Balanced Design And How To Know When To Quit Optimizing

March 13, 2021 by Elliot Williams 59 Comments

I got a relatively inexpensive 6040 CNC machine, and have been spending most weekends making the thing work, and then cutting stuff, learning the toolchain, and making subsequent improvements. Probably 90% of my machine time has been on making improvements. It’s not that the machine was bad — I got the version with ballscrews and a decently solid frame — but it’s that it somehow didn’t work together as a whole. It’s just an incredibly unbalanced design.

Let’s start with the spindle motor. It’s a 2.2 kW water-cooled beast that is capable of putting tons of work into a piece and spinning at very high speed. Yet to keep up with the high speed spindle, the motors that move it around would have to be capable of high speeds as well — it’s a feeds and speeds thing if you’re not a CNC geek. And they can’t. Instead, the stepper motors that came with the kit are designed for maximum force at low speeds. Which can make sense for some machines, but for one with a slightly flexible X-axis like this one, that’s wasted as well. The frame just can’t handle the low-end grunt that the motors are capable of, so it can’t take advantage of the spindle’s power either. The design is all over the place.

Over the last two months’ of weekends, I’ve been going through this iterative procedure of asking “what is my limiting factor right now?”, working on fixing that thing up, running it some, and then asking the question again. And it’s a good general procedure, and I believe that it’s getting me to the machine I want at the minimum cost of time, money, and effort.

At first, it was the driver hardware/software with its emulated USB parallel port, so I swapped out the controller for an Arduino running GRBL, soldered directly to the DB-25 that comes out of the back. At least it can put out pulses fast enough to order the motors around, but they would still stall out at high speeds. Swapping the stepper motors out for a high-speed pair only cost me €40, which makes you wonder why they didn’t just put the right motors on in the first place. The machine now travels fast enough to make use of the high-speed spindle, and I’m flying through plywood and plastics without leaving burn marks. It’s a huge win for not much money.

The final frontier is taking big bites out of aluminum. The spindle can do it, but I fear I’m up against the frame’s rigidity on the X-axis. For whatever reason, they went with unsupported rods on the X, which are significantly more flexible than an axis that’s backed up by more metal. And this is where the limiting factor may actually be my time and patience, rather than money. I just can’t bear to disassemble and reassemble the thing again. So for now, it’s going to be small nibbles, taking advantage of the machine’s speed, if not yet the spindle’s full horsepower.

But it’s odd, because this machine is a bundle of good parts. It’s just that they haven’t been chosen to work together optimally; the frame doesn’t work with the stepper motors, which don’t work with the spindle. If they went through my procedure of saying “what’s the limiting factor?” they could have saved themselves €100 by just shipping it with a wimpier spindle, which would have been a balanced, if anemic, machine. Or they could have built it with the right motors for more speed. Or supported rails for more grunt. Or both!

I’ll never know why they quit optimizing their design when they did. Maybe they never got past the slow USB/parallel port speed? But I’m near the end of my path, and I can tell because the limiting ingredient isn’t a simple upgrade, or even mere money anymore, but my own willpower.

How can you tell when you’re at the top of a mountain in a dense fog? A step you take in any direction would lead you downhill. How can you tell when you’re satisfied with a project’s state? When you don’t have the need, or desire, to undertake the next most obvious improvement.

Hackaday Podcast 109: Cars That Suck, A Synth Packed With 555s, X-ray Letter Reading, And Pecking At A PS/2 Keyboard

March 12, 2021 by Mike Szczys 8 Comments

Hackaday editors Mike Szczys and Elliot Williams riff on the week’s most interesting hacks. It’s hard to imagine a more perfect piece of art than an original Pong circuit board mounted in a shadow box and playable along with some tasty FPGA tricks to capture the original look of the screen. You could make a synth with a 555 timer, but what about using 20 of them for perfect polyphony? We ogle an old video showing off a clever toothed-disc CNC machine for cutting pastry with a water jet. And the episode wouldn’t be complete without looking at the strange tech that goes into making a fan car.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (~60 MB)

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This Week In Security: APT Targeting Researchers, And Someone Watching All The Cameras

March 12, 2021 by Jonathan Bennett 16 Comments

Microsoft’s Patch Tuesday just passed, and it’s a humdinger. To add the cherry on top, two seperate BSOD inducing issues led to Microsoft temporarily pulling the update.

