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A How-To In Homebrew Design, Fab, And Assembly With Structural Framing Systems

December 14, 2016 by 42 Comments

At this point, the internet is crawling with butt-kicking homebrew 3D printers made with extruded profiles, but it’s easy to underestimate the difficulty in getting there. Sure, most vendors sell a suite of interlocking connectors, but how well do these structural framing systems actually fare when put to the task of handling a build with sub-millimeter tolerances?

I’ve been playing around with these parts for about two years. What I’ve found is that, yes, precise and accurate results are possible. Nevertheless, those results came to me after I failed and–dry, rinse, repeat–failed again! Only after I understood the limits of both the materials and assembly processes was I able to deliver square, dimensionally accurate gantries that could carry a laser beam around a half-square-meter workbed. That said, I wrote a quick guide to taming these beasts. Who are they? What flavors do they come in? How do we achieve those precision results? Dear reader, read on.

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The Many Uses Of The Neon Lamp

December 12, 2016 by 44 Comments

Neon lights are that kind of nostalgic item that everybody seems to love. The neon lamp is a type of gas discharge lamp, they generate light when an electrical discharge travels through an ionized gas, or plasma. When the voltage between the electrodes exceeds certain threshold, the gas ionizes and begins conducting electricity. The basic process that generates light is the return of the ions to the ground energy state, with the emission of a photon of light. The light color depends on the emission spectra of the atoms in the gas, and also  on the gas pressure, among other variables.  Gas discharge lamps can be classified by the pressure of the gas:

  • Low pressure: includes the neon lamp, fluorescent lamps and low pressure sodium lamps.
  • High pressure: such as the metal halide, high pressure sodium and mercury vapor lamps.

Another classification comes from the heating method of the cathode:

  • Hot cathode lamps: the electric arc between the electrodes is created via thermionic emission, where electrons are expelled from the electrodes because of the high temperature.
  • Cold cathode lamps: In these, the electric arc results from the high voltage applied between the electrons, that ionizes the gas and conduction can take place.

High intensity lamps are another type of gas discharge lamp where a high power arc is formed between tungsten electrodes. Power levels of several kilowatts can be easily produced this type of lamp. Of course we can’t forget to mention nixie tubes, which are a type of cold cathode neon lamp, popular for building retro clocks. Fortunately, they are now in production again.

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Self-Driving Cars Are Not (Yet) Safe

December 5, 2016 by 123 Comments

Three things have happened in the last month that have made me think about the safety of self-driving cars a lot more. The US Department of Transportation (DOT) has issued its guidance on the safety of semi-autonomous and autonomous cars. At the same time, [Geohot]’s hacker self-driving car company bailed out of the business, citing regulatory hassles. And finally, Tesla’s Autopilot has killed its second passenger, this time in China.

At a time when [Elon Musk], [President Obama], and Google are all touting self-driving cars to be the solution to human error behind the wheel, it’s more than a little bold to be arguing the opposite case in public, but the numbers just don’t add up. Self-driving cars are probably not as safe as a good sober driver yet, but there just isn’t the required amount of data available to say this with much confidence. However, one certainly cannot say that they’re demonstrably safer.

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Glues You Can Use: Adhesives For The Home Shop

November 28, 2016 by 72 Comments

A while back I looked at lubricants for the home shop, with an eye to the physics and chemistry behind lubrication. Talking about how to keep parts moving got me thinking about the other side of the equation – what’s the science behind sticking stuff together? Home shops have a lot of applications for adhesives, so it probably pays to know how they work so you can choose the right glue for the job. We’ll also take a look at a couple of broad classes of adhesives that are handy to have around the home shop. Continue reading “Glues You Can Use: Adhesives For The Home Shop” →

Daylight Saving Time – Whys And Why Nots

November 28, 2016 by 87 Comments

We recently went through our twice yearly period of communal venting called adjusting for daylight saving time (DST), or British Summer Time (BST) as it’s called in the UK. But why are we changing the time? Seriously, who caused all this? Does it do any good? Do we still need it? And what can we do about it? As it turns out, most of us want it, as you’ll see below.

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Smartphone Bench Instrument Apps: Disappointment Or Delight?

November 17, 2016 by 24 Comments

If you are interested in electronics or engineering, you’ll have noticed a host of useful-sounding apps to help you in your design and build work. There are calculators, design aids, and somewhat intriguingly, apps that claim to offer an entire instrument on your phone. A few of them are produced to support external third-party USB instrument peripherals, but most of them claim to offer the functionality using just the hardware within the phone. Why buy an expensive oscilloscope, spectrum analyzer, or signal generator, when you can simply download one for free?

Those who celebrate Christmas somewhere with a British tradition are familiar with Christmas crackers and the oft-disappointing novelties they contain. Non-Brits are no doubt lost at this point… the crackers in question are a cardboard tube wrapped in shiny paper drawn tight over each end of it. The idea is that two people pull on the ends of the paper, and when it comes apart out drops a toy or novelty. It’s something like the prize in a Cracker Jack Box.

Engineering-oriented apps follow this cycle of hope and disappointment. But there are occasional exceptions. Let’s tour some of the good and the bad together, shall we?

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Engage Tinfoil Hat: Samsung Note 7 Battery Theory

October 24, 2016 by 144 Comments

For the most part I believe things are as they seem. But every once in a while I begin to look at notable technology happenings from a different angle. What if things are not like they seem? This is conspiracy theory territory, and I want to be very clear about this: what follows is completely fictitious and not based on fact. At least, I haven’t tried to base it on facts surrounding the current events. But perhaps you can. What if there’s more to the battery fires in Samsung’s Galaxy Note 7 phones?

I have a plausible theory, won’t you don your tinfoil hat and follow me down this rabbit hole?

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