How to Build a Reciprocal Roof Frame (aka Mandala Roof)

March 24, 2011 by kris de decker Filed Under: Construction, DIY, Matches, Random, Roofs, Wood

How to Build a Reciprocal Roof Frame Mandala Roof

“A reciprocal roof is a beautiful and simple self-supporting structure that can be composed of as few as three rafters, and up to any imaginable quantity (within reason, of course). Reciprocal roofs require no center support, they are quick to construct, and they can be built using round poles or dimensional lumber (perhaps with some creative notching). They are extremely strong, perfect for round buildings, and very appropriate for living roofs, as well.”

How to build a reciprocal roof frame. Practice with matches first.

Related: How to build an earthbag dome.

Via Judit Bellostes.

Developed nations dangerously over-reliant on GPS

March 9, 2011 by kris de decker Filed Under: Maps, Navigation, Random

Developed nations dangerously over-reliant on GPS

“As technologies become easier to use and more cost effective their use can become almost ubiquitous. If they present a more convenient solution to an old problem, they can usurp older technologies very quickly, forcing obsolescence on otherwise excellent technologies and taking a dominant position. The use of Global Navigation Satellite Systems (GNSS) for deriving position, navigation and timing (PNT) data is such a case. The Global Positioning System (GPS) is currently the most widely used and best known example of GNSS.”

“Today, the relative ease of use of GPS in-car navigation systems means that many motorists rely entirely on GPS for navigation and if they have a road map as a back-up, it is not likely to have been used or updated in a long time. This is a trivial example of reliance on GPS with neglect of back-up systems, but the use of GPS signals is now commonplace in data networks, financial systems, shipping and air transport systems, agriculture, railways and emergency services. Safety of life applications are becoming more common.”

“One consequence is that a surprising number of different systems already have GPS as a shared dependency, so a failure of the GPS signal could cause the simultaneous failure of many services that are probably expected to be independent of each other.”

Global Navigation Space Systems: reliance and vulnerabilities (pdf). Summary.

Pay-per-swing Hammers

March 7, 2011 by kris de decker Filed Under: Books, DRM, Hammers, Libraries, Random

pay perswing hammersA reader at Metafilter reacts to the news that Harper Collins is putting a cap on the number of times their ebooks can be loaned out from libraries:

“I’ve argued that the ultimate endpoint for Digital Rights Management (DRM) is the pay-per-swing hammer. This isn’t as unlikely as it seems. Ball bearings in the hammer could be arranged, via electromagnetism, to configurations which either take away much of the force of the blow or leave it somehow off-center, or a dead-on impact. Ubiquitous wireless access will finally mean that microtransactions are more feasible. Press your fob against the hammer and, once your account has been verified, we will rearrange the bearings in the hammerhead to give you a better swing. A penny per swing. At this point, the only hard part would be getting the existing hammers out of circulation.”

Via Things Magazine. Somewhat related: Know your bolts.

How to Make an Adult Soapbox Kart

March 5, 2011 by kris de decker Filed Under: DIY, Gravity Powered Machines, Low-tech cars, Racing, Random

adult soapbox cart

“This guide will teach you the basic aspects you’ll need to consider to make yourself a road-worthy gravity-powered vehicle. Full suspension on gokart wheels, driver restraints, a ridgid frame with roll bar, and balanced drum brakes are features of the example kart I’ve built that weighs in at under 100lb.”

Of course, this thing only works downhill and is useless as a practical means of transport. But could we please get rid of the Indy 500 and the Formula One circus and race these karts instead? Seems like a lot more fun to me. Previously: DIY replicas of 1930s race cars.

Environmental Impacts of Light-Emitting Diodes (LEDs)

March 5, 2011 by kris de decker Filed Under: LEDs, Lighting, Random

leds environmental impact

Light-emitting diodes (LEDs) are advertised as environmentally friendly because they are energy efficient and mercury free. However, the material content of the LEDs, which generally include group III-V semiconductors, presents its own set of potential environmental impacts. The rapid growth in the LED industry implies that, ultimately, LEDs will contribute to the solid waste stream, and could impact resource availability, human health, and ecosystems in much the same way as generic electronic waste (e-waste) from computers and cell phones has generated concern in recent years.

Potential Environmental Impacts of Light-Emitting Diodes (LEDs): Metallic Resources, Toxicity, and Hazardous Waste Classification (pdf).

[Read more…]

Hand Operated Vacuum Cleaners

February 21, 2011 by kris de decker Filed Under: Human power, Obsolete technology, Random, Vacuum cleaners


hand operated vacuum cleaner“The easiest way to utilize pump vacuums (picture below, left) was to have two people operate them. One person would pump the vacuum while a second would use the hose and wand or tools to clean. A common sight was a daughter pumping the handle while mom did the cleaning. Most early vacuum cleaners were expensive for the time. The well-to-do often would purchase the cleaning contraptions to ease the workload of their servants or housekeepers.”


 “Bellows operated vacuums appeared in several styles and shapes. Some early vacuums utilized a single bellows. This made the cleaner less efficient because there was no suction as the bellows closed. Suction was produced only as air rushed into the bellows as it opened. To make the machines more useful, bellows were installed in pairs and offset to allow one to open while the other closed.” Picture right: a bellow-operated Star Vacuum Cleaner.

Hand operated vacuum cleaner 1“In their day, wheel operated vacuums approached the cutting edge of early technology.  They exhibited a sophistication that was not present in earlier vacuum designs.  This style of machine provided powerful and continuous suction for its user.  The increase in vacuum even allowed for larger diameter hoses and bigger cleaning tools.  Typically, one person cranked the wheel while another cleaned with a wand or hand tool.”

“Friction vacuum cleaners are based on an ingenious concept conceived by James Kirby. They utilize the driving force of the rear wheels to power the cleaner. This style of vacuum derives its power when the operator pushes it across the floor. The wheels contact the floor and turn the axle. This energy is transferred to the fan via a worm gear during every forward motion of the machine. The front wheels are connected to a brush roller to create a sweeping action. These machines look like an early electric upright vacuum, but do not need electrical current to run. As a result, they have no electric motor, cord, plug, or switch. This makes them lightweight, quiet, and cost free to use. Friction vacuums were popular well into the 1940’s in communities where electricity was not available.”

More: VacHunter galleries. Thank you, Adriana.