You Can Now Run MS-DOS Applications On The Apple IIe

March 25, 2026 by Maya Posch 1 Comment

After a lot of debugging, [Seth Kushniryk] has managed to get the last issuess shaken out of his port of MS-DOS 2.0 to the Apple II, and has released the project to the public. If you have the requisite AD8088 or similar co-processor expansion card with onboard x86 CPU, this should be all you need to get started.

Although this co-processor card contains effectively a self-contained x86 system, its only I/O goes via the expansion bus, so it has to play nice with the 6502 CPU of the Apple II system. When we last reported on [Seth]’s efforts he had just managed to get MS-DOS 2.0 booting and basically in a barebones working state.

Since then he’s been working on the bridge program that provides communication between the 8088 on the card and the Apple II’s 6502, relocating it in RAM to enable high-resolution graphics, as well as other tweaks and optimizations. Also a lot of bug hunting, including an undocumented ProDOS constraint with a request count.

With all of this done it’s now possible to run basically any MS-DOS 2.0 compatible software, assuming it doesn’t try to write directly to video memory. This does limit the software selection somewhat, but back in the day it would probably have been amazing to have that 8 MHz 8088 purring along the 6502 to run both Apple and DOS software titles. Props to [Seth] for restoring this software functionality that had been lost to the ages.

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3D Printed Robot Arm Built For Learning Purposes

March 24, 2026 by Lewin Day No comments

If you want to work with robots you can do all sorts of learning with software and simulation, but nothing quite beats getting to grips with real machinery. That was the motivation for [James Gullberg] to build this impressive robot arm.

Featuring six degrees of freedom, the robot arm is mostly constructed of 3D printed components. This let [James] experiment with a wide variety of joint and reducer designs for the sake of learning and investigation. The base of the robot uses a fairly conventional planetary gear drive, while shoulder and elbow joints rely on split-ring planetary gearboxes to allow for high torque density with regards to size. [James] implemented a neat sensing technique here, integrating alternating magnets into the output ring gear which are monitored via a magnetic encoder. The wrist joint switches things up again, running via an inverted belt differential.

Running the show is an STM32 microcontroller, which talks to all the encoders, communicates with a Raspberry Pi over CAN bus, and handles all the necessary PID control loops and step generation for the drive motors. The plan is to run higher-level control on the Raspberry Pi which will run a ROS 2-based software stack. Already, the various joints look smooth and impressive in motion.

If you’re looking to learn about robot arms, you really can’t beat building one. We’ve featured a few projects along these lines before. Most of them aren’t exactly production-line ready, but they will teach you a ton about control, motion planning, and all sorts of associated skills. That experience can be invaluable if you intend to work with robots in industry.

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Testing Expensive Graphene-Reinforced Nylon Filament

March 24, 2026 by Maya Posch 2 Comments

Although usually nylon (generally PA6) filament is pretty cheap, there are some more exotic variants out there, such as the PA12-based Lyten 3D graphene filament that comes in at a cool $150 for a 1 kg spool. Worse for [Dr. Igor Gaspar] here was that the company doesn’t ship to the EU, and didn’t respond to emails about obtaining a sample for testing. Fortunately he got a spool via a different route, so that he could test whether this is the strongest nylon filament or not.

The full name for this filament is PA1205, though it’s not certain what the ’05’ part stands for. PA12 is a less moisture-sensitive version of PA6, however. Among the manufacturer’s claims are that it’s the strongest nylon filament, as well as very lightweight and heat-resistant. Interestingly the datasheet recommends printing with an 0.6 mm nozzle, which is the only major deviation from typical nylon FDM filaments. Of course, printing with an 0.4 mm nozzle had to be tried.

With a standard PA-CF preset in Bambu Lab’s slicer the printing of test parts worked without issues, which was promising. With load testing the filament made a good showing compared to average PA filaments, though as with most fiber reinforced filaments it’s more brittle than the pure material. Compared to PA-CF this PA1205 was much less brittle than PA-CF, however. Overall it’s not a bad filament, but for the asking price it’s a tough ask.

