Print-in-Place Engine Aims To Be The Next Benchy

While there are many in the 3D-printing community who loudly and proudly proclaim never to have stooped to printing a 3DBenchy, there are far more who have turned a new printer loose on the venerable test model, just to see what it can do. But Benchy is getting a little long in the tooth, and with 3D-printers getting better and better, perhaps a better benchmarking model is in order.

Knocking Benchy off its perch is the idea behind this print-in-place engine benchmark, at least according to [SunShine]. And we have to say that he’s come up with an impressive model. It’s a cutaway of a three-cylinder reciprocating engine, complete with crankshaft, connecting rods, pistons, and engine block. It’s designed to print all in one go, with only a little cleanup needed after printing before the model is ready to go. The print-in-place aspect seems to be the main test of a printer — if you can get this engine to actually spin, you’re probably set up pretty well. [SunShine] shares a few tips to get your printer dialed in, and shows a few examples of what can happen when things go wrong. In addition to the complexities of the print-in-place mechanism, the model has a few Easter eggs to really challenge your printer, like the tiny oil channel running the length of the crankshaft.

Whether this model supplants Benchy is up for debate, but even if it doesn’t, it’s still a cool design that would be fun to play with. Either way, as [SunShine] points out, you’ll need a really flat bed to print this one; luckily, he recently came up with a compliant mechanism dial indicator to help with that job.

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Folding Raspberry Pi Enclosure Prints In One Piece, No Screws In Sight

[jcprintnplay] has challenged himself to making Raspberry Pi cases in different ways, and his Fold-a-Pi enclosure tries for a “less is more” approach while also leveraging the strong points of 3D printing. The enclosure prints as a single piece in about 3 hours, and requires no additional hardware whatsoever.

The design requires no screws or other fasteners, and provides a mounting hole for a fan as well as some holes for mounting the enclosure itself to something. All the ports and headers are accessible, and the folding one-piece design is not just a gimmick; in a workshop situation where the Pi needs to be switched out or handled a lot, it takes no time at all to pop the Raspberry Pi in and out of the enclosure.

Microsoft’s 3D Builder has a pretty useful measurement tool for STLs.

[James] points out that the trick with a print-in-place hinge like this is leaving enough space between the parts so that the two pieces aren’t fused together, but not so much space that the print fails. He doesn’t go into detail about how much space worked or didn’t work, but an examination of the downloadable model shows that the clearance used looks like 0.30 mm, intended to be printed with a 0.4 mm nozzle.

[James] also demonstrates the value of being able to do quick iterations on a design when prototyping. In a video (embedded below) The first prototype had the hinge not quite right. In the second prototype there was a lack of clearance when closing. The third one solved both and shows the final design.

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No Assembly Required For This Compliant Mechanism Dial Indicator

If you’ve ever had the good fortune — or, after a shop mishap, the misfortune — to see the insides of a dial indicator, you’ll know the workings of these shop essentials resemble nothing so much as those of a fine Swiss watch. The pinions, gears, and springs within transmit the slightest movement of the instrument’s plunger to a series of dials, making even the tiniest of differences easy to spot.

Not every useful dial indicator needs to have those mechanical guts, nor even a dial for that matter. This compliant mechanism 3D-printed dial-free indicator is perfect for a lot of simple tasks, including the bed leveling chores that [SunShine] designed it for. Rather than print a bunch of gears and assemble them, [SunShine] chose to print the plunger, a fine set of flexible linkage arms, and a long lever arm to act as a needle. The needle is attached to a flexible fulcrum, which is part of the barrel that houses the plunger. Slight movements of the plunger within the barrel push or pull on the needle, amplifying them into an easily read deflection. When attached to the head of a 3D-printer and scanned over the bed, it’s easy to see even the slightest variation in height and make the corresponding adjustments. Check it out in the video below.

We’re big fans of compliant mechanisms, seeing them in everything from robot arms and legs to thrust vectoring for an RC plane. This might look like something from a cereal box, and it certainly doesn’t have the lasting power of a Starrett or Mitutoyo, but then again it costs essentially nothing, and we like that too.

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Printed It: Print-in-Place PCB Gripper

The goal of Printed It is to showcase creations that truly embrace the possibilities offered by desktop 3D printing. The most obvious examples are designs that can be printed quickly and cheaply enough that they’re a valid alternative to commercially available products. But as previous entries into the series have shown, there are also technical considerations. Is it simply a duplicate of something that could be produced via traditional means, or does the design really benefit from the unique nature of 3D printing?

A perfect example is the Print-in-Place PCB Holder/Gripper created by SunShine. This design is able to hold onto PCBs (or really, whatever you wish) without any additional components. Just pull it off the bed, and put it to work. While having to add a rubber band or generic spring would hardly be an inconvenience, there’s always something to be said for a design that’s truly 100% printable.

