[Kevin] admits that FreeCAD may not be the ideal tool for editing STL files. But it is possible, and he shares some practical advice in the video below. If you want to get the most out of your 3D printer, it pays to be able to create new parts, and FreeCAD is a fine option for that. However, sometimes you download an STL from the Internet, and it just isn’t quite what you need.
Unlike native CAD formats, STLs are meshes of triangles, so you get very large numbers of items, which can be unwieldy. The first trick is to get the object exactly centered. That’s easy if you know how, but not easy if you are just eyeballing it.
If you use the correct workbench, FreeCAD can analyze and fix mesh problems like non-manifold parts, flipped normals, and other issues. The example is a wheel with just over 6,000 faces, which is manageable. But complex objects may make FreeCAD slow. [Kevin] says you should be fine until the number of faces goes above 100,000. In that case, you can decimate the number of faces with, of course, a corresponding loss in resolution.
Once you are satisfied with the mesh, you can create a real FreeCAD shape from the mesh. The resulting object will be hollow, so the next step will be to convert the shape to a solid.
That still leaves many triangles when you really want flat surfaces to be, well, flat. The trick is to make a copy and use the “refine shape” option for the copy. Once you have a FreeCAD solid, you can do anything you can do in FreeCAD.
We’ve run our share of FreeCAD tips if you want more. There are other ways to tweak STLs, too.
Sleep apnea is a debilitating disease that many sufferers don’t even realize they have. Those afflicted with the condition will regularly stop breathing during sleep as the muscles in their throat relax, sometimes hundreds of times a night. Breathing eventually resumes when the individual’s oxygen supply gets critically low, and the body semi-wakes to restore proper respiration. The disruption to sleep causes serious fatigue and a wide range of other deleterious health effects.
Treatment for sleep apnea has traditionally involved pressurized respiration aids, mechanical devices, or invasive surgeries. However, researchers are now attempting to develop a new drug combination that could solve the problem with pharmaceuticals alone.
Breathe Into Me
There are a variety of conditions that fall under the sleep apnea umbrella, with various causes and a range of imperfect treatments. Perhaps the most visible is obstructive sleep apnea (OSA), in which the muscles in the throat relax during sleep. Under certain conditions, and depending on anatomy, this can lead the airway to become blocked, causing a cessation of breathing that requires the sufferer to wake to a certain degree to restore proper respiration. Since the 1980s, OSA has routinely been treated with the use of Continuous Positive Airway Pressure (CPAP) machines, which supply pressurized air to the face and throat to forcibly keep the airway open. These are effective, except for one major problem—a great deal of patients hate them, and compliance with treatment is remarkably poor. Some studies have shown up to 50% of patients give up on CPAP treatment within a year due to discomfort around sleeping with a pressurized air mask.
Obstructive sleep apnea occurs when upper airway muscles relax excessively during sleep, ultimately restricting or totally blocking the airway. Credit: Apnimed
Against this backdrop, a simple pill-based treatment for sleep apnea is a remarkably attractive proposition. It would allow the treatment of the condition without the need for expensive, high-maintenance CPAP machines which a huge proportion of patients hate using in the first place. Such a treatment is now close to being a reality, under the name AD109.
The treatment aims to directly target the actual cause of obstructive sleep apnea. OSA is a neuromuscular condition, and one that only occurs during sleep—as those afflicted with the disease don’t suffer random airway blockages while awake. When sleep occurs, neurotransmitter levels like norepinephrine tend to decrease. This can can cause the upper airway muscles to excessively relax in sleep apnea sufferers, to the point that the airway blocks itself shut. AD109 tackles this issue with a combination of drugs—an antimuscarinic called aroxybutynin, and a norepinephrine reuptake inhibitor called atomoxetine. In simple terms, the aroxybutynin blocks so-called muscarinic receptors which decrease muscle tone in the upper airway. Meanwhile, the atomoxetine is believed to simultaneously improve muscle tone in the upper airway by maintaining higher activity in the hyperglossal motor neurons that control muscles in this area.
