Grinding A Bicycle Crank For Power Analysis

January 11, 2015 by Brian Benchoff 35 Comments

For [Mark] and [Brian]’s final project for [Bruce Land]’s ECE class at Cornell, they decided to replicate a commercial product. It’s a dashboard for a bicycle that displays distance, cadence, speed, and the power being generated by the cyclist. Computing distance, cadence and speed is pretty easy, but calculating power is another matter entirely.

The guys are using an ATMega1284 to drive an LCD, listen in on some Hall Effect sensors, and do a few calculations. That takes care of measuring everything except power. A quick search of relevant intellectual property gave then the idea of measuring torque at the pedal crank. For that, [Mark] and [Brian] are using a strain gauge on a pedal crank, carefully modified to be stiff enough to work, but flexible enough to measure.

A custom board was constructed for the pedal crank that measures a strain gauge and sends the measurements through a wireless connection to the rest of the bicycle dashboard. It works, and the measurements in the classroom show [Brian] is generating about 450 W when pedaling at 33 mph.

Video below.

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Boeing 777 From Manilla Folders, A 6+ Year Effort

January 3, 2015 by Matt Freund 67 Comments

The closer you look the more you will be in awe of this shockingly intricate 777 replica. The fully-articulating landing gear alone has over 2,000 parts and 200 hours of assembly, not even including the penny-sized tires with individually-cut lug nuts. All carved from manilla office folders by hand.

A high school ~~art~~ architecture class in 2008 inspired this build by teaching a few papercrafting techniques. When [Luca] got a hold of a precision Air India 777-300ER schematic, he started building this 5 foot long 1:60 scale model. His project has received a fair amount of media attention over the years, including some false reports that he was so focused on the build that he dropped out of college (he did, for 2 years, but for other reasons). 6.5 years in the making, [Luca] is rounding the homestretch.

The design is manually drawn in Illustrator from the schematics, then is printed directly onto the manilla folders. Wielding an X-acto knife like a watch-maker, [Luca] cuts all the segments out and places them with whispers of glue. Pistons. Axles. Clamps. Tie rods. Brackets. Even pneumatic hoses – fractions of a toothpick thin – are run to their proper locations. A mesh behind the engine was latticed manually from of hundreds of strands. If that was not enough, it all moves and works exactly as it does on the real thing.

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Offset Unicycle Built Mostly From A Single Bicycle

December 28, 2014 by Rick Osgood 32 Comments

[Lou’s] friends all said that it would be impossible to build a unicycle that had offset pedals. Moving the pedals to the front of the unicycle would throw off the balance and prevent the user from being able to ride it. [Lou] proved them wrong using mostly components from a single donor bicycle.

The donor bike gets chopped up into a much smaller version of itself. The pedals stay attached in the original location and end up being out in front of the rider. The seat is moved backwards, which is the key to this build. Having the rider’s legs out in front requires that there be a counter balance in back. Moving the seat backwards gets the job done with relative ease.

To prevent the hub from free wheeling, [Lou] lashes the sprocket directly to the wheel spokes using some baling wire. He also had to remove the derailer and shorted the chain. All of this gives the pedals a direct connection to the wheel, allowing for more control. The video does a great job explaining the build quickly and efficiently. It makes it look easy enough for anyone to try. Of course, actually riding the unicycle is a different matter. Continue reading “Offset Unicycle Built Mostly From A Single Bicycle” →

RGB Bike Rim Lights

December 26, 2014 by Marsh 8 Comments

[Yvo] sent us his latest creation, this awesome POV RGB bicycle rim light build, which features a circular interweaving of common RGB LEDs that face outward along the rim as they display constantly changing animations based on the wheel’s rpm.

Like many POV wheel builds, [Yvo]’s takes advantage of a hall effect sensor and stationary magnet to determine how fast the wheels are spinning. Unlike most POV builds, however, [Yvo’s] creation doesn’t have just one or two RGB sticks clamped onto a spoke. Instead, his wheels boast several individual RGB LED modules mounted along the rim.

