It’s the little touches that make a project, and a nice nameplate can really tie a retro build together. Such badges are easy enough to make with a CNC machine, but if you don’t have access to machine tools you can put chemistry to work for you with these acid-etched brass nameplates.
The etching method that [Switch and Lever] uses to get down to brass plaques will be intimately familiar to anyone who has etched a PCB before. Ferric chloride works as well on brass as it does on copper, and [Switch and Lever] does a good job explaining the chemistry of the etching process and offers some tips on making up etching solution from powdered ferric chloride. But the meat of the video below is the head-to-head test of three different masking methods.
The first method uses a laser printer and glossy paper ripped from a magazine to create a mask. The toner is transferred to the brass using an office laminator, and the paper removed with gentle rubbing before etching. For the other two candidates he uses a laser engraver to remove a mask of plain black spray paint in one case, or to convert special laser marking paint to a mask in the other.
We won’t spoil the surprise as to which gave the best results, but we think you’ll be pleased with how easy making classy nameplates can be. You can also use electrolytic methods for a deeper etch, but we think acid etching is a little more approachable for occasional use.
Building a one-off prototype is usually pretty straightforward. Find some perfboard and start soldering, weld up some scrap metal, or break out the 3D printer. But if you’re going to do a production run of a product then things need to have a little more polish. In [Eric Strebel]’s case this means saving on weight and material by converting a solid molded part into something that is hollow, with the help of some lasagna.
What [Eric] walks us through in this video is how to build a weep mold. First, the solid part is cast in silicone. Using the cast, some “sheet clay” is applied to the inside which will eventually form the void for the new part’s walls. The clay needs to be flush with the top of the mold, though, and a trick to accomplish this task is to freeze the mold (next to the lasagna) which allows the clay to be scraped without deforming.
From there, the second half of the mold is poured in, using special channels that allow the resin to “weep” out of the mold (hence the name). This two-part process creates a much more efficient part with thin walls, rather than the expensive solid prototype part.
Real quick question: how do you increase productivity at work? The greatest (highest paid) minds would just say: do agile or scrum or something. What’s scrum? That’s where you gather ’round every morning for a waste of time meeting that kills your every desire to be productive. A while back, [Travis Goodspeed] was stuck in some lesser circle of hell like this and in an effort to be polite by not looking at his phone too much, looked at his watch too much. This led to the creation of the Goodwatch, a new bit of hardware that replaces the guts of a Casio calculator watch with a hex editor, ISM-band radio, MSP430 disassembler, and of course an RPN calculator.
[Travis] has already introduced the GoodWatch to the world. We took a look back in December but haven’t heard anything since. His talk at Shmoocon 2018 put a little more light on how this project came to be.
Some people become scientists because they have an insatiable sense of curiosity. For others, the interest is born of tragedy—they lose a loved one to disease and are driven to find a cure. In the case of Gertrude Elion, both are true. Gertrude was a brilliant and curious student who could have done anything given her aptitude. But when she lost her grandfather to cancer, her path became clear.
As a biochemist and pharmacologist for what is now GlaxoSmithKline, Gertrude and Dr. George Hitchings created many different types of drugs by synthesizing natural nucleic compounds in order to bait pathogens and kill them. Their unorthodox, designer drug method led them to create the first successful anti-cancer drugs and won them a Nobel Prize in 1988.
Becoming accomplished with a lathe is a powerful skillset, but it’s only half of the journey. Being clever comes later, and it’s the second part of the course. Patience is in there somewhere too, but let’s focus on being clever. [TimNummy] wants a knobbed bolt with critical parameters, so he makes his own. After the break, there is a sixty-second summary of the linked video.
Making stock hardware is a beginner’s tasks, so custom hardware requires ingenuity or expensive machinery. Adding finger notches to a bolthead is arbitrary with an indexing chuck, but one isn’t available. Instead, hex stock becomes a jig, and the flat sides are utilized to hold the workpiece at six intermittent angles. We can’t argue with the results which look like a part that would cost a pretty penny.
Using material found in the workshop is what being clever is all about. Hex brass stock comes with tight tolerances on the sides and angles so why not take advantage of that?
Sometimes you need something to be utterly, totally, irredeemably black. Not just a little bit black, not just really really really dark blue, but as black as it is possible to get. It might be to trap light in a camera or a telescope, for artistic purposes, or even to make your warplane a more difficult target for enemy missiles. Either way, we’re here to help, not to judge. So what are your options?
Well, first of all, there’s the much-lauded Vantablack. The name itself is a clue as to its origin – Vertically Aligned Nano Tube Arrays. It works by coating an object with a forest of carbon nanotubes in a complicated vacuum deposition process. When light hits the surface, some of it is absorbed by the nanotubes, and any that is reflected tends to be absorbed by neighbouring nanotubes rather than escaping the surface coating of the object.
Twitter is kind of a crazy place. World leaders doing verbal battle, hashtags that rise and fall along with the social climate, and a never ending barrage of cat pictures all make for a tumultuous stream of consciousness that runs 24/7. What exactly we’re supposed to do with this information is still up to debate, as Twitter has yet to turn it into a profitable service after over a decade of operation. Still, it’s a grand experiment that offers a rare glimpse into the human hive-mind for anyone brave enough to dive in.
One such explorer is a security researcher who goes by the handle [x0rz]. He’s recently unveiled an experimental new piece of software that grabs Tweets and uses them as a “noise” to mix in with the Linux urandom entropy pool. The end result is a relatively unpredictable and difficult to influence source of random data. While he cautions his software is merely a proof of concept and not meant for high security applications, it’s certainly an interesting approach to introducing humanity-derived chaos into the normally orderly world of your computer’s operating system.
Noise sampling before and after being merged with urandom
This hack is made possible by the fact that Twitter offers a “sample” function in their API, which effectively throws a randomized collection of Tweets at anyone who requests it. There are some caveats here, such as the fact that if multiple clients request a sample at the same time they will both receive the same Tweets. It’s also worth mentioning that some characters are unusually likely to make an appearance due to the nature of Twitter (emoticons, octothorps pound signs, etc), but generally speaking it’s not a terrible way to get some chaotic data on demand.
On its own, [x0rz] found this data to be a good but not great source of entropy. After pulling a 500KB sample, he found it had an entropy of 6.5519 bits per byte (random would be 8). While the Tweets weren’t great on their own, combining the data with the kernel’s entropy pool at /dev/urandom provided something that looked a lot less predictable.
The greatest weakness of using Twitter as a source of entropy is, of course, the nature of Twitter itself. A sufficiently popular hashtag on the rise might be just enough to sink your entropy. It’s even possible (though admittedly unlikely) that enough Twitter spam bots could ruin the sample. But if you’re at the point where you think hinging your entropy pool on a digital fire hose of memes and cat pictures is sufficient, you’re probably not securing any national secrets anyway.
(Editor’s note: The way the Linux entropy pool mixes it together, additional sources can only help, assuming they can’t see the current state of your entropy pool, which Twitter cats most certainly can’t. See article below. Also, this is hilarious.)
