Mix And Match Parts To Build A Better Mountain Bike Derailleur

August 13, 2019 by 4 Comments

Mountain bikers take their sport seriously, and put their bikes through all manner of punishment in the course of a ride. This has given rise to a wide range of specialist equipment, such as suspension, disc brakes and even clutch derailleurs, which help reduce chain slap when riding over rough terrain. However, these specialist derailleurs aren’t available for all applications, so sometimes you’ve gotta hack together your own.

Shimano clutch derailleurs are only really available for 10-speed rear cassettes and up, due to a change in derailleur ratio compared to the earlier 6 to 9 speed cassettes. Using a derailleur designed for 10-speed operation on a rear cassette with fewer gears won’t shift properly.

[SzurkeEg] was inspired by earlier work, and realised that by combining parts from several generations of Shimano hardware, it was possible to build a working clutch derailleur for 6 to 9 speed rear cassettes. The main parallelogram is what handles the positioning of the derailleur, and is sourced from a 9-speed part to get the gear indexes correct.The rest of the parts are sourced from later models with the clutch feature built in.

It’s a smart mechanical hack, and one that isn’t necessarily the most intuitive. But by having a go, and seeing what’s possible, now a whole generation of mountain bikes can tear up the trail like never before. We’ve seen Shimano gear hacked before, too. Video below the break. Continue reading “Mix And Match Parts To Build A Better Mountain Bike Derailleur” →

Bolt-On Stepper Motor Driver For The Raspberry Pi

August 13, 2019 by 9 Comments

For his entry into the 2019 Hackaday Prize, [Tobius Daichi] is working on adding some motion control capabilities to everyone’s favorite Linux SBC. His 3+Pi board attaches to the Raspberry Pi’s GPIO header and gives you a convenient way to control four individual stepper motors. Perfect for a 3D printer, laser cutter, CNC, or anything else you can think of that needs to move in a few dimensions.

But such a simplistic description of the 3+Pi might be underselling it a bit. While [Tobius] says he was inspired by the classic Arduino CNC Shield that powers countless DIY 3D printers, he’s managed to improve on the concept. Rather than having the host Pi communicate directly with the stepper drivers, the 3+Pi features an onboard STM32F302CBT6 that handles the actual motor control. The Pi just needs to tell it what to do over UART.

If you’re looking to do things in real-time, having an onboard microcontroller handle the low-level aspects of talking to the stepper drivers can be a big help. A natural extension for this board could be support for the Klipper firmware, which leverages the fact that the Raspberry Pi is many times more powerful than your average 3D printer control board. With the Pi handling the math and providing the microcontroller instructions, Klipper allows for faster and more accurate printing than the microcontroller alone could accomplish.

As for the stepper drivers themselves, [Tobius] has decided to go with the Trinamic TMC2041-LA-T. This chip is notable as it puts dual drivers in one 48-QFN package, which is great if you’re looking to save space on your board. Some might complain that the 3+Pi doesn’t allow for easily swapping out the stepper drivers if you manage to cook one like on the Arduino CNC shield, but realistically you could say the same about many purpose-built stepper control boards.

[Tobius] is tackling this project by himself currently, but does mention that he’s open to teaming up with anyone who’s got an interest in this sort of thing. There have been previous attempts at creating Linux-powered 3D printer controllers in the past, but we think this approach holds particular promise if for no other reason than the Raspberry Pi’s popularity.

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Retrotechtacular: Predictions That Just Missed It

August 13, 2019 by 40 Comments

Few occupations are more fraught with peril than predicting the future. If you are a science fiction author, it might not matter, but if you are trying to design the next game-changing piece of hardware, the stakes are higher.

It seems like, for the most part, even if you manage to get some of the ideas right, the form is often way off. Case in point: telemedicine. Today you can visit a doctor using video conferencing with your phone or a PC for many common maladies. A new idea? Not really. Hugo Gernsback wrote about it in Radio Electronics back in 1955.

Gernsback wrote:

The average medical doctor today is overworked and short-lived. There are never enough doctors anywhere for the world’s constantly multiplying population. Many patients die because the doctor cannot reach them in time, particularly at night and in remote regions.

…[H]e can only see a few [patients] during the day. With increasing traffic congestion, many doctors refuse to make personal calls — execept in emergencies. Even then they arrive often too late. Much of this dilemma will be archaic in the near future, thanks to the Teledoctor.

Gernsback envisioned a doctor using what we now call Waldos similar to what people use to manipulate radioactive material. These super mechanical hands (Gernsback’s words) would allow the doctor to write a prescription, pour liquids, or even diaper a baby thanks to a sense of touch built into them.

Oddly enough, Gernsback’s vision included renting a teledoctor from the drugstore for $3.50 a day. This way, the doctor could call on you and then follow up as well. The drug store would deliver the machine and it would — get this — connect to your phone:

A cord with the a telephone plug attached to the teledoctor instrument is now plugged into a special jack on your telephone. Future telephones will be provided with this facility. The TV signals and telehand electronic signals, etc., will all travel over the closed circuit telephone lines.

In a footnote, Gernsback notes that you can’t send a 525-line TV signal on current phone lines, but a 250-350 line picture was possible and that would be sufficient.

