What’s better? Harmonic or cycloidal drive? We aren’t sure, but we know who to ask. [How To Mechatronics] 3D printed both kinds of gearboxes and ran them through several tests. You can see the video of the testing below.
The two gearboxes are the same size, and both have a 25:1 reduction ratio. The design uses the relatively cheap maker version of SolidWorks. Watching the software process is interesting, too. But the real meat of the video is the testing of the two designs.
With Christmas and other end-of-year celebrations, there are gifts. The problem is that your loved ones don’t really know what to get you. Who can blame them? Do you want an Arduino, a Raspberry Pi, or a Blue Pill? Is that 3D printer on sale better than the one you have? Do you even want a second printer? They don’t know. In the best case, they’ll give you gift cards. But sometimes you just have to buy yourself something nice. [Wired] has a suggestion: a phone-based thermal camera. Which one? They have four suggestions ranging from about $150 to $200.
Different people have different reasons for wanting a thermal camera. You can see hot spots in electronics, for example. Or pick out hot water pipes behind walls. The resolution is limited. The highest in the [Wired] review is only 206×136. For the digital camera buffs, that’s 0.028 megapixels! Some cameras have even less resolution. For example, one of the cameras has an 80×60 resolution but uses an optical camera to give the illusion of a higher resolution.
[Electronoobs] has a healthy respect for the voltages and ceramics inside a microwave oven. But he still found the courage to tear one apart and show us the insides and characterize some of the components. You can see the video of the teardown below.
The danger of the voltage is obvious. However, there is also a ceramic insulator inside. Some of them are made from aluminum oxide, but others are made with beryllium oxide. You probably don’t want to inhale either one, but beryllium oxide, if powdered, can cause serious health problems. Obviously, you need to be careful if you decide to rip your oven open. Of course, the other danger is if you put the oven back together and try to use it. You need to ensure all the shielding is back in the proper place.
The video shows the operation of several of the components using test equipment and, in some cases, some surrogate components. The animation of an LC oscillator is very easy to understand. However, when he actually cuts into the magnetron with a rotary tool, you can really see how the device works. Some animations make it even clearer.
We haven’t seen a magnetron teardown for a few years. You can do many things with a magnetron from radar to vacuum deposition of films.
If you’ve ever owned a shortwave radio, you’ve probably listened at least a little to the BBC World Service. After all, they are a major broadcasting force, and with the British Empire or the Commonwealth spanning the globe, they probably had a transmitter close to your backyard. Recently, the BBC had a documentary about their early years of shortwave broadcasting. It is amazing both because it started so simply and when you think how far communications have progressed in just a scant 100 years.
Today, the BBC World Service broadcasts in over 40 languages distributing content via radio, TV, satellite, and the Internet. Hard to imagine it started with four people who were authorized to spend 10 pounds a week.
If you missed the Chumby, we’re sorry. They were relatively inexpensive Linux appliances that acted as a clock, Internet radio, and feed reader. The company went belly up, although there was some functionality remaining thanks to one of the founders and now, for a subscription fee, you can still keep your Chumby operating. However, [Doug Brown] bought one with the goal of using it for his own applications. But the 2.6.28 kernel is showing its age. So he decided to push a new kernel on the device.
If you are a Chumby enthusiast, don’t get too excited. The goal isn’t to provide the existing Chumby apps with a new kernel, [Doug] says that’s probably impossible. Instead, he wants a modern booting infrastructure and kernel on the device for his own software.
[Ben Conrad] received an interesting tool as a gift that purported to be a better mousetrap. It was a crescent wrench (made by the Crescent company, even) that didn’t have a tiny adjusting wheel like a traditional wrench. Instead, it had a slide running down the length of the handle. The idea is that you would push the slide to snug the wrench jaws against the bolt or nut, and that would be fast and easy compared to a conventional wrench. As [Ben] notes, though, it doesn’t work very well. Most of us would have just dumped it in the back of the tool chest or regifted it. [Ben] tore his apart to find out what was wrong with it.
A typical adjustable wrench has four parts. This one has 19 parts and looks like a conventional wrench with an extra slide and screw running down the length of the handle. [Ben] found the parts were poorly made, but that wasn’t the main problem.
Continue reading “Sliding Wrench Leaves A Little To Be Desired”
An accidental discovery by [3DQue] allows overhangs on FDM printers that seem impossible at first glance. The key is to build the overhang area with concentric arcs. It also helps to print at a cool temperature with plenty of fan and a slow print speed. In addition to the video from [3DQue], there’s also a video from [CNC Kitchen] below that covers the technique.
If you want a quick overview, you might want to start with the [CNC Kitchen] video first. The basic idea is that you build surfaces “in the air” by making small arcs that overlap and get further and further away from the main body of the part. Because the arcs overlap, they support the next arc. The results are spectacular. There’s a third video below that shows some recent updates to the tool.
We’ve seen a similar technique handcrafted with fullcontrol.xyz, but this is a Python script that semi-automatically generates the necessary arcs that overlap. We admit the surface looks a little odd but depending on why you need to print overhangs, this might be just the ticket. There can also be a bit of warping if features are on top of the overhang.
You don’t need any special hardware other than good cooling. Like [CNC Kitchen], we hope this gets picked up by mainstream slicers. It probably will never be a default setting, but it would be a nice option for parts that can benefit from the technique. Since the code is on GitHub, maybe people familiar with the mainstream slicers will jump in and help make the algorithm more widely available and automatic.
What will you build with this tool? If you don’t like arcs, check out conical slicing or non-planar slicing instead.
Continue reading “Arc Overhangs Make “Impossible” 3D Prints”
