A grey box surrounding a circular red component is mounted on an aluminium extrusion frame. The circular red face has a protrusion extending from it with a white ball bearing at the tip.

Building A Micrometer-Level Displacement Sensor With 3D Printed Parts

Every experienced machinist knows the value of taking regular measurements. If one works carefully and checks dimensions frequently, it’s possible to make a part much more precise than could be made by relying on the machine’s accuracy alone. In a similar vein, it’s possible to make a measuring device out of comparatively crude parts, as long as their behavior is well understood. Related to both principles is [BubsBuilds]’s displacement sensor, which uses a 3D printed frame but reaches precision better than two micrometers.

Admittedly the printed parts aren’t the source of the sensor’s precision, that comes from an opto-interrupter. This design has a central stylus, one end of which contacts the object under measurement. The other end flattens to a knife-edge blade, which fits between the diodes of the opto-interrupter. As the stylus point is pressed in, the blade blocks off more light from reaching the photodiode, creating an output signal proportional to displacement. To keep the stylus from twisting or moving side-to-side, two flat, circular flexures hold the stylus in the center of a cylindrical housing.

[Bubs] printed several flexure variations to see how well they resisted and permitted various torques and forces, and a symmetrical flexure design proved best for his purposes. Once the sensor was assembled, he tested it against the measurements recorded by a laser confocal displacement sensor. This design was an update from a previous version, and it improved in a few regards: the non-linearity had decreased, and the repeatability was now better than two microns, though the range had been halved. Significantly, though, it’s now much easier to mount, making this an actually practical tool.

If, however, this doesn’t fit your needs, there are many other ways to build a linear displacement sensor, ranging from capacitive to magnetostrictive. On the manual side of things, we’ve also covered a comparison of calipers.

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A More Convenient IButton Reader

iButtons are microchips housed in small, round, metal containers, and are similar to coin cell batteries in appearance. Among other things, they’re used for logging data in industrial contexts, particularly where it’s desirable to track parameters like temperature over time. [Geoffrey Wells] has worked with these sensors, and decided that the aging solutions for reading these devices are too cumbersome and out-of-date. Thus, he designed ChillPoint as a more modern solution.

As you might have guessed by the name, [Geoffrey] was inspired to build a rig specifically for inspecting iButton data loggers in cold chain logistics applications. It’s built around an ESP32-C6, which has a 1-Wire probe on the front for communicating with the target device. On contact, the reader dumps all the data, storing it on its own flash storage. The data can then further be accessed by connecting to the ChillPoint handheld device over its own WiFi access point, upon which it hosts a web UI for access. The handheld can be used for scanning iButtons single-handed, while a smartphone, tablet, or laptop can be used as a screen to monitor the results live.

The project is nearing completion, and [Geoffrey] says both the hardware and software will be open source once it’s all said and done. Anyone interested in adding a ChillPoint to their toolbox should keep an eye out for its upcoming CrowdSupply campaign.

If you find yourself working with these devices on the regular, this project may be appealing to you. We’ve looked at iButtons many times over the years. The Java Ring was probably the coolest.

SDS-Remote

SDS-Remote Brings Power-User Features To Siglent Scope

Many oscilloscopes have provisions to be connected to a computer and used remotely, but most of those interfaces are fairly rudimentary. To address this, [Winfried] has developed the SDS-Remote, a remote interface for the Siglent SDS 1000X-E series oscilloscopes.

The 1000X-E series oscilloscopes have both USB and network interfaces, and the SDS-Remote can use either (though the USB interface is still somewhat experimental). SDS-Remote allows for remote controlling the oscilloscope, capturing waveforms super handy as it lets you export a CSV file of the waveforms for further analysis. You can also capture screenshots of the scope through the web interface, making it much easier to compare waveforms as you’re working on a project. The built-in data logging lets you run long experiments and save out their results. The macro recorder lets you automate complex tests using SCPI commands and brings basic scripting to the interface without needing to run separate code. There’s also a mechanism to integrate an AI LLM to help translate common language into the correct scope configuration.

Thanks [Winfried] for sharing this awesome web interface for the oscilloscope no doubt it’ll be a welcome upgrade for those already remote controlling their Siglent scope. Head over to his GitHub page and check it out for yourself! Have you written any improved user interfaces for your equipment? Be sure to let us know what you’ve done so we can share with others who may find use in an interface that offers more than came with the product.

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Converting A Scanning Electron Microscope Into A TEM Is Surprisingly Easy

Although both a SEM and a TEM are electron microscopes, their working principles and images are very different. Whereas an SEM uses secondary electrons ejected after bombarding a sample’s surface with primary electrons, a TEM works more like an X-ray machine, with a sensor placed behind the sample to record primary electrons after they pass through said sample. It is, however, possible to turn a SEM into a TEM with some creativity, as [ProjectsInFlight] recently did with his SEM.

