A white male in a green shirt sitting next to a tall rectangular robot made of green and black components with an aluminum frame. In front of him are a variety of components from several windshield wiper motor assemblies. Casings, gearboxes, and the like are strewn across the wooden table.

A Wiper Motor 101

February 2, 2024 by Navarre Bartz 22 Comments

Need a powerful electric motor on the cheap? [Daniel Simu] and his friend [Werner] show us the ins and outs of using windshield wiper motors.

Through many examples and disassembled components, the duo walk us through some of the potential uses of wiper motors to power a project. Some of the nuggets we get are the linear relationship of torque to current (10-15A max) and speed to voltage (12-15V DC) on these units, and some of the ways the wiring in these motors is a little different than a simple two wire DC motor.

They also discuss some of their favorite ways to control the motors ranging from a light switch to an Arduino. They even mention how to turn one into a big servo thanks to a project on Hackaday.io and a few modifications of their own. [Simu] also discusses some of the drawbacks of wiper motors, the most evident being that these motors use nylon gears which are prone to stripping or failing in other ways when subjected to high torque conditions for too long.

If you recognize [Simu], it may be from his robotic acrobat built with wiper motors. Want to see some more wiper motor hacks? How about a 3D scanner or making sure your wipers always keep the beat?

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Your Surface RT Can Become Useful Again, With Raspberry Pi OS

February 2, 2024 by Jenny List 20 Comments

Over the years there have been so many times when Microsoft came up with a product that so nearly got it right, but which tanked in the market because the folks at Redmond had more of an eye to what fitted their strategy than what the customer wanted. The Surface RT was one of these: while the hardware was at least as good if not better than Apple’s iPad, its ARM CPU and an ill-advised signed-apps-only policy meant the tablet couldn’t access the huge existing library of Windows software.

Consumers didn’t want a tablet with next-to-no apps, so it failed miserably. Never mind though, because [Michael MJD] has a video showing how an RT can be given a new life from an unlikely source, with the installation of Raspberry Pi OS.

The video pretty closely follows this guide, and involves creating a Raspberry Pi OS install medium modified with RT-specific kernel modules and device tree. It’s possible because the 32-bit ARM architecture is one of those which Raspberry Pi OS targets, and while a few things such as graphics acceleration don’t work, it’s still successful (if a little slow).

Oddly this is a technique not unlike one from the earliest days of the Raspberry Pi, when we remember people in Raspberry Pi Jams showing off the ancestor of the modern OS running on cheap ARM-based netbooks. In those cases the hack relied on transplanting the Pi userland over the device’s existing kernel, we’d be interested in an explanation of how the RT can use the Pi kernel without the famous Broadcom BLOB intended for the Pi.

We have a soft spot for the RT, as we said a good product held back by a very bad software decision. Seeing it take a new life years later is thus pleasing to us.

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Will There Be Any Pi Left For Us?

February 2, 2024 by Jenny List 72 Comments

Our world has been abuzz with the news that Raspberry Pi are to float on the London Stock Exchange. It seems an obvious move for a successful and ambitious company, and as they seem to be in transition from a maker of small computers into a maker of chips which happen to also go on their small computers, they will no doubt be using the float to generate the required investment to complete that process.

New Silicon Needs Lots Of Cash

An RP1 chip on a Raspberry Pi 5. — The most important product Raspberry Pi have ever made.

When a tech startup with immense goodwill grows in this way, there’s always a worry that it could mark the start of the decline. You might for instance be concerned that a floated Raspberry Pi could bring in financial whiz-kids who let the hobbyist products wither on the vine as they license the brand here and there and perform all sorts of financial trickery in search of shareholder value and not much else. Fortunately we don’t think that this will be the case, and Eben Upton has gone to great lengths to reassure the world that his diminutive computers are safe. That is however not to say that there might be pitfalls ahead from a hobbyist Pi customer perspective, so it’s worth examining what this could mean.

As we remarked last year, the move into silicon is probably the most important part of the Pi strategy for the 2020s. The RP2040 microcontroller was the right chip with the right inventory to do well from the pandemic shortages, and on the SBCs the RP1 all-in-one peripheral gives them independence from a CPU house such as Broadcom. It’s not a difficult prediction that they will proceed further into silicon, and it wouldn’t surprise us to see a future RP chip containing a fully-fledged SoC and GPU. Compared to their many competitors who rely on phone and tablet SoCs, this would give the Pi boards a crucial edge in terms of supply chain, and control over the software.

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Hackaday Podcast Episode 255: Balloon On The Moon, Nanotech Goblets, And USB All The Way

February 2, 2024 by Dan Maloney 13 Comments

This week, Dan joined Elliot for a review of the best and brightest hacks of the week in Episode 0xFF, which both of us found unreasonably exciting; it’s a little like the base-2 equivalent of watching the odometer flip over to 99,999. If you know, you know. We had quite a bumper crop of coolness this week, which strangely included two artifacts from ancient Rome: a nanotech goblet of colloidal gold and silver, and a perplexing dodecahedron that ends up having a very prosaic explanation — probably. We talked about a weird antenna that also defies easy description, saw a mouse turned into the world’s worst camera, and learned how 3D-printed signs are a whole lot easier than neon, and not half bad looking either. As always, we found time to talk about space, like the legacy of Ingenuity and whatever became of inflatable space habitats. Back on Earth, there’s DIY flux, shorts that walk you up the mountain, and more about USB-C than you could ever want to know.

