Utility Mat Turns Waste Epoxy Into Useful Tools

February 9, 2023 by 46 Comments

Epoxy is a great and useful material typically prepared by mixing two components together. But often we find ourselves mixing too much epoxy for the job at hand, and we end up with some waste left behind. [Keith Decent’s] utility mat aims to make good use of what is otherwise waste material.

The concept is simple yet ingenious. It’s a flexible mat that serves as a mold for all kinds of simple little plastic workshop tools. The idea is that when you have some epoxy left over from pouring a finish on a table or laying up some composites, you can then pour the excess into various sections of the utility mat. The epoxy can then be left to harden, producing all manner of useful little tools.

It may seem silly, but it could save your workshop plenty of nickels and dimes. Why keep buying box after box of stir sticks when you can simply make a few with zero effort from the epoxy left from your last job? The utility mat also makes other useful nicknacks like glue spreaders, scrapers, wedges, and painter’s pyramids.

We’ve seen other great recycling hacks over the years too. Video after the break.

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The ARPANET Of Things And CMU’s History Of Networked Soda Machines

February 8, 2023 by 10 Comments

When the computer science department of Carnegie Mellon University expanded in the 1970s, this created a massive issue for certain individuals who now found that they had to walk quite a distance to the one single Coke machine. To their dismay, they’d now find that after braving a few flights of stairs, they’d find that the Coke machine (refilled randomly by grad students) was empty, or worse, had still warm Coke bottles inside. What happened next is detailed by the Coke machine itself, straight from the CMU’s servers.

A follow-up by the IBM Industrious blog adds more feedback from those responsible for we now refer to as an IoT device, though technically it was an AoT at the time, being a pre-Internet era. For the bottle-based, 1970s machine, microswitches were installed by students in the machine to keep track of the fill state of each column and for how long the bottles had been inside. After about 3 hours newly added bottles were registered as being ‘COLD’, which could be queried from the PDP-10’s mainframe (CMUA) or via ARPANET using the finger command on the special ‘coke’ user account with finger coke@cmua.

As time moved on and the coke machine was replaced  in the early 90s with a newer (and very much non-IoT) model, students would once again attempt to modify it, much to the chagrin of the Coke company’s maintenance people, resulting in the students reverting modifications prior to a maintenance appointment. This tracking system used the empty column lights on the machine, leading to a similar tracking system as on the 1970s machine, except now running on a PC-XT class computer that also tracked the status of the M&M snack machine nearby.

Whether CMU CS students can still query such highly relevant information today is not mentioned, but we presume it is an issue of paramount importance that has been addressed in an expedient fashion over the intervening years.

(Thanks to [Daniel T Erickson] for the tip)

Understanding AI Chat Bots With Stanford Online

February 8, 2023 by 8 Comments

The news is full of speculation about chatbots like GPT-3, and even if you don’t care, you are probably the kind of person that people will ask about it. The problem is, the popular press has no idea what’s going on with these things. They aren’t sentient or alive, despite some claims to the contrary. So where do you go to learn what’s really going on? How about Stanford? Professor [Christopher Potts] knows a lot about how these things work and he shares some of it in a recent video you can watch below.

One of the interesting things is that he shows some questions that one chatbot will answer reasonably and another one will not. As a demo or a gimmick, that’s not a problem. But if you are using it as, say, your search engine, getting the wrong answer won’t amuse you. Sure, you can do a conventional search and find wrong things, but it will be embedded in a lot of context that might help you decide it is wrong and, hopefully, some other things that are not wrong. You have to decide.
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Simple Wood-Fired Water Heater Is Surprisingly Effective

February 8, 2023 by 55 Comments

These days, humans have gotten all fancy-schmancy with their gas and electric water heaters. Heck, some are even using heat pumps to do the work as efficiently as possible. [HowToLou] got back to basics instead, with his simple wood-fired water heater design.

The design is straightforward, featuring 100ft of quarter-inch copper tubing wrapped directly around a steel barrel. Room-temperature water is fed into the tubing via a garden hose, and comes out much hotter, thanks to a fire burning away in the barrel stove of [Lou’s] own construction.

