Lessons In Printer Poop Recycling

The fundamental problem with multi-color 3D printing using a single hotend is that they poop an awful lot. Every time they change filaments, they’ve got to purge the single nozzle, which results in a huge number of technicolor “purge poops” which on some machines are even ejected out a chute at the back of the printer. The jokes practically write themselves.

What’s not a joke, though, is the sheer mass of plastic waste this can produce. [Stefan] from CNC Kitchen managed to generate over a kilo of printer poop for a 500-gram multi-color print. So he set about looking for ways to turn printer poops back into filament, with interesting results. The tests are based around a commercial lab-scale filament extruder, a 3Devo Composer, but should apply to almost any filament extruder, even the homebrew ones. A few process tips quickly became evident. First, purge poops are too big and stringy (ick) to feed directly into a filament extruder, so shredding was necessary.

Second, everything needs to be very clean — no cross-contamination with plastics other than PLA, no metal bits in the chopped-up plastic bits, and most importantly, no water contamination. [Stefan]’s first batch of recycled filament came from purge poops that had been sitting around a while, and sucked a lot of water vapor from the air. A treatment in a heated vacuum chamber seems to help, but what worked best was using purge poops hot and fresh from a print run. Again, ick.

[Stefan] eventually got a process down that produced decent, usable filament that would jam the printer or result in poor print quality. It even had a pretty nice color, which of course is totally dependent on the mix of colors you start with. Granted, not everyone has access to a fancy filament extruder like his, so this may not be practical for everyone, but it at least shows that there’s a path to reducing the waste stream from any printer, especially multi-material ones.

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Looking At How Pyramids Were Built Using Their Casing Stones

As one of the most famous Ancient Egyptian pyramids, the Pyramid of Khafre on the plateau of Giza has been a true wonder of the Ancient World ever since its construction around 2570 BCE. Today, well over 4,500 years later, we are still as puzzled as our ancestors over the past hundreds of years how exactly this and other pyramids were constructed. Although many theories exist, including ramps that envelop the entire pyramid, to intricate construction methods from the inside out, the only evidence we have left are these pyramids themselves.

This is where the jokingly called [History for Granite] channel on YouTube has now pitched some new ideas, involving the casing stones that used to fully cover the Pyramid of Khafre, prior to widespread theft and vandalism.

Bonding stones within the casing stones on the Pyramid of Khafre. (Credit: History for Granite, YouTube)
Bonding stones within the casing stones on the Pyramid of Khafre. (Credit: History for Granite, YouTube)

Despite the pyramids of Giza in particular being a veritable tourist trap, said tourists are heavily discouraged from climbing onto the pyramids, or even set up high-powered camera gear on tripods near them. Even with drone footage available, it was necessary to get a zoomed-in look on the casing stones that remain on the pyramid of Khafre near its top at well over 100 meters. Working within these limitations, it was possible to take detailed photos of three sides of the pyramid, which revealed interesting details.

In the top screenshot from the video the top of the pyramid is visible, which gives some indication of just how much the pyramid may have shifted out of alignment due to earthquakes over the millennia. This turned out to be not significant enough to account for some purported ‘gaps’ between the casing stones, with supposed ‘filler material’ from scaffolding holes explainable as just broken off sections of these casing stones. What was more interesting was that a pattern could be found in so-called bonding stones.

Pattern of bonding stones on the north face of the pyramid of Khafre. (Credit: History for Granite, YouTube)
Pattern of bonding stones on the north face of the pyramid of Khafre. (Credit: History for Granite, YouTube)

These bonding stones have a slanted end, so that they can be lifted slightly above a matching slanted stone, before being lowered to complete a row of bricks or stonework. After analyzing the three faces of the still mostly intact casing stones, a clear pattern emerged, such as that on the north face, pictured here.

What this suggests is that each row of casing stones were laid down by multiple groups of workers, each starting at a specific point before coming together where those sections would be joined with a bonding stone. This lends credence to the theory that the pyramid was constructed layer by layer, including the outer covering. To further examine these clues, the even older Bent Pyramid at the royal necropolis of Dahshur with mostly intact casing stones will be examined in more detail next.

If anything this series shows just how much there still is that we don’t know about these massive construction projects that are really only preceded by the works of the Sumerian and Akkadian people.

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An Intel 8008 On A Single-Board Computer

The last time we covered [Dr. Scott M. Baker], he made his Heathkit H8 run on a considerably older processor than it was made for. This time, apparently still not satisfied with the number of 8008 computers, he made an Intel 8008-based single-board computer.

The Mini-08, as [Scott] calls it, is based on his previous endeavour of downgrading the Heathkit H8. Its “CPU board” has even more memory than its predecessor at 128KiB RAM and ROM and an 8251 UART connected to a DB25 serial port. The entirely optional “display board” adds to that 10 digits of 7-segment displays, a backlit Cherry MX Blue hexadecimal keypad, a real-time clock and even a 4-voice sound generator!

[Scott] has also done an impressive job with the software, porting BASIC, FORTH, a clone of Star Trek and some utilities to his Mini-08. He demonstrates both BASIC and FORTH by printing “SCOTT WAS HERE” in a for loop and finishes off by showing how to use some of the display board with FORTH.

