Print Your Own Filament

June 2, 2018 by Al Williams 25 Comments

Ask anyone with a 3D printer what they make the most. They’ll probably say “trash.” There are extra pieces, stuff that oozes out of the extruder, support material, parts that didn’t stick to the bed, or just parts that needed a little tweaking to get right. No matter what you do, you are going to wind up with a lot of scraps. It would be great if you could recycle all this, and [3D Printing Nerd] looks at the FelFil Evo Filament extruder that promises it can do just that. You can see the video below.

As you’d expect, the device is a motorized auger that extrudes filament through a hot end not dissimilar to your printer’s hot end. You have to run a bag of special material through it first to clean out the plastic path. After that, you can create filament from standard pellets or pieces of old plastic.

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Prestretched Fabric Prints Pop Into The Third Dimension

June 1, 2018 by Sonya Vasquez 17 Comments

Printing on fabric might be a familiar trick, but adding stretch into the equation gives our fabric prints the ability to reconstitute themselves back into 3D. That’s exactly what [Gabe] has accomplished; he’s developed a script that takes open 3d meshes and converts them to a hexagonal pattern that, when 3D-printed on a stretched fabric, lets them pop into 3D upon relaxing the fabric.

[Gabe’s] algorithm first runs an open 3D surface through the “Boundary-First Flattening Algorithm,” which gives [Gabe] a 2D mesh of triangles. Triangles are then mapped to hexagons based on size, which produces a landscape of 2D hexagons. Simply printing this hexagonal pattern onto prestretched fabric defines the shape of the object that will surface when the fabric is allowed to relax. As for how to wrap our heads around the mapping algorithm, as [Gabe] explains it, “The areas that experienced the most shrinkage in the flattening process should experience the least shrinkage when the fabric contracts after printing, and the regions that experienced little to no shrinkage in the flattening process should contract as much as possible in the fabric representation.”

If that seems tricky to visualize, just imagine taking a cheap halloween mask and trying to crush it flat onto a table. To smush it perfectly flat, some sections need to stretch while others need to shrink. Once flat though, we can simply keep stretching to remove all the sections that needed to shrink. At this point, if our material were extremely elastic, we could simply let go and watch our rubber mask jump back into 3D. That’s the secret behind [Gabe’s] hexagonal pattern. The size and spacing of these hexagons limit the degree to which local regions of the fabric are allowed to contract. In our rubber mask example, the sections that we stretched out the furthest have the most to travel, so they should contract as much as possible, while the sections that shrank in the initial flattening (although we kept stretching until they too needed to stretch) should shrink the least.

We’ve seen some classy fabric-printing tricks in the past. If you’re hungry for more 3D printing on fabric, have a look at [David Shorey’s] flexible fabric designs.

Thanks for the tip, [Amy]!

The Solid State Weather Station

May 17, 2018 by Anool Mahidharia 60 Comments

Building personal weather stations has become easier now than ever before, thanks to all the improvements in sensors, electronics, and prototyping techniques. The availability of cheap networking modules allows us to make sure these IoT devices can transmit their information to public databases, thereby providing local communities with relevant weather data about their immediate surroundings.

[Manolis Nikiforakis] is attempting to build the Weather Pyramid — a completely solid-state, maintenance free, energy and communications autonomous weather sensing device, designed for mass scale deployment. Typically, a weather station has sensors for measuring temperature, pressure, humidity, wind speed and rainfall. While most of these parameters can be measured using solid-state sensors, getting wind speed, wind direction and rainfall numbers usually require some form of electro-mechanical devices.

The construction of such sensors is tricky and non-trivial. When planning to deploy in large numbers, you also need to ensure they are low-cost, easy to install and don’t require frequent maintenance. Eliminating all of these problems could result in more reliable, low-cost weather stations to be built, which can then be installed in large numbers at remote locations.

[Manolis] has some ideas on how he can solve these problems. For wind speed and direction, he plans to obtain readings from the accelerometer, gyroscope, and compass in an inertial sensor (IMU), possibly the MPU-9150. The plan is to track the motion of the IMU sensor as it swings freely from a tether like a pendulum. He has done some paper-napkin calculations and he seems confident that it will provide the desired results when he tests his prototype. Rainfall measurement will be done via capacitive sensing, using either a dedicated sensor such as the MPR121 or the built-in touch capability in the ESP32. The design and arrangement of the electrode tracks will be important to measure the rainfall correctly by sensing the drops. The size, shape and weight distribution of the enclosure where the sensors will be installed is going to be critical too since it will impact the range, resolution, and accuracy of the instrument. [Manolis] is working on several design ideas that he intends to try out before deciding if the whole weather station will be inside the swinging enclosure, or just the sensors.

