When Stirling Engines Meet 3D Printers

Let’s face it, everybody wants to build a Stirling engine. They’re refined, and generally awesome. They’re also a rather involved fabrication project which is why you don’t see a lot of them around.

This doesn’t remove all of the complexity, but by following this example 3D printing a Sterling engine is just about half possible. This one uses 3D printing for the frame, mounting brackets, and flywheel. That wheel gets most of its mass from a set of metal nuts placed around the wheel. This simple proof-of-concept using a candle is shown off in the video after the break, where it also gets an upgrade to an integrated butane flame.

Stirling engines operate on heat, making printed plastic parts a no-go for some aspects of the build. But the non-printed parts in this design are some of the simplest we’ve seen, comprising a glass syringe, a glass cylinder, and silicone tubing to connect them both. The push-pull of the cylinder and syringe are alternating movements caused by heat of air from a candle flame, and natural cooling of the air as it moves away via the tubing.

We’d say this one falls just above mid-way on the excellence scale of these engines (and that’s great considering how approachable it is). On the elite side of things, here’s a 16-cylinder work of art. The other end of the scale may not look as beautiful, but there’s nothing that puts a bigger smile on our faces than clever builds using nothing but junk.

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Hybrid 3D-Printer Creates Complete Circuits, Case and All

The cool kids these days all seem to think we’re on the verge of an AI apocalypse, at least judging by all the virtual ink expended on various theories. But our putative AI overlords will have a hard time taking over the world without being able to build robotic legions to impose their will. That’s why this advance in 3D printing that can incorporate electronic circuits may be a little terrifying, at least to some.

The basic idea that [Florens Wasserfall] and colleagues at the University of Hamburg have come up with is a 3D-printer with a few special modifications. One is a separate extruder than squirts a conductive silver-polymer ink, the other is a simple vacuum tip on the printer extruder for pick and place operations. The bed of the printer also has a tray for storing SMD parts and cameras for the pick-and-place to locate parts and orient them before placing them into the uncured conductive ink traces.

The key to making the hardware work together though is a toolchain that allows circuits to be integrated into the print. It starts with a schematic in Eagle, which joins with the CAD model of the part to be printed in a modified version of Slic3r, the open-source slicing package. Locations for SMD components are defined, traces are routed, and the hybrid printer builds the whole assembly at once. The video below shows it in action, and we’ve got to say it’s pretty slick.

Sure, it’s all academic for now, with simple blinky light circuits and the like. But team this up with something like these PCB motors, and you’ve got the makings of a robotic nightmare. Or not.

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PCB Production on the Sienci Mill One

A complete start to finish electronics prototyping workshop is nirvana for many of us: being able to go from design on the computer to real hardware without having to get up from your rolling chair. The falling prices of 3D printers have helped make at least part of this a reality: $200 USD is enough to get you a printer that can churn out decent looking enclosures. But there’s more to producing your own hardware than creating slick looking project boxes; at some point you’ll need to put some electronics in there.

For [Chuck Hellebuyck] at least, the last piece of the puzzle has just fallen into place. He’s recently put up a YouTube video describing how he converted his $399 Sienci Mill One into a capable PCB mill. With a 3D printer and this new PCB mill, he’s happy to say he can now go from concept to production all on the same workbench.

The Sienci Mill One is a solid enough mill in its own right but did need some modification to attain the accuracy necessary for cutting at a depth of only .9 mm. First, a block of wood was cut to the same size as the original plastic bed of the Sienci, and then the mill itself was used to drill holes through the wood block and plastic bed. The wood was attached to the bed using a nut and bolt in each corner, being sure to torque it down enough that the head of the bolt is pulled down flush with the surface of the wood.

Pulling the head of the bolts flush wasn’t just to keep the surface free of any snags, [Chuck] uses them in conjunction with a probe in the mill’s chuck as a simple way of adjusting the Z height. With a continuity meter attached between the two, he could lower the probe down until they were touching just enough to make a circuit.

Click through the break for the rest of the story!

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Drill the Wet Side Wet and the Dry Side Dry

Working mostly in metal as he does, [Tuomas Soikkeli] has invested in some nice tools. So when his sweet magnetic-base drill was in need of a new home, he built this two-in-one drilling station to maximize shop space and add some versatility to boot.

For the non-metalworkers out there, a mag-base drill is basically a portable drill press where the base is replaced with a strong electromagnet like the one shown here. They’re often used in the construction trades to drill holes in steel beams or columns, and often include nice features like a built-in coolant system.

[Tuomas] effectively turned his mag-base drill into a very beefy drill press by mounting it to a disused miter saw stand. A thick piece of plate steel forms the base, and with holes and drain channels machined into it, used coolant can be captured in a drain pan below for reuse. A second base for a benchtop drill press means he’s got a dry drilling station too, and the original support arms on the miter stand are ready for drilling long stock. The drawer below the dry side is a nice touch too.

