This Rail Speeder Needs A Little Work

If you take the wheels off a FIAT Punto, you might just notice that those rims fit nicely on a rail. [AT Lab] did, and the resulting build makes for a very watchable video.

Some of us have been known to spend a little too much time chasing trains, and there’s little on rails that won’t catch a railfan’s eye. That goes for rail speeders too, home constructed railcarts for exploring abandoned lines, and there are some great builds out there. We like the one in the video below the break, but we can’t help noticing a flaw which might just curtail its career.

It’s a simple enough build, a wooden chassis, a single motor and chain drive to one axle. All the wheel fittings are 3D printed, which might be a case of using the one tool you have to do everything, but seems to work. It rides well on the test track which appears to be an abandoned industrial siding, but it’s in those wheels we can see the problem and we guess that perhaps the builder is not familiar with rails. The Punto wheels have an inner rim and an outer rim, while a true rail wheel only has an inner one. There’s a good reason for this; real railways have points and other trackwork, not to mention recessed rails at road crossings or the like. We love the cart, but we’d cut those inner rims off to avoid painful derailments.

If you’re up for the ultimate railway build, take care not to go near a live line, and make sure you follow this video series.

Continue reading “This Rail Speeder Needs A Little Work”

Street with polluted smoggy air

Serious Chemical Threat Sniffer On A Budget

Chemical warfare detection was never supposed to be a hobbyist project. Yet here we are: Air Quality Guardian by [debdoot], the self-proclaimed world’s first open source chemical threat detection system, claims to pack lab-grade sensing into an ESP32-based build for less than $100. Compare that with $10,000+ black-box hardware and you see why this is worth trying at home, even if this project might not have the nut cracked just yet.

Unlike your air monitor from IKEA, the device aims to analyze raw gas sensor resistance – ohm-level data most devices throw away – combined with temporal spikes, humidity correlations, and a database of 35+ signatures. Of course, there is a lot of work to be done here on the calibration side, and we don’t have any chemical warfare agents on hand to test against, so we have no idea how well it works, and we’d expect false positives. Still, the idea of taking a more granular look at the data coming off the sensor may bear some fruit.

(Editor’s note: edited with a hefty dash of skeptical salt.)

Featured Image by Arjun Lama on Unsplash

Jointly Is A Typeface Designed For CNC Joinery

If you have a CNC router, you know you can engrave just about any text with the right tool, but Jointly is a typeface that isn’t meant to be engraved. That would be too easy for [CobyUnger]. His typeface “Jointly” is the first we’ve seen that’s meant to be used as joinery.

The idea is simple: carve mortises that take the shape of letters in one piece, and carve matching letter-tenons into the end of another. Push them together, and voila: a joint! To get this concept to work reliably, the font did have to be specially designed — both the inner and outer contours need to be accessible to a rotary cutting tool. Cutting tools get harder to use the smaller they go (or more fragile, at any rate) so with Jointly, the design spec was that any letters over 3/4″ (19.05 mm) tall needed to be handled with a 1/8″ (3.175 mm) rotary cutter.

This gives the font a friendly curved appearance we find quite fetching. Of course if you’re going to be cutting tenons into the end of a board, you’re going to need either some serious z-depth or an interesting jig to get the end of the board under the cutting head. It looks like [CobyUnger] has both, but he mentions the possibility of using a handheld CNC router as the cheaper option.

Speaking of routing out type, do you know the story of Gorton? You can’t make joinery with that typeface, but you’ve almost certainly seen it.