Hackaday Links: April 4, 2021

Can I just say that doing a links roundup article in a week that includes April Fool’s Day isn’t a fun job? Because it’s not. I mean, how can you take something like reports of X-rays flowing from Uranus seriously when they release the report on such a day? It sure looks like a legitimate story, though, and a pretty interesting one. Planets emitting X-rays isn’t really a new thing; we’ve known that Jupiter and Saturn are both powerful X-ray sources for decades. Even though Uranus is the odd child of our solar system, finding evidence for X-ray emissions buried in data captured by the Chandra observatory in 2007 was unexpected. Astronomers think the X-rays might be coming from Uranus’ rings, or they might be reflections of X-rays streaming out from the sun. Or, it might be the weird alignment of the gas giant’s magnetic field causing powerful aurorae that glow in the X-ray part of the spectrum. Whatever it is, it’s weird and beautiful, which all things considered isn’t a bad way for things to be.

Another potential jest-based story popped up this week about the seemingly impossible “EmDrive”. It seems that when you appear to be breaking the laws of physics, you’re probably doing it wrong, and careful lab tests showed that fuel-free propulsion isn’t here yet. One would think it was self-obvious that filling a closed asymmetrical chamber with microwaves would produce absolutely no thrust, but EmDrive proponents have reported small but measurable amounts of thrust from the improbable engine for years. A team at TU Dresden found otherwise, though. Even though they were able to measure a displacement of the engine, it appears to be from the test stand heating up and warping as the RF energy flowed into the drive chamber. By changing the way the engine was supported, they were able to cancel out the dimensional changes that were making it look like the EmDrive was actually working.

Want to use surface-mount parts, but don’t want to bother spinning up an SMD board? Not a problem, at least if you follow the lead of David Buchanan and perform no-surface surface-mount prototyping. We stumbled upon this on Twitter and thought it looked cool — it’s got a little bit of a circuit sculpture feeling, and we like the old-school look of plain 0.1″ perfboard. David reports that the flying leads are just enameled magnet wire; having done our share of scraping and cleaning magnet wire prior to soldering, we figured that part of the build must have been painful. We pinged David and asked if he had any shortcuts for prepping magnet wire, but alas, he says he just used a hot blob of solder and a little patience while the enamel cooked off. We still really like the style of this build, and we applaud the effort.

Speaking of stumbling across things, that’s one of the great joys of this job — falling down algorithmically generated rabbit holes as we troll about for the freshest hacks. One such serendipitous was this YouTube channel documenting a really nice jet engine build. We’ve seen plenty of jet engines before, but very few with afterburners like this one has. There’s also something deeply satisfying about the variable-throat nozzle that Praendy built for the engine — it’s a level of complexity that you don’t often see in hobbyist jet engines, and yet the mechanism is very simple and understandable.

The other rabbit hole we discovered was after reporting on this cool TIG tungsten grinding tool. That took us into The Metalist’s back catalog, where we found a lot of interesting stuff. But the real treat was this automatic tube polisher (video), which we have to say kept us guessing up to the very end. If you’ve got 12 minutes and you enjoy metalworking builds at all, watch it and see if you’re not surprised by the cleverness of this tool.

And finally, we had heard of the travails of Anatoli Bugorski before, but never in the detail presented in this disturbing video. (Embedded below.)

Who is Anatoli Bugorski, you ask? He is a Russian particle physicist who, while working in an accelerator lab in 1978, managed to get his head directly in the path of a 76 GeV proton beam. Despite getting a huge dose of radiation, Bugorski not only survived the accident but managed to finish his Ph.D. and went on to a long career in nuclear physics. He also got married and had a son. He was certainly injured — facial paralysis and partial deafness, mainly — but did not suffer anything like the gruesome fates of the Chernobyl firefighters or others receiving massive radiation doses. The video goes into some detail about how the accident happened — two light bulbs are better than one, it turns out. We enjoyed the video, but couldn’t stop thinking that Bugorski was the Russian atomic-age equivalent of Phineas Gage.

Machinist’s Accuracy Vs. Woodworker’s Precision

There are at least two ways of making parts that fit together exactly. The first way is the Cartesian way, and the machinists way. Imagine that you could specify the size of both the hole and the peg that you’d like to put into it. Just make sure your tolerances are tight enough, and call out a slightly wider hole. Heck, you can look up the type of fit you’d like in a table, and just specify that. The rest is a simple matter of machining the parts accurately to the right tolerances, and you’re done.

