Buying Machine Tools: Foreign Or Domestic, New Or Used?

March 21, 2018 by Quinn Dunki 141 Comments

The last time we discussed machine tools, we talked about how to choose the size of the new metalworking lathe that your wallet is itching to pour itself into. The next big decision to make is “new or used?” If you’re in North America, this question has a lot of overlap with the classic question “Import or American?”. The answer boils down to what your needs are, and what you want to get out of this machine.

If you are new to machining, and want to learn the skills, I recommend starting with an Asian import machine. If you’re careful which one you select, you’ll end up with a very reasonably priced lathe that can do precise work right out of the crate. If your interest is in learning how these tools work, and in doing a restoration project, an old American machine is a great choice. Let’s look at these two routes in more detail.

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Uber Has An Autonomous Fatality

March 20, 2018 by Al Williams 266 Comments

You have doubtlessly heard the news. A robotic Uber car in Arizona struck and killed [Elaine Herzberg] as she crossed the street. Details are sketchy, but preliminary reports indicate that the accident was unavoidable as the woman crossed the street suddenly from the shadows at night.

If and when more technical details emerge, we’ll cover them. But you can bet this is going to spark a lot of conversation about autonomous vehicles. Given that Hackaday readers are at the top of the technical ladder, it is likely that your thoughts on the matter will influence your friends, coworkers, and even your politicians. So what do you think?

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Inventing The Digital Watch Again And Again And…

March 19, 2018 by Steven Dufresne 97 Comments

In the 1950s, artwork of what the future would look like included flying cars and streamlined buildings reaching for the sky. In the 60s we were heading for the Moon. When digital watches came along in the 70s, it seemed like a natural step away from rotating mechanical hands to space age, electrically written digits in futuristic script.

But little did we know that digital watches had existed before and that our interest in digital watches would fade only to be reborn in the age of smartphones.

Mechanical Digital Watches

Cortébert jump-hour wristwatch by Wallstonekraft CC-BY-SA 3.0 — Cortébert jump-hour wristwatch.
Image by Wallstonekraft CC-BY-SA 3.0

In 1883, Austrian inventor Josef Pallweber patented his idea for a jumping hour mechanism. At precisely the change of the hour, a dial containing the digits from 1 to 12 rapidly rotates to display the next hour. It does so suddenly and without any bounce, hence the term “jump hour”. He licensed the mechanism to a number of watchmakers who used it in their pocket watches. In the 1920s it appeared in wristwatches as well. The minute was indicated either by a regular minute hand or a dial with digits on it visible through a window as shown here in a wristwatch by Swiss watchmaker, Cortébert.

The jump hour became popular worldwide but was manufactured only for a short period of time due to the complexity of its production. It’s still manufactured today but for very expensive watches, sometimes with a limited edition run.

The modern digital watch, however, started from an unlikely source, the classic movie 2001: A Space Odyssey.

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A Taste Of Who’s Speaking At Hackaday Belgrade

March 19, 2018 by Mike Szczys 1 Comment

We’re busy confirming speakers at the Hackaday Belgrade conference, taking place in Belgrade Serbia on 26 May. Now’s the time to grab a ticket and be part of something special. Here’s a teaser.

Asier Marzo // Build Principles of an Acoustic Levitator
Applications of acoustic levitation in mid-air chemistry, spectroscopy, and tissue engineering.

Vanessa Julia Carpenter // Designing for Meaningfulness in Smart Products
Creating new smart products which focus on value over function, self development, critical reflection, and behaviour change to enable meaningful experiences.

Marcel van Kervinck // Building a TTL Microcomputer without a Microprocessor
Building a small 8-bit homebrew computer out of a few dozen 1970s TTL chips, an oscillator, some RAM, and an EPROM.

Hackaday Belgrade is the hardware community you love gathered together for one exquisite weekend. Get to town Friday for a meetup at the pub, then spend a marathon Saturday enjoying the best talks, badge hacking, workshop, and live music. What we’ve just listed are of course all just the events… the real value of Hackaday Belgrade is the culture and the people that make up this community. Don’t miss it!

More Excitement to Come

Join the Hackaday Belgrade project page to get in on the live chat where we drop early info as it comes along. Also keep your eye on Hackaday, we’ll announce more speakers as we receive final confirmation. Right now we’re reviewing workshop proposals and expect to send out acceptances later this week.

Of course there’s a lot more to get really excited about. For instance, Voja Antonic and Jaromi Sukuba are hard at work on the hardware badge for the conference. It’s alive, and that’s an awful lot of switches!

Brush up on your BASIC language skills and dig that PICkit out of your tool bag. We can’t wait to see the hacks that come together with this one. If you have suggestions for features we should roll into the stock firmware, leave a comment on the badge project page!

Linux Fu: File Aliases, Links, And Mappings

March 16, 2018 by Al Williams 37 Comments

Have you heard it said that everything in Linux is a file? That is largely true, and that’s why the ability to manipulate files is crucial to mastering Linux Fu.

One thing that makes a Linux filesystem so versatile is the ability for a file to be many places at once. It boils down to keeping the file in one place but using it in another. This is handy to keep disk access snappy, to modify a running system, or merely to keep things organized in a way that suits your needs.

There are several key features that lend to this versatility: links, bind mounts, and user space file systems immediately come to mind. Let’s take a look at how these work and how you’ll often see them used.

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Building A Portable Solar-Powered Spot Welder: Nearly Practical!

March 15, 2018 by Sean Boyce 18 Comments

Last time, we covered storing and charging a 3000 Farad supercapacitor to build a solar-powered, portable spot welder. Since then, I’ve made some improvements to the charging circuit and gotten it running. To recap, the charger uses a DC-DC buck converter to convert a range of DC voltages down to 2.6 V. It can supply a maximum of 5 A though, and the supercapacitor will draw more than that if allowed to.

Capacitor charge current decreases with time as the capacitor charges. Source: Hyperphysics

After some failed attempts, I had solved that by passing the buck converter output through a salvaged power MOSFET. A spare NodeMCU module provided pulse width modulated output that switched the MOSFET on for controlled periods of time to limit the charging current. That was fine, but a constant-voltage charger really isn’t the right way to load up a capacitor. Because the capacitor plates build up a voltage as it charges, the current output from a constant-voltage charger is high initially, but drops to a very low rate in the end.

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Archimedes Would Have Known Better If He Could Count To A Million

March 14, 2018 by Brian Benchoff 78 Comments

Today is March 14th, or Pi Day because 3.14 is March 14th rendered in month.day date format. A very slightly better way to celebrate the ratio of a circle’s circumference to its diameter is July 22nd, or 22/7 written in day/month order, a fractional approximation of pi that’s been used for thousands of years and is a better fit than 3.14. Celebrating Pi Day on July 22nd also has the advantage of eschewing middle-endian date formatting.

But Pi Day is completely wrong. We should be celebrating Tau Day, to celebrate the ratio of the circumference to the radius instead of the diameter. That’s June 28th, or 6.283185…. Nonetheless, today is Pi Day and in the absence of something truly new and insightful — we’re still waiting for someone to implement a spigot algorithm in 6502 assembly, by the way — this is a fantastic opportunity to discuss something tangentially related to pi, the history of mathematics, and the idea that human knowledge builds upon itself in an immense genealogy stretching back to the beginning of history.

This is our Pi Day article, but instead of complaining about date formats, or Tau, we’re going to do something different. This is how you approximate pi with the Monte Carlo method, and how anyone who can count to a million can get a better approximation of one the fundamental constants of the Universe than Archimedes.

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