A small, white thermal printer with a cartoon cat face above the paper outlet. It is sitting on a black mat on top of a pale wooden table. A Raspberry Pi sits nearby.

Bluetooth Printer Works With AppleTalk

For retrocomputing enthusiasts, getting old computers to work with newer peripherals can be an exciting challenge or horrible headache. If you need to print out receipts from an old Mac, you might just be in luck now that [Hamin Mousavi] has gotten AppleTalk to work with cat printers.

[Mousavi] uses a Raspberry Pi 4 here in his version of the hack, but any Bluetooth capable computer running Linux should work. His command line screenshots are from a Debian-based system, but you should be able to translate to other systems as needed.

Thanks to previous work on these thermal printers, drivers are available for them on many other systems, so the tricky part comes down to getting the web connection to the printer working through the Linux box and then getting the Mac (in this case an iMac G3) to recognize the printer as something to install.

We’ve seen people do some really interesting things with thermal printers like making them D&D tools, breaking their paper DRM, and even black and white “Polaroids.

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A cartoon of the Sun above a windmill and a solar panel with a lightning bolt going to a big grey gear with "AAAp" written on it. A small "e-" on a circle is next to it, indicating electricity transfer. Further to the right is an ADP molecule connected to a curved arrow going through the AAAp gear to turn into ATP. Three cartoon shapes, presumably illustrating biological processes are on the right with arrows pointing from the ATP.

Powering Biology With Batteries

We’ve all been there — you forgot your lunch, but there are AC outlets galore. Wouldn’t it be so much simpler if you could just plug in like your phone? Don’t try it yet, but biologists have taken us one step further to being able to fuel ourselves on those sweet, sweet electrons.

Using an “electrobiological module” of 3-4 enzymes, the amusingly named AAA (acid/aldehyde ATP) cycle regenerates ATP in biological systems directly from electricity. The process takes place at -0.6 V vs a standard hydrogen electrode (SHE), and is compatible with biological transcription/translation processes like “RNA and protein synthesis from DNA.”

The process isn’t dependent on any membranes to foul or more complicated sets of enzymes making it ideal for in vitro synthetic biology since you don’t have to worry about keeping as many components in an ideal environment. We’re particularly interested in how this might apply to DNA computing which we keep being promised will someday be the best thing since the transistor.

Maybe in the future we’ll all jack in instead of eating our daily food pill? If this all seems like something you’ve heard of before, but in reverse, maybe you’re thinking of microbial fuel cells.

An image of a man in glasses in a circle placed on a black background. The title "Pierce Nichols: Teaching Robots to Sail" is on white lettering in the bottom left corner.

Supercon 2023: [Pierce Nichols] Is Teaching Robots To Sail

Sailing the high seas with the wind conjures a romantic notion of grizzled sailors fending off pirates and sea monsters, but until the 1920s, wind-powered vessels were the primary way goods traveled the sea. The meager weather-prediction capabilities of the early 20th Century spelled the end of the sailing ship for most cargo, but cargo ships currently spend half of their operating budget on fuel. Between the costs and growing environmental concerns, [Pierce Nichols] thinks the time may be right for a return to sails.

[Nichols] grew up on a sailing vessel with his parents, and later worked in the aerospace industry designing rockets and aircraft control surfaces. Since sailing is predominantly an exercise in balancing the aerodynamic forces of the sails with the hydrodynamic forces acting on the keel, rudder, and hull of the boat, he’s the perfect man for the job.

WhileAn image of a sailing polar diagram on the left next to the words "A) Dead upwind (“in irons”) B) Close-hauled C) Beam reach (90˚ to the wind - fastest for sailing vessels D) Broad reach E) Run" The letters correspond to another diagram of a sailboat from the top showing it going directly into the wind (A), slightly into (B), perpendicular to (C), slightly away (D), and directly away from the wind / downwind (E). the first sails developed by humans were simple drag devices, sailors eventually developed airfoil sails that allow sailing in directions other than downwind. A polar diagram for a vessel gives you a useful chart of how fast it can go at a given angle to the wind. Sailing directly into the wind is also known as being “in irons” as it doesn’t get you anywhere, but most other angles are viable.

After a late night hackerspace conversation of how it would be cool to circumnavigate the globe with a robotic sailboat, [Nichols] assembled a team to move the project from “wouldn’t it be cool” to reality with the Pathfinder Prototype. Present at the talk, this small catamaran uses two wing sails to provide its primary propulsion. Wing sails, being a solid piece, are easier for computers to control since soft sails often exhibit strange boundary conditions where they stop responding to inputs as expected. Continue reading “Supercon 2023: [Pierce Nichols] Is Teaching Robots To Sail”

Print Wave Metal Casting

Direct 3D printing of metal remains out of reach for the hobbyist at the moment, so casting is often the next best thing, particularly given the limitations of 3D printed metals. [Denny] from Shake the Future shows us how to simplify the process with “print wave metal casting.”