We previously covered how the SEM in the video was saved from being scrapped and subsequently revived, and now it is getting a pretty nice upgrade. That said, this SEM to TEM change isn’t anything new, with so-called STEM imaging having been possible for ages using a rather simple reflecting adapter. The problem here is that such adapters cost enough to make you dread filing a budget request, yet they are simple enough that you might be able to DIY one.

The main concern with the DIY adapter was clearance between the sample holder and the fragile components inside the chamber. This turned out to be a hair under 14 mm (0.55″), giving not a lot of space to work with, but that was relative to the standard bulky sample holder. With a thinner sample plate machined out of aluminum, significantly more space became available, including for the primary electron mirror and shield for the secondary electrons.

Some more lathe, milling, and tapping work later, the entire sample holder came together. During testing a hack was implemented to enable adjusting the mirror angle while in the evacuated vacuum chamber so that the adapter could be dialed-in. Subsequently, a first sample was imagined in the form of gold nanoparticles, which revealed a leaky secondary electron shield due to bypassing.

Further testing revealed that the shield needed to extend much higher to meaningfully block secondary electrons, after which the TEM image massively improved. Subsequently, a previously expired mosquito graciously donated its wings to science, with TEM imaging clearly revealing the delicate structures within these wonders of evolutionary design.

The next challenge will be to TEM image biological cells, which require substantial preparation.

This isn’t the first STEM converter we’ve seen. The SEM has a long checkered history that we’ve talked about before, too.

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Hydraulic Drive For Your Lawn Tractor

Most larger ride-around landscaping machinery has a similar transmission, a transaxle containing a gearbox, or in some cases, a continuously variable drive. [Made In Garage] has a Toro lawn tractor with just such a setup, and when the transaxle failed he replaced it with a hydraulic drive.

The video below is a classic bit of workshop porn, as he fabricates both the hubs and the rear frame to fit a pair of hydraulic motors. The throttle pedal is a hydraulic valve with the lever swapped for a pedal, and the hydraulic reservoir, in a nice touch, is an old fire extinguisher.

We’re not so sure about the pipework in such an exposed position under the machine as we think it would inevitably be damaged, but you can’t argue with the results. Having used a rough service mower with a hydraulic drive in the past, we appreciate always being exactly at the right ratio for the engine.

We think perhaps he should complement it with a loader.

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A Special Type Of Mower For Rocky Fields

Ever since wealthy European landowners started displaying vast, unused swaths of turfgrass as status symbols, regular folk have been chasing that perfectly mown and tended lawn for similar reasons. In the modern era, most mowers used to maintain these spaces use a spinning blade attached to a motor of some sort, but this can be dangerous especially on rocky fields like [Greenhill Forge] needs to mow. For these fields it’s best to use a different type of mower, and he’s built one from scratch.

This type of mower is called a flail mower, which has hinged, sharpened hammers attached to a central rotating drum. Since the flails have less rotational speed at the ends, they are less dangerous if they strike solid objects like rocks. To build one, he first builds the central drum and flails, then the enclosure to mount it to his tractor, and then a drivetrain to attach it to the tractor’s PTO. Since everything is getting built in [Greenhill Forge]’s metalworking shop, many of the parts needed to be fabricated from scratch, which involved several jigs for the plasma cutter as well as forging some steel to make some of the thicker parts.

Although not many of us have fully-stocked metalworking shops like this, it shows that almost anything can be built with the right tools. A forge is actually fairly accessible for those looking to start smithing; we’ve seen them built from little more than an off-the-shelf unmodified microwave or from a propane torch and some cookware.

See Aerodynamics In Action With A Desktop Wind Tunnel

While most of us don’t design aircraft or racing cars, it’s likely that we’re still fascinated by some of the aerodynamic studies behind them. But a full-sized wind tunnel is going to cost a small fortune, so how can we experiment? Never fear, because [luisengineering] is here with a 3D printable desktop wind tunnel.

There’s a build video that we’ve embedded below, and if you can sit through the continuous shilling of random tools, it’s an interesting watch. It’s an open design in that air is not recirculate through it, instead it passed through the machine from left to right. On the right is the fan, on the left the intake with a rectifier to ensure laminar flow. Then a constriction compresses and speeds up the air past the stage for the model under test, and an expansion slows it down again for the fan.

A wind tunnel needs a smoke generator to easily spot turbulence, and in this case a vape is called into action. The result is surprisingly effective, as we see with a demonstration using a small model car. Meanwhile if you’re interested in wind tunnels at this size, it’s not the first one we’ve brought you.

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