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CNC Scroll Saw Makes Promising First Cuts

4 de juny, per  Tom Nardi[ —]

When we talk about CNC machines, we almost invariably mean a computer controlled router. Naturally you can do other forms of automated cutting, say using a laser or a water jet, but what about adding computer control to other types of saws? [Andrew Consroe] recently put together a postmortem video about this experimental CNC scroll saw. While he never quite got it working reliably, we think his approach is absolutely fascinating and hope this isn’t the last we see of the idea.

Those who’ve used a scroll saw in the past might immediately see the challenge of this build: while a router bit or laser beam can cut in any direction, a scroll saw blade can only cut in one. If you tried to make a sharp turn on a scroll saw, you’ll just snap the fragile blade right off. To work around this limitation, [Andrew] came up with the brilliant rotary table that can be seen in the video after the break.

By combining motion of the gantry with table rotation, he’s able to keep the blade from ever making too tight a turn. Or at least, that’s the theory. While the machine works well enough with a marker mounted in place of the blade, [Andrew] says he never got it to the point it could reliably make cuts. It sounds like positioning errors would compound until the machine ended up moving the work piece in such a way that would snap the blade. Still, the concept definitely works; towards the end of the video he shows off a couple of pieces that were successfully cut on his machine before it threw the blade.

While we’ve actually seen DIY scroll saws in the past, this is the first computer controlled one to ever grace the pages of Hackaday. While some will no doubt argue that there’s no sense building one of these now that laser cutters have reached affordable prices, we absolutely love this design and how much thought went into it. At the very least, we figure this it the beefiest doodle-drawing robot ever constructed.

Day Clock Monitors Air Quality of the Great Indoors episode download
4 de juny, per  Kristina Panos[ —]

As the world settles into this pandemic, some things are still difficult to mentally reckon, such as the day of the week. We featured a printed day clock a few months ago that used a large pointer to provide this basic psyche-grounding information. In the years since then, [Jeff Thieleke] whipped up a feature-rich remix that adds indoor air quality readings and a lot more.

Like [phreakmonkey]’s original day tripper, an ESP32 takes care of figuring out what day it is and moves a 9 g servo accordingly. [Jeff] wanted a little more visual action, so the pointer moves a tad bit every hour. A temperature/humidity sensor and a separate CO₂ sensor output their readings to an LCD screen mounted under the pointer. Since [Jeff] is keeping this across the basement workshop from the bench, the data is also available from a web server running on the ESP32 via XML and JSON, and the day clock can get OTA updates.

Need a little more specificity than just eyeballing a pointer? Here’s a New Times clock that gives slightly more detail.

Netbooks: The Form Factor Time Forgot

4 de juny, per  Lewin Day[ —]

Long ago, before smartphones were ubiquitous and children in restaurants were quieted with awful games on iPads, there was a beautiful moment. A moment in which the end user could purchase, at a bargain price, an x86 computer in a compact, portable shell. In 2007, the netbook was born, and took the world by storm – only to suddenly vanish a few years later. What exactly was it that made netbooks so great, and where did they go?

A Beautiful Combination

An Asus EEE PC shown here running Linux. You could run anything on them! Because they were real, full-fat computers. No locked down chipsets or BIOS. Just good, clean, x86 fun.

The first machine to kick off the craze was the Asus EEE PC 701, inspired by the One Laptop Per Child project. Packing a 700Mhz Celeron processor, a small 7″ LCD screen, and a 4 GB SSD, it was available with Linux or Windows XP installed from the factory. With this model, Asus seemed to find a market that Toshiba never quite hit with their Libretto machines a decade earlier. The advent of the wireless network and an ever-more exciting Internet suddenly made a tiny, toteable laptop attractive, whereas previously it would have just been a painful machine to do work on. The name “netbook” was no accident, highlighting the popular use case — a lightweight, portable machine that’s perfect for web browsing and casual tasks.