Among the security vulnerabilities fixed is CVE-2021-26897, another remote code exploit in the Windows DNS server. It’s considered a low-complexity attack, but does require local network access to pull off. CVE-2021-26867 is another of the patched vulnerabilities that sounds very serious, allowing an attacker on a Hyper-V virtual machine to pierce the barrier and run code on the hypervisor. The catch here is that the vulnerability is only present when using the Plan 9 filesystem, which surely limits the scope of the problem to a small handful of machines.

The most interesting fixed flaw was CVE-2021-26411 a vulnerability that allowed remote code execution when loading a malicious web page in either IE or pre-chromium Edge. That flaw was actively being exploited in a unique APT campaign, which we’ll cover right after the break.

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Rex Wasn’t Really A PDA, It Was The First Great Digital Rolodex

March 11, 2021 by Chris Lott 32 Comments

Back in the 1990s I was fascinated with small computers. I used the HP200LX palmtop computer for almost ten years, which I wrote about back in December. Naturally, the Franklin Rex 3 PCMCIA-sized organizer caught my attention when it was released in 1997. Here was a Personal Digital Assistant (PDA) the size of a credit card that could fit not just in your pocket, but in your shirt pocket.

Viewed today, it was an interesting paradigm. The screen takes up almost the entire front face of the device with a few buttons for navigation. But isn’t it a deal-breaker that you can’t enter or edit contact info on the device itself? This was long before cellphones were pervasive, and if you had the option to connect to the internet a telephone or Ethernet cable was involved. The ability to have a large data set in your pocket viewable without slapping a brick-like laptop on a table was pretty huge.

I think the killer feature was the PCMCIA interface. I challenged myself to reverse engineer the API so that I could sync data outside of the

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Ask Hackaday: What’s Your Favourite Build Tool? Can Make Ever Be Usurped?

March 11, 2021 by Ben James 48 Comments

What do you do whilst your code’s compiling? Pull up Hackaday? Check Elon Musk’s net worth? Research the price of a faster PC? Or do you wonder what’s taking so long, and decide to switch out your build system?

Clamber aboard for some musings on Makefiles, monopolies, and the magic of Ninja. I want to hear what you use to build your software. Should we still be using make in 2021? Jump into the fray in the comments.

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Allan McDonald’s Legacy And The Ethics Of Decision-Making

March 10, 2021 by Maya Posch 31 Comments

The Space Shuttle Challenger disaster on January 28, 1986 was a life-altering event for many, ranging from people who had tuned in to watch the launch of a Space Shuttle with America’s first teacher onboard, to the countless people involved in the manufacturing, maintenance and launching of these complex spacecraft. Yet as traumatizing as this experience was, there was one group of people for whom their dire predictions and warnings to NASA became suddenly reality in the worst way possible.

This group consisted of engineers at Morton-Thiokol, responsible for components in the Shuttle’s solid rocket boosters (SRBs). They had warned against launching the Shuttle due to the very cold weather, fearing that the O-ring seals in the SRBs at these low temperatures would not be able to keep the SRB’s hot gases from destroying the SRB and the Shuttle along with it.

Allan McDonald was one of these engineers who did everything they could to stop the launch. Until his death on March 6th of 2021, the experiences surrounding the Challenger disaster led him to become an outspoken voice on the topic of ethical decision-making, as well as a famous example of making the right decision, no matter how difficult the circumstances.

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Teardown: Go Warmer USB Rechargeable Hand Heater

March 9, 2021 by Tom Nardi 31 Comments

Under normal circumstances, if an electronic gadget in your pocket suddenly became hot to the touch, it would be cause for alarm. But not so with the Go Warmer. This lozenge shaped device is not only a USB power bank that can keep your mobile devices topped up, but is also doubles as a miniature heater that the manufacturer claims can bring its surface temperature up to 48 °C (120 °F) for several hours. You can hold in in your hand, put it in your pocket, maybe even sit on it if you’re particularly daring. The possibilities are endless, at least until the 4,000 mAh battery runs down.

For $14.99 USD, the Go Warmer certainly isn’t much of a deal when compared to other battery packs. Even if it does come with a swanky velveteen carrying pouch. But is it a good deal for one that can heat itself up without exploding? Let’s crack this metallic egg and find out.

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