Like last time, he published design files and resources for you to enjoy. Overall, an interesting spin on the retro single-board computer concept.

Video after the break.

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Custom Aluminum Monitor Stand For The Home Office

Monitor stands vary wildly in price, from a few cents for a pile of books from a thrift store to hundreds of dollars. One trendy style, as [Steven Bennett] puts it, is the “General Grievous,” with adjustable arms splayed around a central pole. While effective, it is not particularly aesthetically pleasing. [Steven] set out to make his monitor stand out of extruded aluminum.

[Steven] started with a cantilever design with a VESA adapter and a c-clamp. With some 3D-printed adapter brackets, he could attach them directly to the tracks in the aluminum. Of course, the 3D printed parts, while great for prototyping, might not be the best choice for the loads he was planning on. He sent it off to a fab to get some powder-coated steel parts. After using it for a few months, he revisited the drawing board. Moving away from the cantilever with an offset center post, he switched to a single 1×4 piece of aluminum. This allowed him to create 3D-printed attachments to hold his headphones, flash drives, and cables. A build guide is available online, as well as printable add-ons.

While it doesn’t have a built-in computer like this glorious wooden stand, we can’t deny the utility or the aesthetic of the aluminum version.

Video after the break.

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BeagleV Catches Fire With The BeagleV-Fire

A new BeagleBoard is on the way, full of FPGA hotness: the BeagleV-Fire has been announced. The new $150 Single-Board Computer (SBC) from the pioneering open source BeagleBoard company is built around a RISC-V chip that has FPGA features built in. The BeagleV-Fire is built around the snappily named Microchip PolarFire MPFS025T FCVG484E, a System on a Chip (SoC) that has five Reduced Instruction Set Coding Version 5 (RISC-V) cores and a big chunk of FPGA fabric built in. That means it combines the speed of RISC-V processors with the flexibility of Field Programmable Gate Arrays (FPGA), a big pile of logic gates that can be reprogrammed.

The new BeagleV-Fire includes a sizeable chunk of FPGA to work with: the core chip includes 23 K logic elements and 68 Math blocks, plus 4 Serializer/Deserializer (SerDer) lanes that can throw about 12.7 Gbps of data into and out of the fabric. On the BeagleV-Fire, the main chip is supported by 16 GB of eMMC and 2 GB of LPDDR4 RAM, plus a micro SD slot for extra storage. Gigabit Ethernet is also included, plus USB-C power and a few serial connections for debugging. There is no WiFi built in, but there is an M.2 Key E connection were you could plug in an a wireless adapter if you need it.

Like most other BeagleBoards, the BeagleV-Fire has two headers with 92 pins, which offer access to pretty much every signal on the board, plus lots of analog to digital stuff that works with add-on boards (BeagleBoard refers to them as capes). Also present is the usual 22-pin CSI connector for attaching cameras and other devices.

Want one? They are available for immediate order on BeagleBoard.org or from the usual suspects. It looks like they are already in stock for next-day delivery. If this all sounds familiar, it’s probably because we’ve been posting about this particular board for awhile now, covering both the announcement and first tests. Continue reading “BeagleV Catches Fire With The BeagleV-Fire”

Supercon 2023 Is On: Live

Supercon is in full swing! If you weren’t able to join us in person, we’re streaming the main stage and you should absolutely check out the talks as they happen.

The full schedule is here, and you’ll find all the streams over on our YouTube channel. Come join in the fun.

For those of you are here with us in Pasadena, we’ve got a signup form for anyone who wants to submit a Lightening Talk for Sunday.

Hint: absolutely don’t miss Cory Doctorow’s keynote speech, taking place at 10:00 AM Pacific.

Saving Apollo By Decoding Core Rope

One of our favorite retro hardware enthusiasts, [CuriousMarc], is back with the outstanding tale of preserving Apollo Program software, and building a core rope reader from scratch to do it. We’ve talked about [Marc]’s previous efforts to get real Apollo hardware working again, and one of the by-products of this effort was recovering the contents of the read-only core rope memory modules that were part of that hardware.

The time finally came to hand the now-working Apollo guidance computer back to its owner, which left the team without any hardware to read core rope modules. But the archive of software from the program was still incomplete, and there were more modules to try to recover. So, the wizardly [Mike Stewart] just decided to roll up his sleeves and build his own reader. Which didn’t actually work as expected the first time.

And this leads us into one of [Marc]’s elevator music explainers, where he gives a beautiful rundown on how core rope works. And if you are thinking of core memory based on ferrite cores, get ready for a brain stretch, as core rope is quite a bit different, and is even more complicated to read. Which brings us to the bug in [Mike]’s reader, which is actually a bug in the block II design of the core rope modules.

Reading a byte off the module requires setting multiple inhibit wires to select an individual core. An innovation in block II allowed those inhibit wires to run at half current, but it turns out that didn’t actually work as intended, and partially selected multiple cores on the other half of the module. And [Mike] forget to re-implement that bug — the reader needs to literally be bug-for-bug compatible. A quick recompile of the FPGA code makes everything work again. And the conservation effort can continue. Stay tuned for more in the Apollo story!

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