For an input water temperature of 41 F, the output reaches 105 F at a flow rate of 0.67 gallons per minute. By [Lou]’s calculations, that’s a heat transfer to the water of roughly 21,000 BTU per hour. [Lou] achieved this with just $55 worth of copper tubing, and he notes that simply doubling up the tubing would increase the heat transfer to the water even further.

If you’re looking for a hot shower from your outdoor wood stove, a build like this might be just the ticket. With the stove burning hot and your hose as a water supply, you could experience the joy of the hot water while you’re standing in the snow outside. We’ve seen [Lou]’s work before, too. Video after the break.

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Building A Plasma Piano Ain’t Easy

February 8, 2023 by 17 Comments

Electronic arcs can be made to “sing” if you simply modulate them on and off at audible frequencies. We’ve seen it done with single Tesla coils, and even small Tesla choirs, but [Mattias Krantz] took this to extremes by building an entire “plasma piano” using this very technique.

The build relies on ten transformers more typically used in cathode ray tubes. The transformers are capable of generating high enough voltages to create arcs in the air. The transformers are controlled by an Arduino, which modulates the arcs at musical frequencies corresponding to the keys pressed on the piano. Sensing the keys of the piano is achieved with a QRS optical sensor strip designed for performance capture from conventional pianos. For the peak aesthetic, the transformer outputs are connected to the metal hammers of the piano, and the arcs ground out on a metal plate in the back of the piano’s body. This lets arcs fly across the piano’s whole width as its played. Ten transformers are used to enable polyphony, so the piano to play multiple tones at once.

Building the piano was no mean feat for [Mattias], who admitted to having very limited experience with electronics before beginning the build. However, he persevered and got it working, while thankfully avoiding injury from high voltage in the process. This wasn’t easy, as Arduinos would regularly freeze from the noise produced by the arcs and the system would lose all control. However, with some smart software tweaks to the arc control and some insulating panels, [Mattias] was able to get the piano playable quite well with a beautiful chiptune tone.

It bears stating that HV work can be dangerous, and you shouldn’t try it at home without the proper understanding of how to do so safely. If you’re confident though, we’ve featured some great projects in this space before. Video after the break.

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An image of a Modulex brick (left) next to a LEGO brick right. Both are 4x2 studs, but the Modulex brick is much smaller at 20x10x5 mm vs the LEGO's 32x16x9.6 mm.

Modulex Is LEGO’s Long Lost Cousin

February 8, 2023 by 23 Comments

We love LEGO here at Hackaday, but did you know that LEGO spun off a parallel product line made for architectural models called Modulex?

[Peter Dibble] takes us on a deep dive through the history of Modulex, starting with Godtfred Kirk Christiansen needing a better way to model actual buildings after trying to design a house in LEGO. The LEGO brick’s 5:5:6 ratio proved challenging for modeling full-sized projects, so Modulex was conceived around a 1:1:1 ratio 5 mm cube. This change means Modulex is not compatible with LEGO System bricks.

As architectural styles morphed through the mid-20th Century, designs based around blocky shapes became passe, and Modulex pivoted to targeting factory and city planning customers. Products later branched out to include wall charts and Plancopy photocopy-able planners along with reconfigurable signage. Modulex (now ASI) still goes on as one of the biggest signage companies in the world, but discontinued the bricks in 2004. An attempt was made to revive Modulex bricks in 2015, but LEGO Group bought the company that had the rights to the bricks and has no intention of producing Modulex.

For more LEGO hacks, checkout this machine learning LEGO sorter or these giant LEGO-like pieces.

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Linux Fu: The Shell Forth Programmers Will Love

February 8, 2023 by 28 Comments

One of the most powerful features of Unix and Linux is that using traditional command line tools, everything is a stream of bytes. Granted, modern software has blurred this a bit, but at the command line, everything is text with certain loose conventions about what separates fields and records. This lets you do things like take a directory listing, sort it, remove the duplicates, and compare it to another directory listing. But what if the shell understood more data types other than streams? You might argue it would make some things better and some things worse, but you don’t have to guess, you can install cosh, a shell that provides tools to produce and work with structured data types.

The system is written with Rust, so you will need Rust setup to compile it. For most distributions, that’s just a package install (rust-all in Ubuntu-like distros, for example). Once you have it running, you’ll have a few new things to learn compared to other shells you’ve used. Continue reading “Linux Fu: The Shell Forth Programmers Will Love” →