A little backstory may be in order for those who don’t follow [Jeroen Vleggaar]’s Huygens Optics channel on YouTube. A few months ago, he released a video discussing monolithic telescopes, where all the reflective and refractive surfaces are ground into a single thick block of glass. Fellow optical engineer [Rik ter Horst] had built a few tiny monolithic Schmidt-Cassegrain reflectors for use in cube sats, so [Jeroen] decided to build a scaled-up version himself.
The build starts with a 45 mm thick block of crown glass, from which a 50 mm cylinder is bored with a diamond hole saw. The faces of the blank are then ground into complex curves to reflect incoming light, first off the parabolic rear surface and then onto the hyperbolic secondary mirror ground into the center of the front face. A final passage through a refracting surface in the center of the rear face completes the photons’ journey through the block of glass, squeezing a 275 mm focal length into a compact package.
All this, of course, vastly understates the work required to pull it off. Between the calculations needed to figure out the surface shapes in the first place to the steps taken to machine a famously unforgiving material like glass, every step is fraught with peril. And because the design is monolithic, any mistakes mean starting all over again. Check out the video below and marvel at the skills needed to get results like this.
What strikes us most about [Jeroen]’s videos is the mix of high-tech and age-old methods and materials used in making optics, which we’ve seen him put to use to make everything from tiny Tesla valves to variable-surface mirrors.
One of the knocks that woodworkers get from the metalworking crowd is that their chosen material is a bit… compliant. Measurements only need to be within a 1/16th of an inch or so, or about a millimeter, depending on which side of the Atlantic you’re on. And if you’re off a bit? No worries, that’s what sandpaper is for.
This electronic router lift is intended to close the precision gap and make woodworking a bit less subjective. [GavinL]’s build instructions are clearly aimed at woodworkers who haven’t dabbled in the world of Arduinos and stepper motors, and he does an admirable job of addressing the hesitancy this group might feel when tackling such a build. Luckily, a lot of the mechanical side of this project can be addressed with a commercially available router lift, which attaches to a table-mounted plunge router and allows fine adjustment of the cutting tool’s height from above the table.
What’s left is to add a NEMA 23 stepper to drive the router lift, plus an Arduino to control it. [GavinL] came up with some nice features, like a rapid jog control, a fine adjustment encoder, and the ability to send the tool all the way up or all the way down quickly. Another really nice touch is the contact sensor, which is a pair of magnetic probes that attach temporarily to the tool and a height gauge to indicate touch-off. Check the video below to see it all in action.
One quibble we have with [GavinL]’s setup is the amount of dust that the stepper will be subjected to. He might need to switch out to a dustproof stepper sooner rather than later. Even so, we think he did a great job bridging the gap between mechatronics and woodworking — something that [Matthias Wandel] has been doing great work on, too.
The simple wire-loop game is often built as a fun project to teach students about electronics. [W&M Levsha] built their own version, showing off their fine crafting and machining skills and branding it as a sobriety test with the playful name “Breathalyzer.”
The mechanics of the game are quite simple. The player must guide a metal ring around the puzzle without touching it. A buzzer and light is used to indicate to the player when they’ve failed, with the project powered from a small lithium-polymer pouch cell charged via a USB port.
Where this build really shines is in the presentation, with [W&M Levsha] showing they really have what it takes to do great work in brass. Rather than a simple bent wire, we’re instead treated to a delicately-formed beam of rectangular cross-section hewn out of a single piece of metal. It’s paired with a nicely-crafted wand with a knurled handle.
Typically, nails are purpose-built things made to hold bits of wood together, with their entire design focused on that purpose. However, [W&M Levsha] went in much the other direction, crafting one very fancy expensive nail in what we can only explain as a masterful demonstration of their skills.
The build starts with a piece of brass tube, which is engraved with a delicate pattern on an automated lathe. After clean up, the spiralling lines are attractive on the polished brass.A plug is then made for the end of the tube, which gets filed into a point to resemble a nail, hiding the seam between the plug and the tube.
The tube is then threaded to accept a nail head that screws into the top, allowing the “nail” to act as a fancy little stash, which [W&M Levsha] shows off by placing a bracelet inside. The project is finished by crafting a stunning wooden box to hold the fancy nail.