But the netbook was more than the sum of its parts. Battery life was in excess of 3 hours, and the CPU was a full-fat x86 processor. This wasn’t a machine that required users to run special cut-down software or compromise on usage. Anything you could run on an average, low-spec PC, you could run on this, too. USB and VGA out were available, along with WiFi, so presentations were easy and getting files on and off was a cinch. It bears remembering, too, that back in the Windows XP days, it was easy to share files across a network without clicking through 7 different permissions tabs and typing in your password 19 times.

Netbook sales in 2008, as a proportion of total laptop sales.

The netbook was the perfect machine for the moment. It took full advantage of modern hardware advances, and created a highly usable machine for the important job of surfing the web all day, chatting to your friends. Later models began to push the envelope, with screens pushing out to 9 and later 10 inches, packing more storage, and even featuring battery lives up to 6 hours. Back in 2008, these were crazy numbers, and having less than 20GB of storage wasn’t a liability like it is today. Finally, there was the price.  Low-tier models could be had for under $300. The buying public loved it, and sales shot through the roof. In July 2008, netbooks made up just 1% of total laptop sales. By December, they had almost a fifth of the market.

However, netbooks quickly became a victim of their own success. Hardware manufacturers didn’t appreciate them cutting into sales of higher-end models which came with larger profit margins. Microsoft and Intel began to put pressure on manufacturers to limit specifications. Windows 7 licencing costs were jacked up for any machine with a screen size over 10.1 inches, killing off a series of larger netbooks that had edged towards 12″ screens. Microsoft also floated the idea of a cut-back Windows 7 Starter edition, limited to running just 3 programs at a time. At the same time, as manufacturers sought to compete on features, prices for higher-end models began to rise, outside of the original cheap-and-cheerful brief the netbook originally had.

In the end, the real death knell for the netbook came in the form of the iPad. For the vast majority of users, what they wanted was a simple, cheap internet machine to run Facebook and browse the web. As tablet sales grew, netbook sales fell off a cliff. Trapped between a new competitor and vendors keen to block them out of the market, the netbooks quickly disappeared. In their place, subnotebooks and ultrabooks stormed in – with much larger models at over three times the price point. By 2012, the netbook was effectively dead.

Irreplaceable For The Power User

While the average user found themselves better served by a basic tablet than a tiny laptop, it’s the power users that lost the most when the netbook was killed. There’s great charm and utility in a laptop that can be easily carried with one hand without risk of being dropped or tipping over. Despite the diminutive size, many netbooks packed competent keyboards; I was easily hitting 100 words per minute on an early EEE PC 901. Combined with multiple USB ports and a full Windows install, it made an excellent portable development machine.

A netbook could be carried around in the field, and interface with all manner of hardware. Being a full-fat x86 computer, it ran IDEs, programmed Arduinos, and connected to the Web, all in one neat package. Precisely none of these things can be achieved as easily with a tablet. There are plenty of Bluetooth keyboards and adapter dongles and special apps for working with hardware, but tablets simply can’t compete with a real computer for doing real work. For a hardware hacker on the go, it was a glorious tool. And, at such a low price, it was accessible to everyone — even a broke university student.

Thankfully, hope is on the horizon. The hardware market is a different place in 2020, and the netbook concept has once again shown viability to manufacturers. To qualify as a true netbook, a machine must hold true to the original values that made them great. Machines running a mobile OS, ARM processor (although that may change in the near future as OSes continue to ramp up support), or have other software limitations are not worthy to wear the name. Compact size and low price are also key attributes.

ASUS’s early netbooks boasted great battery life. Other notebooks have caught up in recent years, but 10 years from the Vivobook is nothing to sniff at.

Models like the HP Stream and ASUS VivoBook pick up where netbooks left off. Packing just 4GB of RAM and low-end CPUs, they’re not powerful machines – but they’re not supposed to be. They’re a real computer for under $300 USD, shipping with Windows 10 S. This is an “app store” version of Windows, but can be upgraded to full WIndows 10 at no cost. With under 100GB of storage, you won’t want to load these down with all your photos, videos, and applications. But, with many of us leaving all that in the cloud anyway, it won’t hold you back.