The machinist’s approach lives and dies on that last step — making the parts accurately fit the measure. Contrast the traditional woodworker’s method, or at least as it was taught to me, of just making the parts fit each other in the first place. This is the empirical way, the Aristotelian way if you will. You don’t really have to care if the two parts are exactly 30.000 mm wide, as long as they’re precisely the same length. And woodworkers have all sorts of clever tricks to make things the same, or make them fit, without measuring at all. Their methods are heavy on the jigs and the clever set-ups, and extraordinarily light on the calipers. To me, coming from a “measure carefully, and cut everything to measure” background, these ways of working were a revelation.

This ends up expressing perfectly the distinction between accuracy and precision. Sometimes you need to hit the numbers right on, and other times, you just need to get the parts to fit. And it’s useful to know which of these situations you’re actually in.

Of course, none of this is exclusive to metal or wood, and I’m actually mentioning it because I find myself using ideas that I learned in one context and applying them in the other. For instance, if you need sets of holes that match each other perfectly, whether in metal or wood, you get that precision for free by drilling through two sheets at one time, or by making a template — no measuring needed. Instead of measuring an exact distance from a feature, if all you care about is two offsets being the same, you can find a block of scrap with just about the right width, and use that to mark both distances. Is it exactly 1.000″ wide? Nope. But can you use this to mark identical locations? Yup.

You can make surprisingly round objects in wood by starting with a square, and then precisely marking the centers of the straight faces, and then cutting off the corners to get an octagon. Repeat with the centers and cutting until you can’t see the facets any more. Then hit it with sandpaper and you’re set. While this won’t make as controlled a diameter as would come off a metal lathe, you’d be surprised how well this works for making round sheet-aluminum circles when you don’t care so much about the diameter. And the file is really nothing other than the machinist’s sandpaper (or chisel?).

I’m not advocating one way of working over the other, but recognizing that there are two mindsets, and taking advantage of both. There’s a certain freedom that comes from the machinist’s method: if both parts are exactly 25.4 mm long, they’re both an accurate inch, and they’ll match each other. But if all you care about is precise matching, put them in the vise and cut them at the same time. Why do you bother with the calipers at all? Cut out the middle-man!

3D-Printed Press-Forming Tools Dos And Don’ts

Press-forming is a versatile metal forming technique that can quickly and easily turn sheet metal into finished parts. But there’s a lot of time and money tied up in the tooling needed, which can make it hard for the home-gamer to get into. Unless you 3D-print your press-form tooling, of course.

Observant readers will no doubt recall our previous coverage of press-forming attempts with plastic tooling, which were met with varying degrees of success. But [Dave]’s effort stands apart for a number of reasons, not least of which is his relative newbishness when it comes to hot-squirt manufacturing. Even so, he still came up with an interesting gradient infill technique that put most of the plastic at the working face of the dies. That kept print times in the reasonable range, at least compared to the days of printing that would have been needed for 100% infill through the whole tool profile.

The other innovation that we liked was the idea to use epoxy resin to reinforce the tools. Filling the infill spaces on the tools’ undersides with resin resulted in a solid, strong block that was better able to withstand pressing forces. [Dave] didn’t fully account for the exothermic natures of the polymerization reaction, though, and slightly warped the tools. But as the video below shows, even suboptimal tools can perform, bending everything he threw at them, including the hydraulic press to some extent.

It sure seems like this is one technique to keep in mind for a rainy day. And hats off to [Dave] for sharing what didn’t work, since it points the way to improvements.

Continue reading “3D-Printed Press-Forming Tools Dos And Don’ts”

Scratch-Built Rolling Tool Cabinet Is A Metalworking Skill-Builder

Yes, rolling tool cabinets in every conceivable shape, size, arrangement of drawers, and even color are readily available commercially, and you probably shouldn’t build your own. But as [Bob] from “Making Stuff” points out, where’s the fun in that?

Still, we can think of plenty of reasons to make your own rolling tool cabinets from scratch. Aside from the obvious benefits of practicing your metalworking skills and putting your tools to good use, rolling your own means you can get exactly what you want. Almost every tool cabinet we’ve purchased has ended up being just a bit sub-optimal in some way — too wide for the available space, or perhaps with drawers a touch too shallow to fit that one oddball tool. Being able to create your own cabinet means you can hit the specs exactly, and as [Bob] shows, it’s not even that hard if you have the right tools.