We’ve seen [W&M Levsha]’s handywork before; the cap-gun cigarette lighter was a similarly impressive feat of machining and craftsmanship. Video after the break.
It’s a dedicated hacker who has the patience to build an engine from scratch. And it’s a borderline obsessed hacker who does it twice. [Meanwhile In the Garage] is of the second ilk, and in the video below the break, he takes a failed engine design and musters up the oomph to get it running.
The whole build began with an idea for a different kind of intake and exhaust valve. [Meanwhile In the Garage] dreamed up a design that does away with the traditional poppet valve. Instead of valves that open by being pushed away from their seat by a camshaft, this design uses a cylinder that is scooped so that as it rotates, its ports are exposed to either the intake or the exhaust.
During the compression stroke, the valve cylinder becomes part of the combustion chamber, with both ports facing away from the piston. If you read the comments, you’ll find that multiple people have come up with the idea through the years. With his mill, lathe, and know-how, [Meanwhile In the Garage] made it happen. But not without some trouble.
The first iteration resisted all valiant attempts at getting it started. The hour-long video preceding this one ended up in a no-start. Despite his beautiful machine work and a well thought out design, it wasn’t to be. Fire came from the engine either through the exhaust or the carburetor, but it never ran. In this version, several parts have been re-worked and the effect is immediate! The engine fired up nicely and even seems to rev up pretty well. Being a first-generation prototype, it lacks seals and other fancy parts to keep oil out of the combustion chamber. Normal engine oil has been added to the fuel as a precaution as well. The fact that it smokes quite badly isn’t a surprise and only proves that the design will benefit from another iteration. Isn’t that true for most prototypes, though?
Home-grown engines aren’t a new thing at Hackaday, and one of This Author’s favorite jet turbines used a toilet paper holder. Yes, really. Thanks to [Keith] for the Tip!
[Kent VanderVelden] has come up with an interesting AR system to assist operators who are monitoring CNC lathes. (video, embedded, below) The idea is to first produce a ‘frozen’ video stream of the workpiece. This was achieved by placing a high-speed camera above the lathe, and triggering an image capture, synchronized to the rotational position of the workpiece. A high-speed rotary encoder, attached to the tailstock via a belt drive, feeds the current position into an Altera Terasic DE-Nano FPGA eval board. This is then compared to the position from another encoder, doing duty as an angular set point control. The resulting signal is used as the camera trigger to generate a video stream of just the frames where the angle is as selected by the operator, thus giving the impression of a frozen position. The video stream is sent over to a client device based on a Raspberry Pi 4 with a UPS hat, allowing it to be portable.
This video stream is overlaid with details of the current machine position, as well as the LinuxCNC G-code being executed and a graphical representation of the operation being performed by the machine. This combined video is then fed to a Vufine VUF-110 wearable, which is minimally invasive, allowing the operator to clearly see the machine of interest. As [Kent] suggests, there are many possible usage scenarios for such a setup, including remote monitoring of multiple operating machines by a single operator.
Millimeter-wave Radars used in modern cars for cruise control and collision avoidance are usually designed to work at ranges on the order of 100 meters or so. With some engineering nous, however, experimenters have gotten these devices sending signals over ranges of up to 60 km in some tests. [Machining and Microwaves] decided to see if he could push the boat out even further, and set out machining some waveguide combiner cavities so he could use the radar chips with some very high-performance antennas.
The end goal of the project is to produce a 53 dBi antenna for the 122GHz signal put out by the mmWave radar chips commonly found in automotive applications. Working at this frequency requires getting tolerances just so in order to create an antenna that performs well.
Plenty of fine lathe work and cheerful machining banter later, and the precision waveguide is done. It may not look like much to the untrained eye, but much careful design and machining went on to make it both easy to attach to the radar and parabolic antenna system, and to make it perform at a high enough level to hopefully break records set by other enterprising radio experimenters. If that wasn’t all hard enough, though, the final job involved making 24 of these things!
There aren’t a whole lot of microwave antenna-specific machining channels on YouTube, so if you’ve been thirsty for that kind of content, this video is very much for you. If you’re more interested in antennas for lower frequencies, though, you might find some of our other stories to your liking. Video after the break.