The main competitor holding back the netbook from true glory is no longer the tablet, but the Chromebook. Running a special Linux-based OS crafted by Google, these machines are intended to be lightweight web browsers, and little more. Rather than running local apps, they’re designed to work almost solely in the cloud, with a browser-based app framework. The platform has become widely popular at the bottom end of the laptop market, crowding out the possibilities of a full netbook resurgence. They do, of course, have a hardcore Linux following that happily scrap ChromeOS for a Linux install or run them side-by-side with a healthy dose of workarounds to suit the hardware. This is where a lot of the netbook aficionados ended up when the netbook hardware standard became scarce.

An Eye To The Future

It’s unlikely that we’ll see netbooks return to the prominence they once held for those four amazing years at the turn of the last decade. The average user looking for a social media machine is best served by tablets or cut-down Chromebooks. This leaves powerusers as the primary market for the netbook, and many with larger pocketbooks will simply opt for a more powerful ultrabook instead. Pour one out for the college students, who will have to mortgage their beat-up Corolla, or else lug a bulky 15″ clunker over to their capstone project to figure out how they let the smoke out. For now, netbooks remain sleeping — may they one day rise again.

Rotary Controller Dials in PC Volume

4 de juny, per  Kristina Panos[ —]

As wonderful as mechanical keyboards are, most of the pre-fab and group buy models out there have zero media controls. If you want rotary encoders and OLED screens to show what function layer you’re working in, you’ll probably have to build your own keyboard from the ground up.

Hackaday alum [Cameron Coward] got around this problem by building an electromechanical buddy for his keyboard that works as a volume control. Now that we don’t rely on them to make phone calls, rotary dials are a fun throwback to a time that seems simpler based on its robust and rudimentary technology. This one is from a lovely burnt orange Bell Trimline phone, which was peak rotary dial and one of the idea’s last gasps before tone dialing took over completely.

Operationally speaking, [Cameron] is reading in the dial’s pulses with an Arduino Nano and using a Python script to monitor the serial connection and translate the pulses to volume control. We like that this is isn’t a volume knob in the traditional sense — it’s a game of percentages. Dialing ‘2’ gives 20% volume across all programs, and ‘8’ raises it to 80% of maximum. Need to mute? Just dial ‘0’, and you’ll begin to understand why people wanted to move on from rotary dialing. It won’t take that long, but it’s not instant. Check out the demo after the break.

This isn’t the first time we’ve seen a rotary dial used to control volume, but that’s one of the minor selling points of this rotary cell phone.

3D Printering: Sticky Resin Prints and How to Fix Them

4 de juny, per  Donald Papp[ —]

After going through all the trouble of printing a part in resin, discovering it feels sticky or tacky to the touch is pretty unwelcome. Giving the model some extra ultraviolet (UV) curing seems like it should fix the problem, but it probably does not. So, what can be done?

The best thing to do with a sticky print is to immediately re-wash it in clean isopropyl alcohol (IPA) before the UV present in ambient light cures stray resin. If the part remains sticky after it is dry, more aggressive steps can be taken.

We’ll get into those more extreme procedures shortly, but first let’s understand a bit more about how resin works, then look at how that applies to preventing and removing tacky surfaces on finished prints.

How Resin Cures, and the Need to Wash

The resin used in stereolithography (SLA) is a syrupy liquid that is UV-cured, meaning it hardens when exposed to the right wavelength of light. But this process is not a perfectly binary one where all exposed resin becomes completely solid, while unexposed resin remains equally and totally liquid. It happens in degrees, and taking advantage of this is indeed part of how SLA printers operate.

In the SLA process, objects are created one slice at a time, and each slice is a thin layer of resin selectively exposed to UV so that it becomes hard. But this curing process is not always driven to absolute completion. Some of the resin in a layer remains in what is called a green state, which can be thought of as solid but not fully cured. This gives the next layer something to bond to. Each subsequent layer bonds with the previous one, and the UV hardens not just the current layer, but also further cures previous ones as the UV penetrates into the model.