If you have any feedback to offer before he proceeds further, let him know via the comments below.

3D Printering: When An STL File Is Not Quite Right

May 16, 2018 by Donald Papp 49 Comments

STL files are everywhere. When there’s something to 3D print, it’s probably going to be an STL. Which, as long as the model is good just as it is, is no trouble at all. But sooner or later there will be a model that isn’t quite right in some way and suddenly project progress hits a snag.

When models interface with other physical things, those other components may not always be exactly as the designer expected. Being mindful about such potential inconsistencies during the design phase can help prevent problems, but it’s not always avoidable. The reason it’s a problem is because an STL file represents a solid model as a finished unit; it is not really intended to be rolled back into CAD programs for additional design changes.

STL files can be edited, but just like re-modeling a component from scratch, it can be a tricky process for those who don’t live and breathe this stuff. I’ll describe a few common issues related to STLs that can hold up getting that new project together, along with ways to deal with them. Thanks to 3D printing becoming much more commonplace, basic tools are within reach of even the least CAD-aware among us.

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3D Printing Air Quality Study

May 13, 2018 by Al Williams 18 Comments

You’ll often hear about some study in the media and then — on examination — find it doesn’t really apply to your situation. Sure, substance X causes cancer in rats, but they ate 8 pounds of it a day for a decade. That’s why we were glad to see [Chuck] post a series of videos about 3D printing air quality based on his practical experience. You can see the summary video, below.

[Chuck] is quick to point out that he isn’t a doctor or even a chemist. He also admits the $100 meter from IGERESS he is using isn’t necessarily high-quality test gear. Still, the data is a good guideline and he did get repeatable results.

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Fail Of The Week: 3D Printed Worm Gear Drive Project Unveils Invisible Flaw

May 11, 2018 by Roger Cheng 27 Comments

All of us would love to bring our projects to life while spending less money doing so. Sometimes our bargain hunting pays off, sometimes not. Many of us would just shrug at a failure and move on, but that is not [Mark Rehorst]’s style. He tried to build a Z-axis drive for his 3D printer around an inexpensive worm gear from AliExpress. This project was doomed by a gear flaw invisible to the human eye, but he documented the experience so we could all follow along.

We’ve featured [Mark]’s projects for his ever-evolving printer before, because we love reading his well-documented upgrade adventures. He’s not shy about exploring ideas that run against 3D printer conventions, from using belts to drive the Z-axis to moving print cooling fan off the print head (with followup). And lucky for us, he’s not shy about document his failures alongside the successes.

He walks us through the project, starting from initial motivation, moving on to parts selection, and describes how he designed his gearbox parts to work around weaknesses inherent to 3D printing. After the gearbox was installed, the resulting print came out flawed. Each of the regularly spaced print bulge can be directly correlated to a single turn of the worm gear making it the prime suspect. Then, to verify this observation more rigorously, Z-axis movement was measured with an indicator and plotted against desired movement. If the problem was caused by a piece of debris or surface damage, that would create a sharp bump in the plot. The sinusoidal plot tells us the problem is more fundamental than that.

This particular worm gear provided enough lifting power to move the print bed by multiplying motor torque, but it also multiplied flaws rendering it unsuitable for precisely positioning a 3D printer’s Z-axis. [Mark] plans to revisit the idea when he could find a source for better worm gears, and when he does we’ll certainly have the chance to read what happens.

How To Build Anything Out Of Aluminum Extrusion And 3D Printed Brackets

May 8, 2018 by Roger Cheng 42 Comments

The real power of 3D printing is in infinite customization of parts. This becomes especially powerful when you combine 3D printing with existing materials. I have been developing a few simple tricks to make generic fasteners and printed connectors a perfect match for aluminum extrusion, via a novel twist or two on top of techniques you may already know.

Work long enough with 3D printers, and our ideas inevitably grow beyond our print volume. Depending on the nature of the project, it may be possible to divide into pieces then glue them together. But usually a larger project also places higher structural demands ill-suited to plastic.

Those of us lucky enough to have nice workshops can turn to woodworking, welding, or metal machining for larger projects. Whether you have that option or not, aluminum extrusion beams provide the structure we need to go bigger and to do it quickly. And as an added bonus, 3D printing can make using aluminum extrusion easier and cheaper.

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