The secret is the dual flat spiral springs integrated into the device’s jaws. While most of the common thermoplastics used in desktop 3D printing are relatively stiff, the springs have been designed in such a way that they can be printed in standard PLA. The backside of the jaws have teeth that mesh together, so the energy of the springs is combined to provide a clamping force. Serrations have been added to the jaws to catch the edge of the PCB and help stabilize it.

Visually, it’s certainly striking. The design largely eschews right angles, giving it an almost biological appearance. Many have compared it to the head of a mantis, or perhaps some piece of alien technology.

There’s no question that the design leverages the strengths of 3D printing either; there’s no other way to produce its intricate interlocking components, especially without the use of any sort of fasteners. In short, this design is an ideal candidate for Printed It. But there’s still one question to answer: does it actually work?

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Print-in-Place Helping Hand Grabs A Hold Of Your PCB

We probably don’t have to promote the benefits of a third hand or PCB holders in general, such is their obvious utility. While you can arrange some boxes and pile up tools on your bench to get a similar result, a good grip and flexibility to move the PCB around during soldering or performing any other work on it makes life just so much easier. Thanks to 3D printing there have been plenty of inspiring designs that go beyond the usual clumsy-yet-cheap croc clip version of it, and [SunShine] adds one on to the list with his spring-loaded print-in-place PCB gripper, demonstrated in this video and available on Thingiverse.

The gripping part’s design is based on a spring-loaded box [SunShine] created a little while back — which you can read more about in his Instructable. The holder itself comes in two varieties: one that brings its own stand, and one that has a GoPro mount. The first one is really more to show off the design, and while the gripping part is fully functional, it might not perform too well with heavier boards and easily tip over. Sure, a bigger bottom or mounting it to something more sturdy will fix that, but so will the GoPro-mount version, which also adds the whole flexibility aspect.

If you do prefer something standing more sturdily on your desk though, have a look at the concrete-mounted solder squid from earlier this year. And if you’re interested in more of [SunShine]’s work, check out his 3D-printed brush collection.

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Printed It: Hand Cranked Photography Turntable

Even a relatively low-end desktop 3D printer will have no problems running off custom enclosures or parts for your latest project, and for many, that’s more than worth the cost of admission. But if you’re willing to put in the time and effort to become proficient with necessary CAD tools, even a basic 3D printer is capable of producing complex gadgets and mechanisms which would be extremely time consuming or difficult to produce with traditional manufacturing techniques.

Printable bearing cross-section

Once you find yourself at this stage of your 3D printing career, there’s something of a fork in the road. The most common path is to design parts which are printed and then assembled with glue or standard fasteners. This is certainly the easiest way forward, and lets you use printed parts in a way that’s very familiar. It can also be advantageous if you’re looking to meld your own printed parts with existing hardware.

The other option is to fully embrace the unique capabilities of 3D printing. Forget about nuts and bolts, and instead design assemblies which snap-fit together. Start using more organic shapes and curves. Understand that objects are no longer limited to simple solids, and can have their own complex internal geometries. Does a hinge really need to be two separate pieces linked with a pin, or could you achieve the desired action by capturing one printed part inside of another?

If you’re willing to take this path less traveled, you may one day find yourself creating designs such as this fully 3D printed turntable by Brian Brocken. Intended for photographing or 3D scanning small objects without breaking the bank, the design doesn’t use ball bearings, screws, or even glue. Every single component is printed and fits together with either friction or integrated locking features. This is a functional device that can be printed and put to use anywhere, at any time. You could print one of these on the International Space Station and not have to wait on an order from McMaster-Carr to finish it.

With such a clever design, I couldn’t help but take a closer look at how it works, how it prints, and perhaps even some ways it could be adapted or refined going forward.

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3D Printed Buttons, Printed As A Single Unit

These nifty buttons come from [Marc Schömann], and they are intended to cover just about any kind of tact switches. The buttons, their cover, and the compliant bits that act as a spring can be 3D printed as a complete unit that requires no assembly, and can be used fresh off the print bed.

The design is still being developed, but those interested in playing with it can download the current model here. [Marc] printed this version in two colors, but that’s just to make how the buttons work easier to see. It also gave him an opportunity to test and tune the tool changer on his printer.

Tool changer, you say? Yes, indeed. The printer is the Blackbox, a open source, tool-changing 3D printer of [Marc]’s own design with its own Hackaday.io project page.

Embedded below is a video overview of the button design being prepped and printed on a Blackbox printer, with a tool change happening in the process. Tool changing is an attractive feature that many people including E3D have taken a swing at, and it’s always exciting to see it in action.

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