3D Printing A Lifting Body Aircraft

April 29, 2019 by Lewin Day 17 Comments

When you think of unconventional aircraft, flying wings have had plenty of time in the sun over the last few decades. With striking designs like the B-2 Spirit and F-117A Nighthawk on the flight line, it’s no surprise. The lifting body never really caught on, however, and it languishes in ignominy to this day. Despite their obscurity, [rctestflight] decided to 3D print a few lifting bodies for himself and take them out for a field test (YouTube video, embedded below).

Most aircraft have a body designed with low drag, and wings designed to provide lift. Lifting body aircraft focus the body design on providing that lift and often have no real wing to the design, needing only control surfaces to compliment the body. For this project, several different designs were constructed, with the craft being drop-launched from a multirotor at significant altitude. Initial tests were hamstrung by stability problems, both due to center of gravity issues and uncertain aerodynamic phenomena. The early designs were particularly prone to suddenly entering an unrecoverable flat spin. Later modifications included the addition of further stabilizers, which helped performance somewhat.

3D printing is a great way to experiment with aerodynamic phenomena, as it’s easy to create all manner of complicated geometries to tinker with. [rctestflight] has done solid work developing a basic craft, and we’d love to see the work continue with powered tests and more development. If flying wings are more your jam, though, you can 3D print those too. Video after the break.

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Benchmarking A Garbage Disposal Using The 3DBenchy Tugboat

April 29, 2019 by Ted Yapo 8 Comments

We’ve always had a love-hate relationship with 3DBenchy, the tugboat-shaped 3D printer calibration target. On one hand, it’s incredibly useful to have a common, widely used, and challenging benchmark object to evaluate printer performance and improve tuning, but we’d somehow like to get back the countless frustrated hours we’ve spent trying to get the damn thing perfect with various printers. So, it was with no little joy that we watched the video below by [Eric R Mockler], in which he uses 3DBenchy prints to benchmark his newest acquisition: a new-in-box garbage disposal he scored off Craigslist. Take that, tugboat!

[Eric] is considering using the disposal as the first step in a failed-print-recycling method to ultimately turn the waste back into filament, presumably to print more tugboats. The tiny bits produced by the disposal should provide a reasonable substitute for pelleted plastic feedstock going into a filament extruder, if the disposal is up to the task, that is. Reasoning that any device capable of grinding chicken bones should handle little plastic tugboats just as well, [Eric] gave it shot, and found that the ⅓-horsepower disposal had no problem grinding even 100%-infill PLA prints.

The video is short and to-the-point, so we’ll even excuse the portrait orientation, just this once. If you’re considering recycling your failed prints, too, you’ll also need a filament extruder, and we’ve got you covered with a low-cost version, or a high-throughput one.

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3D Printing With Multiple Soluble Filaments

April 28, 2019 by Tom Nardi 12 Comments

Complex 3D-printed designs often require the use of an automatically generated support structure around them for stability. While this enables some truly incredible results, it adds considerable time and cost to the printing process. Plus there’s the painstaking process of removing all the support material without damaging the object itself. If you’ve got a suitably high-end 3D printer, one solution to this problem is doing the supports in a water soluble filament; just toss the print into a bath and wait for the support to dissolve away.

But what if you’re trying to print something that’s complex and also needs to be soluble? That’s precisely what [Jacob Blitzer] has been experimenting with recently. The trick is finding two filaments that can be printed at the same time but are dissolved with two different solutions. His experimentation has proved it’s possible to do with consumer-level hardware, but it isn’t easy and it’s definitely not cheap.

You might be wondering what the possible application for this technique is. For [Jacob], he wanted to be able to print hollow molds in complex geometric shapes that would ultimately be filled with concrete. The molds required extensive internal supports that would have been all but impossible to remove if they weren’t printed in a soluble filament. But he also wanted to be able to dissolve the mold once the concrete inside had cured. So he needed one easy to dissolve filament for the supports, and a harder to dissolve one for the actual mold.

For the mold itself, [Jacob] went with High Impact Polystyrene (HIPS) which can be dissolved with an industrial degreaser called Limonene. It’s expensive, and rather nasty to work with, but it does an excellent job of eating away the HIPS so that’s one problem solved. Finding a water-soluble filament for the supports that could be printed at similar temperatures to the HIPS took months of research, but eventually he found one called HyroFill that fit the bill. Unfortunately, it costs an eye-watering $175 USD per kilogram.

So you have the filaments, but what can actually print them at the same time? Multi-material 3D printing is a tricky topic, and there’s a few different approaches that have been developed over the years. In the end, [Jacob] opted to go with the FORMBOT T-Rex that uses the old-school method of having two individual hotends and extruders. It’s the simplest method conceptually, but calibrating such a machine is notoriously difficult. Running two exotic and temperamental filaments at the same time certainly doesn’t help matters.

After all the time, money, and effort put into the project (he also had to write the software that would create the 3D models in the first place) [Jacob] says he’s not exactly thrilled with the results. He’s produced some undeniably stunning pieces, but the failure rate is very high. Still, it’s fascinating research that appears to be the first of its kind, so we’re glad that he’s shared it for the benefit of the community and look forward to seeing where it goes from here.

