear axle. There are no brakes other than the riders’ shoes, and while this all seems straightforward enough the real hack here is [Ryan]’s custom wheels. He found that steel or cast wheels were not particularly comfortable on long journeys so after a few attempts he has come up with a home-built polyurethane wheel which is cast in a mold around a steel go-cart wheel and then trimmed on a lathe.

For pure exploration, there’s almost no better place to go than the American west thanks to all the public BLM land available. In this cart, you can explore long distances using an extremely low-cost method of transportation. We’ve added another video of [Ryan] exploring this area below the break to show the cart being used, too, but if you’d like a more multipurpose vehicle to use on abandoned rail near you, take a look at this bicycle which is converted to operate on the railroad.

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Bridging The Gap Between Dissimilar Road Types With Foam

February 10, 2023 by Ryan Flowers 27 Comments

When you think of driving up or down an embankment, do you ever wonder how much foam you’re currently driving on? Probably not, because it hardly seems like a suitable building material. But as explained by [Practical Engineering] in the video below the break, using an expanded material to backfill an embankment isn’t as dense as it sounds.

In many different disciplines, mating dissimilar materials can be difficult: Stretchy to Firm; Soft to Hard; Light to Heavy. It’s that last one, Light to Heavy, that is a difficult match for roadways. A bridge may be set down in bedrock, but the embankments approaching it won’t be. The result? Over time, embankment settles lower than the bridge does, causing distress for cars and motorists alike. What’s the solution?

To mitigate this, engineers have started to employ less dirty materials to build their otherwise soil based embankments. Lightweight concrete is one solution, but another is Expanded Polystyrene (EPS) foam. Its light weight makes installation simple in anything but a strong breeze, and it’s inexpensive and durable. When used properly, it can last many years and provide a stable embankment that won’t settle as far or as quickly as one made of dirt. Because as it turns out, dirt is heavy. Who knew?

Aside from roadways and bespoke aircraft, EPS foam has also been used for making home insulation. What’s your favorite use for EPS foam? Let us know in the comments below.

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