And don’t forget that to celebrate Episode 256 next week, we’ll be doing a special AMA segment where we’ll get all the regular podcast crew together to answer your questions about life, the universe, and everything. If you’ve got a burning question for Elliot, Tom, Kristina, Al, or Dan, put it down in the comment section and we’ll do our best to extinguish it.

Grab a copy for yourself if you want to listen offline.

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The Case Against Calibration Cubes

February 2, 2024 by Danie Conradie 27 Comments

Calibration cubes have long been a staple for testing and adjusting 3D printers, but according to [Stefan] of CNC Kitchen, they’re not just ineffective—they could be leading us astray. In the video after the break he explains his reasoning for this controversial claim, and provides a viable alternative.

Such cubes are often used to calibrate the steps per millimeter for the printer’s steppers, but the actual dimensions of said cube can be impacted by over or under extrusion, in addition to how far the machine might be out of alignment. This can be further exacerbated by measuring errors due to elephant’s foot, over extruded corners, or just inaccuracies in the caliper. All these potential errors which can go unnoticed in the small 20 x 20 mm cube, while still leading to significant dimensional errors in larger prints

So what’s the solution? Not another cube. It’s something called the “CaliFlower” from [Adam] of Vector 3D. This is not a typical calibration model — it’s carefully designed to minimize measurement errors with ten internal and external measuring points with stops for your calipers. The model costs $5, but for your money you get a complete guide and spreadsheet to calculate the required of corrections needed in your firmware or slicer settings.

If you regularly switch materials in your 3D printer, [Stefan] also advises against adjusting steps per millimeter and suggests defining a scaling factor for each material type instead. With this method validated across different materials like PLA, PETG, ABS, and ASA, it becomes evident that material shrinkage plays a significant role in dimensional inaccuracy, not just machine error. While [Stefan] makes a convincing case against the standard calibration cube for dimensional calibration, he notes that is is still useful for evaluating general print quality and settings.

[Stefan] has always done rigorous testing to back his claims, and this video was no different. He has also tested the effects of filament color on part strength, the practicality of annealing parts in salt, and even printing custom filament.

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This Week In Security: Glibc, Ivanti, Jenkins, And Runc

February 2, 2024 by Jonathan Bennett 4 Comments

There’s a fun buffer overflow problem in the Glibc __vsyslog_internal() function. This one’s a real rollercoaster, because logging vulnerabilities are always scary, but at a first look, it seems nearly impossible to exploit. The vulnerability relies on a very long program name, which can overflow an internal buffer. No binaries are going to have a name longer than 1024 bytes, so there’s no problem, right?

Let’s talk about argv. That’s the list of arguments that gets passed into the main() function of every Linux binary when it launches. The first string in that list is the binary name — except that’s a convention, and not particularly enforced anywhere. What really happens is that the execve() system call sets that list of strings. The first argument can be anything, making this an attacker-controlled value. And it doesn’t matter what the program is trying to write to the log, because the vulnerability triggers simply by writing the process name to a buffer.

There is a one-liner to test for a vulnerable Glibc:

exec -a "`printf '%0128000x' 1`" /usr/bin/su < /dev/null

and the Qualys write-up indicates that it can be used for an escalation of privilege attack. The good news is this seems to be a local-only attack. And on top of that, a pair of other lesser severity issues were found and fixed in glibc while fixing this one.
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Fixing A Malfunctioning Keithley Model 179 Digital Multimeter

February 2, 2024 by Maya Posch 7 Comments

Inspired by electronics repair videos on YouTube, [Steven Leibson] recently found himself hunting down something to fix on eBay. This ‘something’ ended up being a certified classic: a Keithley Model 179 digital multimeter from 1978. Listed as non-functional, the unit arrived at his door for less than $50. There weren’t any exciting pops or smoke when he powered it on, but the display seemed to be showing nothing but random nonsense.

The Keithley Model 179 multimeter has a convenient calibration sequence printed on its electrostatic shield cover and a deadly exposed ac line fuse in the upper left part of the photo. (Image credit: Steven Leibson) — The meter has a convenient calibration sequence printed on its electrostatic shield cover and a deadly exposed AC line fuse in the upper left part of the photo.

Ultimately reviving this little piece of history was quite simple, with the main issue turning out to be a dodgy inter-board connector between the main and display boards. After admiring an old repair attempt made on the component, he removed both the male and female connectors, replacing them with new ones.

This uncovered issues with the PCB, as the FR4 material and the traces on it had begun to delaminate, probably due to the old adhesive giving up due to age. With pretty low trace density this wasn’t anything that a bit of care couldn’t work around, fortunately.

Before finding this dodgy connector, [Steven] first tried to clean the front mechanical connectors, which took multiple sessions. This was followed up by oiling the mechanism. With the connector fixed and some cleaning, the meter’s display now read correctly. It still has some issues with starting up though, which [Steven] reckons are due to the old capacitors in the device.

Presumably some recapping will round off this fun device revival experience, but for the time being a Keithley Model 179 has been saved from e-waste, to inspire generations to come.