Visionary? In some ways, maybe. The basic idea is coming true today, although it isn’t likely doctors will do surgery or inject you remotely in your home anytime soon. The special telephone plug sort of came true and is already obsolete. The images, by the way, are the ones that accompanied the original article in Radio Electronics.

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Electric Dump Truck Tricycle Is No Toy

August 13, 2019 by 31 Comments

There are some utility bicycles on the market, some with electric motors to help carry a good bit of cargo. If you really need to haul more weight than a typical grocery-getter like this, you’ll want to look into a tricycle for higher capacity loads. Nothing you’ll find will match this monstrous electric tricycle hand-built by [AtomicZombie] out of junkyard parts, though. It’s a mule.

Since [AtomicZombie] sourced most of the underpinnings of this build from the junkyard, it’s based on an old motorcycle frame combined with the differential from a pickup truck, with a self-welded frame. He’s using an electric motor and a fleet of lead acid batteries for the build (since weight is no concern) and is using a gear reduction large enough to allow him to haul logs and dirt with ease (and dump them with the built in dump-truck bed), and even pull tree stumps from the ground, all without taxing the motor.

[AtomicZombie] documented every step of the build along the way, and it’s worth checking out. He uses it as a farm tractor on his homestead, and it is even equipped with a tow hitch to move various pieces of equipment around. Unlike a similar three-wheeled electric contraption from a while back, though, this one almost certainly isn’t street legal, but it’s still a blast!

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Automate The Freight: Platooning

August 13, 2019 by 34 Comments

On yet another one of those long, pointless road trips that seemed to punctuate my life starting when I got my license, I was plying the roads somewhere in eastern Pennsylvania with a friend. He told me that on long trips he’d often relieve the boredom by finding another car from the same state as his destination, and then just follow it. I wasn’t sure then how staring at the same car, hour after hour, mile after mile, would do anything but increase the boredom while making you look sort of creepy, but it seemed to work for him.

What works for college kids in cars also works for long-haul truckers, and the concept of a convoy has long been a fact of life on the road and a part of popular culture. Hardly a trip on the US Interstate goes by without seeing a least two truckers traveling in close formation, partly for companionship and mutual support but also for economic reasons. And now technology is poised to take convoying to the next level, as platooning becomes yet another way to automate the freight.

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Spin Me Right Round, Baby: Generator Building Experiments For Mere Mortals

August 13, 2019 by 38 Comments

How many of you plan to build a wind-powered generator in the next year? Okay, both of you can put your hands down. Even if you don’t want to wind your coils manually, learning about the principles in an electric generator might spark your interest. There is a lot of math to engineering a commercial model, but if we approach a simple version by looking at the components one at a time, it’s much easier to understand.

For this adventure, [K&J Magnetics] start by dissect a commercial generator. They picked a simple version that might serve a campsite well, so there is no transmission or blade angle apparatus to complicate things. It’s the parts you’d expect, a rotor and a stator, one with permanent magnets and the other with coils of wire.

The fun of this project is copying the components found in the commercial hardware and varying the windings and coil count to see how it affects performance. If you have ever wound magnet wire around a nail to make an electromagnet, you know it is tedious work so check out their 3D printed coil holder with an embedded magnet to trigger a winding count and a socket to fit on a sewing machine bobbin winder. If you are going to make a bunch of coils, this is going to save headaches and wrist tendons.

They use an iterative process to demonstrate the effect of multiple coils on a generator. The first test run uses just three coils but doesn’t generate much power at all, even when spun by an electric drill. Six windings do better, but a dozen finally does the trick, even when turning the generator by hand. We don’t know about their use of cheap silicone diodes though, that seems like unintentional hobbling, but we digress.

Making turbine blades doesn’t have to be a sore chore either, and PVC may be the ticket there, you may also consider the vertical axis wind turbine which is safer at patio level. Now, you folks building generators, remember to tip us off!

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Shop-Made Tools Turn Cheap Steel Into Telescoping Tubes

August 13, 2019 by 24 Comments

Beginning metalworkers are often surprised at just how cheap steel can be. It’s a commodity made by the gigaton, and there are always plenty of extra pieces and scraps left over from big projects that are available for pennies a pound. But what you’ve got is often not what you need, especially when it’s steel tubing with welded seams that prevents one tube from fitting inside another.

[Jason Marburger] from Fireball Tool has some great tips for cleaning interior welds in steel tubing. The first part of the video below details manual methods for cleaning off seam welds, including chiseling, sanding with a narrow belt sander, and grinding them down with a die grinder. Those all work well, but only for short lengths of tubing. Longer tubes need special treatment, which is where the clever tools [Jason] designed come in handy.

By attaching a chunk of high-speed steel to a slug made from the next size tube down and driving it through the tube to be cleaned with a hefty piece of threaded rod, he basically created ain internal shaper to shave the weld down. It works like a charm, as does the tool he made for round tubing by laying a bead of hard facing welding rod around the edge of a mild steel slug. Driving this tool into the seamed round tubing with a shop press cleaned up the weld nicely too.

Hats off to [Jason] for coming up with a couple of great shop tips to keep in mind. We’ve seen similar expedient tools for metalworking lately, like this homemade die-punching tool and a linear track to keep your plasma cutter in line.

Continue reading “Shop-Made Tools Turn Cheap Steel Into Telescoping Tubes” →