The build starts on [Bob]’s CNC plasma cutter, a shop-built machine that’s seen several upgrades over the years. The plasma cutter makes quick work of cutting the drawer blanks from sheet steel, complete with slots to make forming the sheets into drawers easy. The frame of the cabinet is steel tubing, which is welded up and filled in with more sheet steel. Full-extension ball-bearing slides are added to the sides to support the drawers; we have to admit that welding what appears to be zinc-coated steel makes us nervous, but we assume [Bob] took precautions against the potential for toxic fumes.

The video below shows the whole build process and shows off the very sharp-looking final product. It also puts us very much in the mood to build our own plasma cutter.

Continue reading “Scratch-Built Rolling Tool Cabinet Is A Metalworking Skill-Builder”

Machining A Honing Jig Will Keep Skills Sharp

[Amy Makes Stuff] has long used a pair of diamond honing blocks to freehand sharpen planes, chisels, and all the other dull things around the shop. Although this method works fairly well, the results are often inconsistent without some kind of jig to hold the blade securely as it’s being sharpened. These types of devices are abundant and cheap to buy, but as [Amy] says in the video after the break, then she doesn’t get to machine anything. Boy, do we know that feeling.

[Amy] was able to make this completely out of stuff she had lying around, starting with a block of scrap aluminium that eventually gets cut into the two halves of the jig. The video is full of tips and tricks and it’s really interesting to see [Amy]’s processes up close. Our favorite part has to be that grippy knob that expands and contracts the jig. [Amy] made it by drilling a bunch of holes close to the outside edge of a circle, and then milled away the edge until she had a fully fluted knob. Once she had the jig finished, she upgraded her honing blocks by milling a new home for them out of milky-white high-density polyethylene.

Mills are fantastic tools to have, but they’re a bit on the pricey side. If you’re just getting started, why not convert a drill press into a mill? Wouldn’t that be more fun that just buying one?

Continue reading “Machining A Honing Jig Will Keep Skills Sharp”

A Motorized Rotary Shop Table From Scratch

As we’ve seen over the years, it’s possible to bootstrap your own metalworking shop using little more than a pile of scrap steel, a welder, and an angle grinder. With time and dedication, you can build increasingly complex shop tools until you’ve got yourself a nice little post-apocalyptic workshop. It’s the whole idea behind the [Workshop From Scratch] channel, and we never get bored of seeing his incredible backyard engineering.

But eventually, you’ll have built all the basic stuff. What then? Well, as [Workshop From Scratch] shows in a recent video, you can start working on the luxuries. Do you need a motorized table that will let you spin the workpiece and position it an at arbitrary angle? No, probably not. But as the video after the break shows, it’s certainly a handy thing to have around the shop. We especially like how he uses it to quickly and easily produce nearly perfect circular welds.

Note the welded standoffs used to hold on the lid.

From a technical standpoint, this is perhaps one of his more straightforward builds. But at the same time, the attention to detail that he puts into even this “simple” design is phenomenal. Nothing is wasted, and cutoff pieces from one section are often used in imaginative ways elsewhere.

[Workshop From Scratch] is truly a master of working with what you have, and this project is a perfect example. We especially like the tilt mechanism, which uses a massive leadscrew spun by a wiper motor salvaged from an Audi A8 B4. It looks like a fair amount of new hardware went into the control electronics, but even still, we have no doubt that the cost of this build is well below the purchase price of a commercial alternative.

Much like his hydraulic lifting table or motorized plasma cutter, not everyone is going to need something this elaborate in their home shop. But his magnetic vise and mobile drill press cart are far more approachable for the home gamer. Of course even if you don’t follow along and build your own versions of his tools, it’s always worth tuning in just to see him work.

Continue reading “A Motorized Rotary Shop Table From Scratch”

Building A Scooter Exhaust From Scrap Metal

When a part on a vehicle fails, oftentimes the response is to fit a new one fresh out the box. However, sometimes, whether by necessity or simply for the love of it, it’s possible to handcraft a solution instead. [Samodel] does just that when whipping up a new exhaust for his scooter out of scrap metal.

It’s a great example of classic backyard metalworking techniques. The flange is recreated using a cardboard template rubbed on the exhaust port, with the residual oil leaving a clear impression. Hard work with a grinder and drill get things started, with an insane amount of filing to finish the piece off nicely. A properly tuned pipe is then sketched out on the computer, and a paper template created. These templates are cut out of an old fridge to create the main muffler section.

There’s plenty of other hacks, too – from quick and dirty pipe bends to handy sheet forming techniques. It’s not the first time we’ve seen great metalworking with scrap material, either. Video after the break.

[Thanks to BrendaEM for the tip]

Continue reading “Building A Scooter Exhaust From Scrap Metal”