Results in phase 2 testing showed a marked decrease in AHI compared to those taking a placebo. Credit: research paper
Thus far, clinical testing has been positive, suggesting the synergistic combination of drugs may be able to improve airflow for sleep apnea patients. Phase 1 and Phase 2 clinical trials have been conducted to verify the safety of the treatment, as well as its efficacy at treating the condition. Success in the trials was measured with the Apnea-Hypopnea Index (AHI), which records the number of airway disruptions an individual has per hour. AHI events were reduced by 45% in those taking AD109 when compared to the placebo group in a phase 2 trial featuring 211 participants. It achieved this while proving generally safe in early testing without causing detectable detriments to attention or memory. However, some side effects were noted with the drug—most specifically dry mouth, urinary hesitancy, and a level of insomina. The latter being particularly of note given the drug’s intention to improve sleep.
Testing on AD109 continues, with randomized Phase 3 trials measuring its performance in treating mild, moderate, and severe obstructive sleep apnea. For now, commercialization remains a ways down the road. And yet, for the first time, it appears promising that modern medicine will develop a simple drug-based treatment for a disease that leaves millions fatigued and exhausted every day. If it proves viable, expect it to become a major pharmaceutical success story and the hottest new drug on the market.
[Clough42] created a 3D print for a lathe tool and designed in some support to hold the piece on the bed while printing. It worked, but removing the support left unsightly blemishes on the part. A commenter mentioned that the support doesn’t have to exactly touch the part to support it. You can see the results of trying that method in the video below.
In this case [Cloug42] uses Fusion, but the idea would be the same regardless of how you design your parts. Originally, the support piece was built as a single piece along with the target object. However, he changed it to make the object separate from the support structure. That’s only the first step, though. If you import both pieces and print, the result will be the same.
Instead, he split the part into the original two objects that touch but don’t blend together. The result looks good.
We couldn’t help but notice that we do this by mistake when we use alternate materials for support (for example, PETG mixed with PLA or PLA with COPE). Turns out, maybe you don’t have to switch filament to get good results.
After the swivel by Helium Inc. towards simply running distributed WiFi hotspots after for years pushing LoRaWAN nodes, much of the associated hardware became effectively obsolete. This led to quite a few of these Nebra LoRa Miners getting sold off, with the [Buy it Fix it] channel being one of those who sought to give these chunks of IP-67-rated computing hardware a new life.
Originally designed to be part of the Helium Network Token (HNT) cryptocurrency mining operation, with users getting rewarded by having these devices operating, they contain fairly off-the-shelf hardware. As can be glanced from e.g. the Sparkfun product page, it’s basically a Raspberry Pi Compute Module 3+ on a breakout board with a RAK 2287 LoRa module. The idea in the video was to convert it into a Meshcore repeater, which ought to be fairly straightforward, one might think.
Unfortunately the unit came with a dead eMMC chip on the compute module, the LoRa module wasn’t compatible with Meshcore, and the Nebra breakout board only covers the first 24 pins of the standard RPi header on its pin header.
The solutions involved using a µSD card for the firmware instead of the eMMC, and doing some creative routing on the bottom of the breakout board to connect the unconnected pins on the breakout’s RPi header to the pins on the compute module’s connector. This way a compatible LoRa module could be placed on this header.
Rather than buying an off-the-shelf LoRa module for the RPi and waiting for delivery, a custom module was assembled from an eByte E22 LoRa module and some stripboard to test whether the contraption would work at all. Fortunately a test of the system as a Meshcore repeater showed that it works as intended, serving as a pretty decent proof-of-concept of how to repurpose those systems from a defunct crypto mining scheme into a typical LoRa repeater, whether Meshcore or equivalent.