Each wheel has six modules, and each module contains a scratch-build LED controller (a daisy chain of 74HC595 shift registers) that fits into a custom-made 3D-printed enclosure. The enclosures mounts onto some aluminum strips along with the RGB LEDs, and the aluminum strips mount to the wheels by straddling the rim.

At speed, the lights go into POV mode to simulate headlights / brakes with white in the front and red in the back. Check out the difference these custom circular modules make when riding and when at rest in a video below.

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DIY Bicycle Roller Helps Cure The Winter Blues

December 20, 2014 by Rich Bremer 46 Comments

Winter’s a-brewing and that is a downer for the everyday cycling enthusiast. There are certainly ‘bike trainers’ out on the market that will let you ride in your living room but they clamp to (or require replacing the) the rear axle. These bike trainers hold the bike in an upright position so that the rider can’t tip the bike and might feel a little boring for some. There is another indoor biking solution called a bicycle roller which is, just as it sounds, a few rollers on the ground that the bike wheels rest on and is not attached to the bike by any mechanical means. When the rider pedals the bike, the bike wheels spin the rollers. Even with the lack of forward momentum the spinning of the wheels is enough for the rider to stay upright.

[Sky-Monkey] wanted to bike during inclement weather and felt that a bike roller was simple enough for him to try building one. He likes building things and already had all the necessary parts kicking around his shop. The rollers are standard 3″ PVC pipe with plywood discs pressed into each end. The discs are counter-bored to accept standard skate bearings. Off the shelf steel rod make up the axles. The 3 rollers and axle assemblies are mounted in a wood frame made from dimensional lumber. It’s important that the front bike wheel also spins so [Sky-Monkey] made a power transmission belt out of cloth strap that spins the front roller with the rear.

The result is a fully functional bike roller that only cost a few hours of time to make. Video of this puppy in action after the break….

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Amateur Builds Super Deep Super Cheap Ocean Vehicle

December 19, 2014 by Matt Freund 41 Comments

During the summers [Doug] has been building a 75 foot sailing junk to be launched from America’s most inland port. When Oklahoma’s winter hits he heads indoors to work on an ROV that will prowl 3,000 feet below the surface. Originally building a piloted submarine, he grew bored and decided to use the sailboat as a carrier for his fleet of remote submersibles instead.

A consummate amateur, [Doug] is the first to admit how little he knows about anything and how much he enjoys the open source spirit: collaboration, cooperation and learning from others. Determination and hard work fills in everything in between.

Hackaday covered the beginnings of his ROV last winter. In the year since it has progressed from some sketches and a 10″ steel pipe turned into a pressure testing rig to a nearly-complete, 10 foot long, custom-lathed 4″ aluminum torpedo laying on his shop table. In a bow-to-stern walk-through [Doug] shows how he is building science equipment for less than a penny on the dollar by using largely off-the-shelf imaginatively-repurposed parts or things he could fabricate himself with only a lathe and a 3d printer.

Continue after the break for a breakdown of the tech used.

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Edge-Lit Clear Plastic Bike Combines Nighttime Riding Safety With Aurora Borealis Flair

December 18, 2014 by Rich Bremer 8 Comments

Several years ago [dan] saw some plastic frame bikes designed by MIT students. Ever since he saw those bikes he thought it would be cool to make an edge-lit plastic framed bike.

The frame is made from 1/8″ and 3/8″ thick polycarbonate sheet. The parts were designed with tongue and grooves so they fit together nicely. The joints were glued to hold everything together. Holes were drilled in the edge of the plastic large enough to fit an LED. Once the LED was inserted in the hole, it was wired up and secured with hot glue. There are about 200 LEDs on the bike, powered by a constant current LED driver circuit that [dan] designed specifically for this project.

The build process was certainly not flawless. For example, the plastic holding the bottom bracket (where the crank and pedals attach) broke. This can be avoided by increasing the amount of material in that area prior to cutting out the pieces. [dan] was able to fiberglass his broken parts back together.

[dan] admits that the bike is heavy and a little wobbly, but is definitely ride-able. He did us a favor and made all his CAD files available to anyone that wants to make one themselves. If polycarbonate is too expensive for your blood, check out this bike make from cardboard.