A Brand-New Additive PCB Fab Technique?

October 27, 2024 by Dan Maloney 68 Comments

Usually when we present a project on these pages, it’s pretty cut and dried — here’s what was done, these are the technologies used, this was the result. But sometimes we run across projects that raise far more questions than they answer, such as with this printed circuit board that’s actually printed rather than made using any of the traditional methods.

Right up front we’ll admit that this video from [Bad Obsession Motorsport] is long, and what’s more, it’s part of a lengthy series of videos that document the restoration of an Austin Mini GT-Four. We haven’t watched the entire video much less any of the others in the series, so jumping into this in the middle bears some risk. We gather that the instrument cluster in the car is in need of a tune-up, prompting our users to build a PCB to hold all the instruments and indicators. Normally that’s pretty standard stuff, but jumping to the 14:00 minute mark on the video, you’ll see that these blokes took the long way around.

Starting with a naked sheet of FR4 substrate, they drilled out all the holes needed for their PCB layout. Most of these holes were filled with rivets of various sizes, some to accept through-hole leads, others to act as vias to the other side of the board. Fine traces of solder were then applied to the FR4 using a modified CNC mill with the hot-end and extruder of a 3D printer added to the quill. Components were soldered to the board in more or less the typical fashion.

It looks like a brilliant piece of work, but it leaves us with a few questions. We wonder about the mechanics of this; how is the solder adhering to the FR4 well enough to be stable? Especially in a high-vibration environment like a car, it seems like the traces would peel right off the board. Indeed, at one point (27:40) they easily peel the traces back to solder in some SMD LEDs.

Also, how do you solder to solder? They seem to be using a low-temp solder and a higher temperature solder, and getting right in between the melting points. We’re used to seeing solder wet into the copper traces and flow until the joint is complete, but in our experience, without the capillary action of the copper, the surface tension of the molten solder would just form a big blob. They do mention a special “no-flux 96S solder” at 24:20; could that be the secret?

We love the idea of additive PCB manufacturing, and the process is very satisfying to watch. But we’re begging for more detail. Let us know what you think, and if you know anything more about this process, in the comments below.

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Retrotechtacular: Making Enough Merlins To Win A War

October 25, 2024 by Dan Maloney 16 Comments

From the earliest days of warfare, it’s never been enough to be able to build a deadlier weapon than your enemy can. Making a sharper spear, an arrow that flies farther and straighter, or a more accurate rifle are all important, but if you can’t make a lot of those spears, arrows, or guns, their quality doesn’t matter. As the saying goes, quantity has a quality of its own.

That was the problem faced by Britain in the run-up to World War II. In the 1930s, Rolls-Royce had developed one of the finest pieces of engineering ever conceived: the Merlin engine. Planners knew they had something special in the supercharged V-12 engine, which would go on to power fighters such as the Supermarine Spitfire, and bombers like the Avro Lancaster and Hawker Hurricane. But, the engine would be needed in such numbers that an entire system would need to be built to produce enough of them to make a difference.

“Contribution to Victory,” a film that appears to date from the early 1950s, documents the expansive efforts of the Rolls-Royce corporation to ramp up Merlin engine production for World War II. Compiled from footage shot during the mid to late 1930s, the film details not just the exquisite mechanical engineering of the Merlin but how a web of enterprises was brought together under one vast, vertically integrated umbrella. Designing the engine and the infrastructure to produce it in massive numbers took place in parallel, which must have represented a huge gamble for Rolls-Royce and the Air Ministry. To manage that risk, Rolls-Royce designers made wooden scale models on the Merlin, to test fitment and look for potential interference problems before any castings were made or metal was cut. They also set up an experimental shop dedicated to looking at the processes of making each part, and how human factors could be streamlined to make it easier to manufacture the engines.

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Simple PCB Repairs Keep Old Vehicle Out Of The Crusher

October 24, 2024 by Dan Maloney 21 Comments

For those of us devoted to keeping an older vehicle on the road, the struggle is real. We know that at some point, a part will go bad and we’ll learn that it’s no longer available from the dealer or in the aftermarket, at least at a reasonable cost. We might get lucky and find a replacement at the boneyard, but if not — well, it was nice knowing ya, faithful chariot.

It doesn’t have to be that way, though, at least if the wonky part is one of the many computer modules found in most cars made in the last few decades. Sometimes they can be repaired, as with this engine control module from a Ford F350 pickup. Admittedly, [jeffescortlx] got pretty lucky with this module, which with its trio of obviously defective electrolytics practically diagnosed itself. He also had the advantage of the module’s mid-90s technology, which still relied heavily on through-hole parts, making the repair easier.

Unfortunately, his luck stopped there, as the caps had released the schmoo and corroded quite a few traces on the PCB. Complicating the repair was the conformal coating on everything, a common problem on any electronics used in rough environments. It took a bit of probing and poking to locate all the open traces, which included a mystery trace far away from any of the leaky caps. Magnet wire was used to repair the damaged traces, the caps were replaced with new ones, and everything got a fresh coat of brush-on conformal coating.