It’s possible to improve your 3D prints in all kinds of ways. You can tune your printer’s motion, buy better filament, or tinker endlessly with any number of slicer settings. Or, as [Dirt-E-Bikes] explains, you could grab yourself some silica gel.
If you’re unfamiliar with silica gel, it’s that stuff that comes in the “DO NOT EAT” packet when you buy a new pair of shoes. It’s key feature is that it’s hygroscopic—which means it likes to suck up moisture from the atmosphere. When it comes to 3D printing, this is a highly useful property—specifically because it can help keep filament dry. Over time, plastic filament tends to pick up some moisture on its own from the atmosphere, and this tends to interfere with print quality. This can be avoided by storing filament in a sealed or semi-seaeled environment with silica gel. The gel will tend to suck up most of the moisture from the air in the sealed container, helping to keep the filament drier.
[Dirt-E-Bikes] does a great job of explaining how best to integrate silica gel with your filament spools and automatic material changer (if you have one). He also explains the value of color changing silica gel which indicates when the material is saturated with water, as well as how to dry it out for reuse. You can even combine some of the color changing beads with the more common plain white beads recycled from your shoe boxes, since you only need a few colored beads to get an idea of the water content.
If you’re gonna be a hacker eventually you’re gonna have to write software to process and generate text data. And when you deal with text data, in this day and age, there are really only two main things you need to know: 7-bit ASCII and UTF-8. In this video [Nic] explains 7-bit ASCII and Unicode, and then explains UTF-8 and how it relates to Unicode and ASCII. [Nic] goes into detail about some of the clever features of Unicode and UTF-8 such as self-synchronization, single-byte ASCII, multi-byte codepoints, leading bytes, continuation bytes, and grapheme clusters.
[Nic] mentions about UTF-16, but UTF-16 turned out to be a really bad idea. UTF-16 combines all of the disadvantages of UTF-8 with all of the disadvantages of UTF-32. In UTF-16 there are things known as “surrogate pairs”, which means a single Unicode codepoint might require two UTF-16 “characters” to describe it. Also the Byte Order Marks (BOM) introduced with UTF-16 proved to be problematic. Particularly if you cat files together you can end up with stray BOM indicators randomly embedded in your new file. They say that null was a billion dollar mistake, well, UTF-16 was the other billion dollar mistake.
tl;dr: don’t use UTF-16, but do use 7-bit ASCII and UTF-8.
Oh, and as we’re here, and talking about Unicode, did you know that you can support The Unicode Consortium with Unicode Adopt-a-Character? You send money to sponsor a character and they put your name up in lights! Win, win! (We noticed while doing the research for this post that Jeroen Frijters of IKVM fame has sponsored #, a nod to C#.)
What happens when a traditional board game company decides to break into electronic gaming? Well, if it were a UK gaming company in 1978, the result would be a Waddingtons 2001 The Game Machine that you can see in the video from [Re:Enthused] below.
The “deluxe console model” had four complete games: a shooting gallery, blackjack, Code Hunter, and Grand Prix. But when you were done having fun, no worries. The machine was also a basic calculator with a very strange keyboard. We couldn’t find an original retail price on these, but we’ve read it probably sold for £20 to £40, which, in 1978, was more than it sounds like today.
Like a board game, there were paper score sheets. The main console had die-cut panels to decorate the very tiny screen (which looks like a very simple vacuum fluorescent display) and provide labels for the buttons. While it isn’t very impressive today, it was quite the thing in 1978.
This would be a fun machine to clone and quite easy, given the current state of the art in most hacker labs. A 3D-printed case, color laser-printed overlays, and just about any processor you have lying around would make this a weekend project.
It is easy to forget how wowed people were by games like this when they were new. Then again, we don’t remember any of those games having a calculator.
As a side note, Waddingtons was most famous for their special production of Monopoly games at the request of MI9 during World War II. The games contained silk maps, money, and other aids to help prisoners of war escape.
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