This 3D Scanner Is Your Ticket To Photogrammetry

April 27, 2019 by Brian Benchoff 20 Comments

It seems 3D printers have been around for ages and still we don’t have a good solution for turning physical 3D objects into digital ones. Yes, 3D scanners exist, but the OpenScan is the best 3D scanner we’ve seen. It’s a 3D printed device meant to take pictures of an object that can then be used by photogrammetry software to construct a point cloud. From there, it’s just a matter of messing with meshes to create a 3D printed copy of anything you want.

The latest version of the scanner is an improvement over the previous version that kind of, sort of looked like the Machine from Contact. This was a gigantic hubless ring, with a smartphone attached to the rim. Put an object in the center, and the phone would rotate around the object in every axis, snapping pictures the entire time. Needless to say, a simpler design prevailed. That doesn’t mean the old version didn’t look awesome. The electronics are simply an Arduino clone, two stepper drivers, a character display for control and some headers for connections and power supplies. This is pretty normal stuff for the RepRap crew.

Running this machine is as simple as putting an object in the device and taking a few pictures. There is some support for remotely controlling some cameras, but everything is universal if you have a remote shutter release. This can be plugged into the electronics, and once everything is done you have a few dozen pictures of an object with optimal lighting conditions that can be thrown into your photogrammetry software of choice. (Ed note: at least one that doesn’t rely on the object remaining stationary with respect to the background to estimate camera position.)

Use A 3D Printer To Electrospin Textiles

April 27, 2019 by Jenny List 12 Comments

We are all used to desktop 3D printers that extrude molten plastic in layers to build up finished items. A pair of researchers at the Human-Computer Interaction Institute at Carnegie Mellon University, [Michael Rivera] and [Scott Hudson], have added another capability to their printer: electrospinning of textiles.

Electrospinning is a technique in which an extruded material is accelerated from the extruder by an electrostatic charge to form an extremely thin fibre. By applying a many-kilovolt charge between the extruder and the bed, they can create a fibre and lay it down into a mesh from a height to create a felt-like fabric. The same extruder can also produce conventional solid prints, allowing the creation of composite fabric and solid items. They demonstrate a variety of prints including a folding mobile phone stand, a woven lamp, and an interactive wooly sheep, which along with others can be seen in the video below the break.

The full paper can be downloaded as a PDF, and makes for very interesting reading. The voltages involved mean that your Prusa clone may not have this capability any time soon, but we look forward to the moment when desktop electrospinning is a feature on affordable 3D printers.

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3D Printer Becomes Soldering Robot

April 26, 2019 by Brian Benchoff 48 Comments

What do you do if you have to solder thousands of through-hole parts? The expensive, professional way of doing this is running the boards through a wave soldering machine, or a machine with a fancy CNC solder fountain. The amateur way of soldering thousands of through-hole joints is putting some boards on the workbench and sitting down with a soldering iron. There is nothing in between; you’re either going to go with full automation for a large soldering job, or you’re doing it completely manually. That’s the problem this soldering robot solves. It’s a small, cheap, but still relatively capable soldering robot built out of a 3D printer.

This project is a solution to the development hell of the OpenScan project. This project is built around a small, simple printed circuit board that uses several 0.1″ female headers to connect an Arduino and motor drivers. Soldering them by hand is simply boring, and 3D printers are cheap, so the great mind behind this project decided to use a printer to pump out solder.

The modifications to the printer include a mount for a TS100 soldering iron and a modified filament extruder that pushes a spool of solder through a PTFE tube. The GCode for this soldering job was created manually, but you could also use a slicer instead. After 20 hours of development, the ‘success rate’ – however that is defined – is between 60-80%. That needs to get up to four or five nines before this DIY soldering robot is practical but this is a decidedly not-bad result for a few hours of tinkering.

This printer mod works great for the use case of stuffing a few 0.1″ headers into a board and letting a robot automatically solder the joints, but this printer will run into a problem with the general case of soldering a lot of randomly-shaped through hole parts. You need to actually hold the parts up against the board while soldering. There’s an easy solution to this problem: just flip the 3D printer upside down. This hack of a cheap 3D printer is so, so close to being a great solution to soldering thousands of through-hole parts quickly and easily, and we’re looking forward to seeing where the community takes this idea. You can check out the video demo below.

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This GPS Speedometer Hangs Off Your Handlebars

April 25, 2019 by Brian Benchoff 9 Comments

If you can ride a bike with no handlebars, no handlebars, no handlebars, you can do just about anything. You can take apart a remote control, and you can almost put it back together. You can listen in on a two meter repeater and you can build a GPS module speedometer. That’s what [Jeremy Cook] did with just a few parts, a little 3D design, and some handy zip ties to hold it onto the handlebars, the handlebars.

The electronics for this build are relatively simple, based on an Arduino Pro Mini because that’s just about the smallest readily available development board you’ll be able to find. To this is a LiPo, a LiPo charging circuit, a GPS module, and a single RGB LED. The code gets some data from the GPS module and figures out a speed. This is then translated into a color — red, yellow, or green depending on whether you’re stationary, below 5 km/h, or above 5 km/h.

All these electronics are stuffed into a 3D-printed enclosure. The majority of the enclosure is printed in black, with a translucent top that serves as a great diffuser for the LED. Just two zip ties hold this GPS speedometer onto the handlebars, and from the video below, everything looks great. The GPS module does take some time to get data at first, but that’s a common problem with GPS units that have been powered off for a few days. If only someone made a GPS module that could keep time with no metronome, with no metronome.

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