The result of this process is a solid object with no distinct layers that is also covered in uncured resin from the build tank. This excess resin needs to be rinsed away with a solvent, usually isopropyl alcohol (IPA). Some resins get additional curing time by placing them in a UV cure box (or in a pinch, left in sunlight.)

Ideally this process results in a perfectly clean part, but this is not always the case. Uncured resin progressively contaminates the IPA used to wash parts, and it clings to some spots on a model more than others. Just as with hands, incomplete washing is asking for trouble.

Left-Behind Resin Makes Sticky Prints

If enough uncured (or partly-cured) resin is left behind after part washing, it contaminates a print’s surface and makes it sticky. This happens in one or both of the following ways:

  • The IPA used to wash parts is dirty. The more parts are washed in a quantity of IPA, the higher the concentration of resin in the IPA becomes. Parts washed in this IPA get coated with a thin layer of diluted resin. The alcohol evaporates, and the resin is left behind. If the concentration is high enough, the part is sticky. Not all resins are alike, and Formlabs uses their own proprietary resins, but according to them, when IPA’s resin concentration reaches 5% to 10%, parts may feel tacky.
  • Part washing was incomplete. In general, uncured resin clings more stubbornly to a textured surface. A wash process that reliably rinses resin off a smooth print might not be sufficient to fully remove resin from a print with nooks, crannies, or recessed features.

If the concentration of resin diluted in IPA is too high, the whole part will feel uniformly sticky. If the problem is resin left behind in problem spots, only those areas will feel sticky.

I’ll discuss prevention of sticky prints first, then explain how to salvage a stubbornly-sticky print.

Stopping Sticky Prints in the First Place

The following will help minimize the risk of leaving uncured or partially-cured resin on a print by helping ensure better part washing, and more efficient use of IPA.

Wash The Part Twice, Using Separate Bins

Homemade part washer using plastic bin and a cheap magnetic stirrer.

Instead of using only one container of IPA to wash parts, use two separate ones. One is exclusively for an initial washing. After the initial wash — during which most of the resin will be rinsed off — transfer the print directly to the second bin for a final cleaning. The IPA in the second bin will stay cleaner for longer, and do a better job of getting the part clean.

This process also uses less IPA in the long run, compared to a single wash bin of IPA that must be changed out whenever the resin concentration gets too high. With two bins, the primary wash IPA does get dirtier faster, but even “dirty” IPA can do a good job of removing the bulk of uncured resin from a fresh print. The IPA in the second bin, reserved only for finishing, also lasts longer because it has less resin to deal with. When the time comes to refresh the alcohol, use the IPA from the secondary bin as the new primary wash.

Simple containers with lids that can be sealed make good wash bins. Agitation of the IPA, either by shaking the container gently or by stirring, makes washing much more effective.

Target Problem Parts For Extra Washing

Simple wash bottle, operated by squeezing with one hand.

Some part geometries are simply harder to get clean. Troublesome features include:

  • Pockets, recesses, or textured areas. IPA will flow poorly in and around such features, and uncured resin will tend to stick.
  • Tubes, holes or similar internal features where IPA flow is restricted.
  • Areas of very dense supports can prevent easy flow of IPA to parts of the model.

Parts can get some extra washing by:

  • Allowing more wash time than usual.
  • Agitating the wash. Automatic part washers stir the IPA to accomplish this.
  • Rinsing with a wash bottle filled with clean IPA.

Different resins have different properties as well: some are easier and some are harder to rinse away. A process that works for some parts and resins may not be sufficient for others.

It may be tempting to give parts a very generous amount of time to soak to ensure a better rinse, but this can invite other problems if carried too far. As prints soak in IPA, they absorb the alcohol and will begin to swell. Over-soaking a part may result in a poor surface finish, or damage fine features.

Compensate for Dirty IPA with Longer Wash Times

In general, the “dirtier” the IPA is, the longer the part should be washed to compensate. But this only works to a certain extent; if IPA contains a high enough concentration of diluted resin, parts will always come out sticky. When this happens, it’s time for fresh IPA. In the meantime, giving a part a final rinse in clean IPA will do the trick, even if it’s just from a wash bottle.

