For most of the history of industrial electronics, solder has been pretty boring. Mix some lead with a little tin, figure out how to wrap it around a thread of rosin, and that’s pretty much it. Sure, flux formulations changed a bit, the ratio of lead to tin was tweaked for certain applications, and sometimes manufacturers would add something exotic like a little silver. But solder was pretty mundane stuff.
Then in 2003, the dull gray world of solder got turned on its head when the European Union adopted a directive called Restriction of Hazardous Substances, or RoHS. We’ve all seen the little RoHS logos on electronics gear, and while the directive covers ten substances including mercury, cadmium, and hexavalent chromium, it has been most commonly associated with lead solder. RoHS, intended in part to reduce the toxicity of an electronic waste stream that amounts to something like 50 million tons a year worldwide, marked the end of the 60:40 alloy’s reign as the king of electrical connections, at least for any products intended for the European market, when it went into effect in 2006.
If you want to make serious assemblies out of 3D printed parts, you’ll eventually need to deal with threading. The easiest way is to make a nut trap that you can either insert a standard nut into after printing or even during printing. However, there are limitations to this method. If you want a real threaded part you can print the thread, cut the thread with a tap or bolt, or use a threaded insert. [Stefan] ran some tests to see how each of those methods held up to real use. (YouTube, embedded below.) He used fifty test parts to generate data for comparison.
We like the threaded insert method where a brass insert is pushed into the plastic while hot. Special features in the insert cause the brass part to grab the plastic, making it difficult to pull the insert out or twist it within the hole. Another thing we liked was that the tests used holes printed in the horizontal and vertical plane. You can clearly see that the orientation does alter how the holes work and fail to work.
Our recent coverage of a Raspberry Pi Zero inside the official Pi keyboard prompted a reader to point us to another far more unusual keyboard with a Pi Zero inside it. It may be a couple of years old, but [Mario Lang]’s Braille keyboard and display with built-in Pi is still an interesting project and one that should give sighted readers who have not encountered a Braille display an introduction to the technology.
The model in question is a Handy Tech Active Star 40, which seems to have been designed to have a laptop sit on top of it. A laptop was not the limit of its capabilities, because it also has a compartment with a handy USB connector that was intended to take a smartphone and thus makes a perfect receptacle for a Pi Zero. Sadly the larger boards are a little tall with their connectors.
If this hack were preformed today he would undoubtedly have used a Pi Zero W, but since the Zero he had did not possess WiFi he relied upon a Bluetooth dongle for connectivity to the outside world. The BRLTTY screen reader provides a Braille interface to the Linux console, resulting in an all-in-one Braille computer in a very compact form factor.