The first step of printing a PLA object will seem familiar to any 3D print to metal process, but the main differentiator here is pouring the investment casting on the printer build plate itself. We like how he used some G-code to shake the build plate to help remove bubbles. Once the plaster solidifies, the plastic and mold are placed in the microwave to soften the plastic for removal.

The plaster is dried in an oven (or air fryer) and then [Denny] bolts the mold together for the casting process. Adding a vacuum helps with the surface finish, but you can always polish the metal with a generous helping of elbow grease.

If [Denny] seems familiar, you might remember his very detailed breakdown of microwave casting. We’ve seen plenty of different approaches to metal casting over the years here. Need a part in another material? How about casting concrete or resin?

Thanks to [marble] on the Hackaday Discord for the tip!

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Amputation and wound care behavior in C. floridanus (A) Illustration of a worker providing wound care on a femur-injured individual. (B) A worker amputating (biting) the injured leg at the trochanter. (C) A worker providing wound care on the newly created trochanter wound after amputation. (D) Percentage of amputations performed on ants with an infected or sterile femur (red) or tibia (blue) injury after 24 h. Numbers above the bars represent the sample size for each treatment. (E) Percentage of time the injured ant received wound care behavior over 3 h, binned in 10 min intervals, with a local polynomial regression (loess) showing a 95% confidence interval for the first 3 h after the experimental femur injury (femur, red: n = 8) and the first 3 h after amputation on the trochanter wound (trochanter, brown: n = 7).

Surgery — Not Just For Humans Anymore

Sometimes, a limb is damaged so badly that the only way to save the patient is to amputate it. Researchers have now found that humans aren’t the only species to perform life-saving amputations. [via Live Science]

While some ants have a gland that secretes antimicrobial chemicals to treat wounds in their comrades, Florida carpenter ants have lost this ability over the course of evolution. Lacking this chemical means to treat wounds, these ants have developed the first observed surgery in an animal other than humans.

When an ant has a wounded leg, its fellow ants analyze the damage. If the femur is the site of the wound, the other ants removed the damaged limb in 76% of cases by biting it off, while tibial wounds were treated in other ways. Experimental amputations of the tibia by researchers showed no difference in survivability compared to leaving the limb intact unless the amputation was performed immediately, so it seems the ants know what they’re doing.

Maybe these ants could be helpful surgical aids with some cyborg additions since they’ve already got experience? Ants can help you with programming too if that’s more your speed.

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A green hat with a grey zipper is partially opened revealing the grey mesh inside. It is held by two hands manipulating the zipper. The picture is inside a red circle overlaid on top of a tinted image of a workshop. A red line points to an image of a woman looking to the right wearing the green baseball cap.

Bring Your Reusable Grocery Bag On Your Head

After decades of taking plastic bags for granted, some places now charge for them to help offset some of the environmental damage they cause. If you have a tendency to forget your reusable bags at home but love to wear hats, [Simone Giertz] has the bag hat for you.

Having conquered everything from making the first Tesla pickup to a tambour puzzle table, a hat that can turn into a grocery bag seems like a relatively easy challenge. It was not. One thing that [Giertz] observes early in the process is that fabric is a much less “honest” material since it can move in ways that many of the other materials she works with cannot, like glass or wood.

As with any good project, there are numerous iterations of the bag hat, mostly due to trying to balance the two distinct functions of bag and hat without overly-compromising either. In the end, the hat features a zipper down the center from ear to ear that opens up into a mesh grocery bag. The adjustable loop of the hat does double duty as the bag handle.

If you’d like to build your own sewing machine for projects like this, maybe you should find out how they work. If you’d rather just get on with the sewing bit, we can help you with that too.

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A man in a red plaid shirt draped over an olive t-shirt holds sandpaper in one hand an an aluminum tube filled with white beads in the other over a wooden table.

Activated Alumina For Desiccating Your Filament

When you first unwrap a shiny new roll of filament for your FDM printer, it typically has a bag of silica gel inside. While great for keeping costs low on the manufacturing side, is silica gel the best solution to keep your filament dry at home?

Frustrated with the consumable nature and fussy handling of silica gel beads, [Build It Make It] sought a more permanent way to keep his filament dry. Already familiar with activated alumina beads, he crafted a desiccant cylinder that can be popped into the oven all at once instead of all that tedious mucking about with emptying and refilling plastic capsules.

A length of aluminum intake pipe, some high temperature epoxy, and aluminum mesh are all combined to make a simple, sealed cylinder. During the process, he found that using a syringe filled with the epoxy led to a much more precise application to the aluminum cylinder, so he recommends starting out that way if you make these for yourself.

We suspect something with a less permanent attachment at one end would let you periodically swap out the beads if you wanted to try this hack with the silica beads you already had. Perhaps some kind of threaded pipe fitting? If you want a more active dryer, try making one with a Peltier. If you want to know just how dry your filament is getting, you could also put in a sensor. You might also wonder, do you really need to dry filament at all?

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