There’s a lot to learn about fabrication from [Tuomas]’ video and the others on his channel, which is well worth checking out. And if you want to convert your drill press into a mag-base drill, why not check out this microwave oven transformer to electromagnetic crane project for inspiration?

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Shop-Made Fixture Turns Out Dream Welds

You can tell a lot about a person by the company they keep, and you can tell a lot about a craftsman by the tools and jigs he or she builds. Whether for one-off jobs or long-term use, these ad hoc tools, like this tubing rotator for a welding shop, help deliver results beyond the ordinary.

What we appreciate about [Delrin]’s tool is not how complex it is — with just a motor from an old satellite dish and a couple of scooter wheels, it’s anything but complicated. What we like is that to fabricate some steering links, each of which required three passes of TIG welding to attach a threaded bung to the end of a rod, [Delrin] took the time to build just the tool for the job. The tools slowly rotates the rod, letting the welder keep the torch in one position as the workpiece moves under it. The grounding method is also simple but clever — just a wide strap of braid draped over the rod. The result is some of the prettiest and most consistent welds we’ve seen in a while, and with an order for 28 steering links, it ought to be a huge time saver.

It may be time for a little more TIG welding love around here. Sure, we’ve covered the basics of oxy-acetylene welding, and even talked about brazing aluminum. Perhaps your humble Hackaday writer will take the plunge into a new TIG welder and report from a newbie’s perspective. You know, for science.

[via r/welding]

The Narrowing Gap Between Amateur and Professional Fabrication

The other day I saw a plastic part that was so beautiful that I had to look twice to realize it hadn’t been cast — and no, it didn’t come out of a Stratysys or anything, just a 3D printer that probably cost $1,500. It struck me that someone who had paid an artisan to make a mold and cast that part might end up spending the same amount as that 3D printer. It also struck me that the little guys are starting to catch up with the big guys.

Haz Bridgeport, Will Mill

Sometimes it’s just a matter of getting a hold of the equipment. If you need a Bridgeport mill for your project, and you don’t have one, you have to pay for someone else to make the thing — no matter how simple. You’re paying for the operator’s education and expertise, as well as helping pay for the maintenance and support of the hardware and the shop it’s housed in.

I once worked in a packaging shop, and around 2004 we got in a prototype to use in developing the product box. This prototype was 3D printed and I was told it cost $12,000 to make. For the era it was mind blowing. The part itself was simplistic and few folks on Thingiverse circa 2017 would be impressed; the print quality was roughly on par with a Makerbot Cupcake. But because the company didn’t have a 3D printer, they had to pay someone who owned one a ton of cash to make the thing they wanted.

Unparalleled Access to Formerly Professional-Only Tools

But access to high end tools has never been easier. Hackerspaces and tool libraries alone have revolutionized what it means to have access to those machines. There are four or five Bridgeports (or similar vertical mills) at my hackerspace and I believe they were all donated. For the cost of membership, plus the time to get trained in and checked out, you can mill that part for cheap. Repeat with above-average 3D printers, CNC mills, vinyl cutters, lasers. The space’s South Bend lathe (pictured) is another example of the stuff most people don’t have in their basement shops. This group ownership model may not necessarily grant you the same gear as the pros, but sometimes it’s pretty close.
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So, You’ve Never Made A Spaceframe Before

It is sometimes a surprise in our community of tinkerers, builders, hackers, and makers, to find that there are other communities doing very similar things to us within their own confines, but in isolation to ours. A good example are the modified vehicle crowd. In their world there are some epic build stories and the skills and tools they take for granted would not in any way be unfamiliar to most Hackaday readers.

As part of a discussion about electric vehicles near where this is being written, someone tossed an interesting link from that quarter into the mix; a two-part treatise on building ultra-light-weight tubular frame vehicles. Or space frames, as you might know them.

You might think that making a tubular framed for a vehicle would be a straightforward enough process, but as the article explains, it contains within it a huge well of geometry and metallurgy to avoid a creation that is neither too heavy nor contains excessive weakness. Part one deals mainly with prototyping a frame, the selection of materials and joining tubes, while part two goes into more detail on fabrication. The author likes brazing which may offend the sensibilities of welding enthusiasts, but you can substitute your jointing tech of choice.

A particularly neat suggestion, one of those simple ideas that make you wish you’d thought of it yourself, is to prototype a frame in miniature with copper wire and solder to evaluate the effect of different forces upon it before you commit your final design to steel.

The articles are a few years old, but no less pertinent in the information they contain. Meanwhile if you are a spaceframe veteran, then you may have your own suggestions for the comments below. And if you’d like some tips on how not to build a spaceframe, have a look at this motorcycle.

Thank you [JHR] and [Jarkman] for the tips.