Simple though they may be, we really enjoy these successful vehicle module repairs because they give us hope that when the day eventually comes, we’ll stand a chance of being able to perform some repair heroics. And it’s nice to know that something as simple as fixing a dead dashboard cluster can keep a car out of the crusher.

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3D Printed Tires, By The Numbers

October 24, 2024 by Dan Maloney 21 Comments

What does it take to make decent tires for your projects? According to this 3D printed tire torture test, it’s actually pretty easy — it’s more a question of how well they work when you’re done.

For the test, [Excessive Overkill] made four different sets of shoes for his RC test vehicle. First up was a plain PLA wheel with a knobby tread, followed by an exact copy printed in ABS which he intended to coat with Flex Seal — yes, that Flex Seal. The idea here was to see how well the spray-on rubber compound would improve the performance of the wheel; ABS was used in the hopes that the Flex Seal solvents would partially dissolve the plastic and form a better bond. The next test subjects were a PLA wheel with a separately printed TPU tire, and a urethane tire molded directly to a PLA rim. That last one required a pretty complicated five-piece mold and some specialized urethane resin, but the results looked fantastic.

Non-destructive tests on the tires included an assessment of static friction by measuring the torque needed to start the tire rolling against a rough surface, plus a dynamic friction test using the same setup but measuring torque against increasing motor speed. [Overkill] threw in a destructive test, too, with the test specimens grinding against a concrete block at a constant speed to see how long the tire lasted. Finally, there was a road test, with a full set of each tire mounted to an RC car and subjected to timed laps along a course with mixed surfaces.

Results were mixed, and we won’t spoil the surprise, but suffice it to say that molding your own tires might not be worth the effort, and that Flex Seal is as disappointing as any other infomercial product. We’ve seen other printed tires before, but hats off to [Excessive Overkill] for diving into the data.

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A Wobble Disk Air Motor With One Moving Part

October 22, 2024 by Dan Maloney 17 Comments

In general, the simpler a thing is, the better. That doesn’t appear to apply to engines, though, at least not how we’ve been building them. Pistons, cranks, valves, and seals, all operating in a synchronized mechanical ballet to extract useful work out of some fossilized plankton.

It doesn’t have to be that way, though, if the clever engineering behind this wobbling disk air engine is any indication. [Retsetman] built the engine as a proof-of-concept, and the design seems well suited to 3D printing. The driven element of the engine is a disk attached to the equator of a sphere — think of a model of Saturn — with a shaft running through its axis. The shaft is tilted from the vertical by 20° and attached to arms at the top and bottom, forming a Z shape. The whole assembly lives inside a block with intake and exhaust ports. In operation, compressed air enters the block and pushes down on the upper surface of the disk. This rotates the disc and shaft until the disc moves above the inlet port, at which point the compressed air pushes on the underside of the disc to continue rotation.

[Resetman] went through several iterations before getting everything to work. The main problems were getting proper seals between the disc and the block, and overcoming the friction of all-plastic construction. In addition to the FDM block he also had one printed from clear resin; as you can see in the video below, this gives a nice look at the engine’s innards in motion. We’d imagine a version made from aluminum or steel would work even better.

If [Resetman]’s style seems familiar, it’s with good reason. We’ve featured plenty of his clever mechanisms, like this pericyclic gearbox and his toothless magnetic gearboxes.

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Hackaday Links: October 20, 2024

October 20, 2024 by Dan Maloney 44 Comments

When all else fails, there’s radio. Hurricane Helene’s path of destruction through Appalachia stripped away every shred of modern infrastructure in some areas, leaving millions of residents with no ability to reach out to family members or call for assistance, and depriving them of any news from the outside world. But radio seems to be carrying the day, with amateur radio operators and commercial broadcasters alike stepping up to the challenge.

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DIY Air Bearings, No Machining Required

October 20, 2024 by Dan Maloney 26 Comments

Seeing a heavy load slide around on nearly frictionless air bearings is pretty cool; it’s a little like how the puck levitates on an air hockey table. Commercial air bearings are available, of course, but when you can build these open-source air bearings, why bother buying?

One of the nice things about [Diffraction Limited]’s design is that these bearings can be built using only simple tools. No machining is needed past what can be easily accomplished with a hand drill, thanks to some clever 3D-printed jigs that allow you to drill holes with precision into stainless steel discs you can buy on the cheap. An extremely flat surface is added to the underside of these discs thanks to another jig, some JB Weld epoxy, and a sheet of float glass to serve as an ultra-flat reference. Yet more jigs make it easy to scribe air channels into the flat surface and connect them to the air holes through a bit of plaster of Paris, which acts as a flow restriction. The video below shows the whole process and a demo of the bearings in action.

[Diffraction Limited] mentions a few applications for these air bearings, but the one that interests us most is their potential use in linear bearings; a big CNC cutter using these air bearings would be pretty cool. We seen similar budget-friendly DIY air bearings before, including a set made from used graphite EDM electrodes.

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