Quick 3D-Printed Airfoils With These OpenSCAD Helpers

August 14, 2020 by Elliot Williams 7 Comments

You know how it is. You’re working on a project that needs to move air or water, or move through air or water, but your 3D design chops and/or your aerodynamics knowledge hold you back from doing the right thing? If you use OpenSCAD, you have no excuse for creating unnecessary turbulence: just click on your favorite foil and paste it right in. [Benjamin]’s web-based utility has scraped the fantastic UIUC airfoil database and does the hard work for you.

While he originally wrote the utility to make the blades for a blower for a foundry, he’s also got plans to try out some 3D printed wind turbines, and naturally has a nice collection of turbine airfoils as well.

If your needs aren’t very fancy, and you just want something with less drag, you might also consider [ErroneousBosch]’s very simple airfoil generator, also for OpenSCAD. Making a NACA-profile wing that’s 120 mm wide and 250 mm long is as simple as airfoil_simple_wing([120, 0030], wing_length=250);

If you have more elaborate needs, or want to design the foil yourself, you can always plot out the points, convert it to a DXF and extrude. Indeed, this is what we’d do if we weren’t modelling in OpenSCAD anyway. But who wants to do all that manual labor?

Between open-source simulators, modelling tools, and 3D printable parts, there’s no excuse for sub-par aerodynamics these days. If you’re going to make a wind turbine, do it right! (And sound off on your favorite aerodynamics design tools in the comments. We’re in the market.)

Single Piece 3D-Printed PCB Vise

August 14, 2020 by Danie Conradie 27 Comments

Making full use of the capabilities and advantages of 3D printing requires a very different way of thinking compared to more traditional manufacturing methods. Often we see designs that do not really take these advantages into account, so we’re always on the lookout for interesting designs that embrace the nature of 3D-printed parts in interesting ways. [joopjoop]’s spring-loaded PCB vise is one such ingenious design that incorporates the spring action into the print itself.

This vise is designed to be printed as a single piece, with very little post-processing required if your printer is dialed in. There is a small gap between the base plate and the springs and clamping surfaces that need to be separated with a painters knife or putty knife. Two “handles” have contours for your fingers to operate the clamping surfaces. It opens quickly for inserting your latest custom PCB.

PLA can be surprisingly flexible if the right geometry is used, and these springs are an excellent example of this. In the video below [Chuck Hellebuyck] does a test and review of the design, and it looks like it works well for hand soldering (though it probably won’t hold up well with a hot air station). Last month our own [Tom Nardi] recently reviewed a similar concept that used spiral springs designed into the printed part. While these both get the job done, [Tom’s] overall verdict is that a design like this rubber-band actuated PCB vise is a better long-term option.

It takes some creativity to get right, but printing complete assemblies as a single part, is a very useful feature of 3D printing. Just be careful of trying to make it the solution for every mechanical problem.

Tensile Testing Machine Takes 3D Printed Parts To The Breaking Point

August 13, 2020 by Lewin Day 19 Comments

If you’re serious about engineering the things you build, you need to know the limits of the materials you’re working with. One important way to characterize materials is to test the tensile strength — how much force it takes to pull a sample to the breaking point. Thankfully, with the right hardware, this is easy to measure and [CrazyBlackStone] has built a rig to do just that.

Built on a frame of aluminium extrusion, a set of 3D printed parts to hold everything in place. To apply the load, a stepper motor is used to slowly turn a leadscrew, pulling on the article under test. Tensile forces are measured with a load cell hooked up to an Arduino, which reports the data back to a PC over its USB serial connection.

It’s a straightforward way to build your first tensile tester, and would be perfect for testing 3D printed parts for strength. The STEP files (13.4 MB direct download) for this project are available, but [CrazyBlackStone] recommends waiting for version two which will be published this fall on Thingiverse although we didn’t find a link to that user profile.

Now we’ll be able to measure tensile strength, but the stiffness of parts is also important. You might consider building a rig to test that as well. Video after the break.

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A High Torque Gearbox You Can Print At Home

August 13, 2020 by Lewin Day 10 Comments

Typically, when we think of 3D printed parts, we think of unique parts with complex geometries that would be hard to fabricate with other techniques. Strength is rarely the first thing that comes to mind, due to the limitations of thermoplastics and the problem of delamination between layers. However, with smart design, it’s possible to print parts capable of great feats, just as [Brian]’s high-torque gearbox demonstrates.

Pulling a car is a great way to show off the strength of your build.

The gearbox consists of entirely 3D-printed gears, along with the enclosure, with the only metal parts being a few bearings and shafts. Capable of being produced out of PLA on a regular FDM printer, [Brian] has successfully tested the gearbox up to 132 kg∗cm. The suspicion is that there may be more left in it, but some slippage was noticed in the gear train when trying to tow a Ford Focus with the handbrake still on.

Even better, with the addition of a potentiometer, the gearbox can be used as an incredibly tough servo. [Brian] demonstrates this by lifting 22 kg at a distance of 6 cm from the center of the output shaft. The servo does it with ease, though eventually falls off the bench due to not being held down properly.

It’s a build that shows it’s possible to use 3D-printed parts to do some decently heavy work in the real world, as long as you design appropriately. [Brian] does a great job of explaining what’s involved, discussing gear profile selection and other design choices that affect the final performance. We’ve seen similar work from others before, too. Video after the break.

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3D Printing Interactive Maps For The Visually Impaired

August 11, 2020 by Lewin Day 3 Comments

Most maps and educational materials for teaching geography are highly visual in nature. For those with a visual impairment, it can make learning more difficult when suitable resources are not available. After visiting a boarding school in Moscow, [Sergei] set out to build an interactive map to teach students geography regardless of their vision status.

After seeing the poorly embossed paper maps used in the school, [Sergei] decided there had to be a better way. The solution was 3D printing, which makes producing a map with physical contours easy. Initial attempts involved printing street maps and world maps with raised features, such that students could feel the lines rather than seeing them.

Taking things a step further, [Sergei] went all out, producing an interactive educational device. The build consists of a world map, and contains audio files with information about countries, cultures, and more. When the ultrasonic sensor detects a user in range, it invites them to press or pull out the removable continents on the map. The device can sense touch, thanks to a pair of MPR121 capacitive touch sensor boards which are used to trigger the audio files.

It’s a great way to use the sense of touch to teach where the sense of vision may be lacking. Previous Prize entries have worked in this field too, like this haptic glove to help vision-impaired users interpret camera data. We can’t wait to see what comes next as technology improves!

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

August 11, 2020 by Donald Papp 14 Comments

[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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3D Printable Kinematic Couplings, Ready To Use

August 11, 2020 by Donald Papp 11 Comments

Time may bring change, but kinematic couplings don’t. This handy kinematic couplings resource by [nickw] was for a design contest a few years ago, but what’s great is that it includes ready-to-use models intended for 3D printing, complete with a bill of materials (and McMaster-Carr part numbers) for hardware. The short document is well written and illustrated with assembly diagrams and concise, practical theory. The accompanying 3D models are ready to be copied and pasted anywhere one might find them useful.

What are kinematic couplings? They are a way to ensure that two parts physically connect, detach, and re-connect in a precise and repeatable way. The download has ready-to-use designs for both a Kelvin and Maxwell system kinematic coupling, and a more advanced design for an optomechanical mount like one would find in a laser system.

The download from Pinshape requires a free account, but the models and document are licensed under CC – Attribution and ready to use in designs (so long as the attribution part of the license is satisfied, of course.) Embedded below is a short video demonstrating the coupling using the Maxwell system. The Kelvin system is similar.

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