Keep a Wash Bottle Handy

If you don’t own one, you should. They can be used with one hand and are great for getting IPA into specific places, and in controlled amounts.

Fixing a Stubbornly Sticky Print

The inner surface of this object remained slightly tacky despite agitated washing and additional curing. Brushing and rinsing with clean IPA was needed to remove the residue, which clung stubbornly to the small recesses.

If prevention has failed, it may be tempting to banish the model to a UV cure box (or leave it out in sunlight) for extra UV exposure in an effort to harden the sticky layer on the surface. In my experience, doing this has never given a satisfactory result. What has reliably worked for me is the following process:

  1. If possible, re-wash a sticky part immediately in clean IPA before any residual resin cures in ambient light. Allow the print to dry, and see if the problem is solved.
  2. If the part is still sticky, rinse again with clean IPA and brush with a soft and maneuverable brush such as a toothbrush. This will scrub away any stubborn, partially-cured resin clinging to the surface. Focus on problem areas, and rinse both the brush and the part frequently.
  3. Give a final rinse in clean IPA, and allow the part to dry. If it remains tacky, repeat the brushing process.

What Else Works?

Ultrasonic cleaning using a clean IPA bath is another possible method of getting into the nooks and crannies of a print, and may be useful for delicate parts that cannot tolerate a brush, but I haven’t personally had to resort to this. What has worked for you? Any tools or methods that have been particularly helpful? Share your favorite techniques in the comments.

A Pocket Retro Computer Anyone Can Build

4 de juny, per  Tom Nardi[ —]

Not satisfied with any of the DIY retro computer kits on the market, [Leonardo Leoni] decided to make his own. Built using only the finest through-hole technology and powered by the ATmega328 microcontroller, his diminutive 8-bit computer is easy to build and even easier to develop for. Whether you’re looking to hone your BASIC skills or play some Zork on the bus, this little computer looks like a great project for anyone who has a soft spot for computing’s simpler days.

All things considered, using this tiny machine looks like it would be relatively pleasant. [Leonardo] is using a common SH1106 OLED display, and there’s a full QWERTY keyboard (with number row) done up with tactile momentary buttons. There’s very few passive components involved in the build, which is sure to be appealing to new players; especially after they’ve finished soldering all those switches to the board.

On the software side, [Leonardo] says he leaned heavily on open source projects to get his machine up and running. Beyond the hardware drivers for things like the display, he specifically calls out the Tiny Basic and Tiny Lisp Computer projects for their code. If small-scale programming isn’t your style, the machine is compatible with the Arduino IDE so you can easily throw something else on it. If you’ve ever dreamed of a QWERTY Arduboy, this might be your chance.

From the way [Leonardo] describes the computer, which he calls the Cobalt 3, we get the impression a commercial kit might be in the cards. We hope the community shows enough interest to make it happen. After all, not everyone was able to make it to Hackaday Belgrade 2018 to get their own pocket retro computer.

Adding WiFi To Black Magic For Wireless GDB Action

4 de juny, per  Maya Posch[ —]

[Thoquz] wrote to us about an interesting GitHub project by [Valmantas Palikša] involving the porting of the Black Magic firmware to ESP8266. For those who are unaware, Black Magic Probe is firmware along with a range of official and third-party boards that targets the debugging of Cortex-M and Cortex-A MCUs and SoCs.

With this blackmagic-espidf project, one can use any ESP8266 board that has at least 2 MB of Flash program storage, though 1 MB should be possible if OTA updated are disabled. After flashing the firmware to the ESP8266 board, the GDB server can be reached on TCP port 2022 and UDP 2023, with a serial port available via TCP/23, UDP2323, or via the physical TX0/RX0 pins on the ESP8266.

The target board to be debugged  is hooked up by default to GPIO0 (SWDIO) and GPIO2 (SWCLK) for Serial Wire Debugging, though JTAG is also said to be supported. If set up properly, next one should be able to pop into a fresh remote GDB session:

gdb connection

If you don’t want the WiFi, you can buy a wired one, or just roll your own from any STM32 board that you’ve got kicking around.

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