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Heating A Woodshop With Sawdust

March 24, 2026 by Bryan Cockfield 10 Comments

Most carpenters and woodworkers find themselves with the problem of disposing of all the sawdust they create when performing their craft. There are lots of creative solutions to this problem, such as adding it compost, using it as groundcover in a garden, adding it as filler in a composting toilet, or pressing it into bricks to burn in a stove. All of these have their uses, but involve either transporting the sawdust somewhere or performing some intermediate step to process it. [Greenhill Forge] wanted to make more direct use of it so he built this stove which can burn the sawdust directly and which provides enough heat for his woodshop.

The design is based on one which is somewhat common in Japan and involves building a vessel with a central tube for airflow, with the sawdust packed around it. The tube is made from a hardware cloth or screen to allow air to reach the sawdust. The fire is lit from the top, closed, and then allowed to burn through the stack. [Greenhill Forge] welded the entire stove from various pieces of sheet metal and bar stock, with a glass plate at the top of the stove to close off the fire and a baffle to control the airflow and rate of burn.

Initially, [Greenhill Forge] thought that the fire would burn from the top down, but this turned out to create a smoldery, messy fire instead of a hot, clean burn. Eventually, though, an ember fell down to the bottom and let the stack burn from the top up, and then it started generating serious heat. He estimates that with around 5 kg of sawdust burning for three hours that it’s about equivalent to a 6 kW stove. While a woodworker might not have enough sawdust to run this stove every day, it could be good to have on hand to use once every few weeks when the sawdust builds up enough. [Greenhill Forge] has been hard at work building unique wood burning stoves lately, like this one we recently featured which generates and then uses charcoal as fuel.

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US FCC Prohibits Approval Of New Foreign-Made Consumer Routers

March 24, 2026 by Maya Posch 50 Comments

The US Federal Communications Commission (FCC) is tasked with regulating both wired and wireless communications, which also includes a national security component. This is how previously the FCC tossed networking gear made by Huawei and foreign-manufactured drones onto its Covered List, effectively banning it from sale in the US. Now foreign-made consumer routers have been added to this list, barring explicit conditional approval on said list that would exempt them during a ‘transition phase’.

As per the FCC fact sheet, this follows after determination by an interagency body that such routers “pose unacceptable risks to the national security of the United States [..]”. This document points us to the National Security Determination PDF, which attempts to lay out the reasoning. In it is noted that routers are an integral part of every day life, and compromised routers are a major risk factor, ergo it follows that only US-manufactured routers are to be trusted.

These – so far fictional – US-manufactured consumer routers would have to feature ‘trusted supply chains’, which would seem to imply onshoring a large industrial base, though without specifying how deep this would have to go it’s hard to say what would be involved. The ‘supporting evidence’ section also only talks about firmware-related vulnerabilities, which would imply that US firmware developers do not produce CVEs.

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Using A Fiber Laser To Etch 0.1 Mm PCB Traces

March 24, 2026 by Maya Posch 9 Comments

Creating PCBs at home is quite easy these days (vias not withstanding), but even the best DIY methods usually can’t match the resolution offered by commercial PCB production lines. Large traces are easy enough to carve out of copper-backed FR1 or FR4 with even a mill, what if you need something more like 100 µm sized traces with similar clearance? This is what [Giangix] has been experimenting with, using both a fiber laser and chemical etching to see what approach gives the best results.

The thin copper clad boards are put on the 20 Watt fiber laser and held in place with the vacuum table that [Giangix] previously made, using the power of suction to make sure the board doesn’t move. The used laser specifies a minimum line width of 0.01 mm, so that’s clearly fine enough to engrave away the chemical resist layer that is sprayed on top of the copper layer.

After some experimentation, it was found that increasing the trace clearance between the 0.1 mm traces to a hair above 0.1 mm was necessary for the subsequent chemical etching step to work the best, as otherwise some copper was still likely to remain. The chemical etching bath mixture consists of hydrochloric acid and hydrogen peroxide, in a ratio of 2 mL water to 2 mL 30% HCl and 2 drops of 35% H2O2. This is agitated for 90 s to get a pretty good result.

Although the final resistance measurements on the traces is a bit higher than theoretical, comments suggest that maybe some of the copper got removed along with the removal of the resist layer. Perhaps the most interesting question here is whether directly ablating the copper using the fiber laser would give even better results and bypass the etching chemicals.

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