Epoxy Too Thin? Use Wood Flour As A Thixotropic Filler

December 23, 2018 by Donald Papp 27 Comments

The world of glues is wide and varied, and it pays to use the right glue for the job. When [Eric] needed to stick a wide and flat 3D printed mount onto the back of a PCB that had been weatherproofed with an uneven epoxy coating, he needed a gap-filling adhesive that would bond to both surfaces. It seemed like a job for the hot glue gun, but the surface was a bit larger than [Eric] was comfortable using with hot glue for. The larger the surface to be glued, the harder it is to do the whole thing before hot glue cools too much to bond properly.

What [Eric] really wanted to use was a high quality two-part epoxy that he already had on hand, but the stuff was too runny to work properly for this application. His solution was to thicken it with a thixotropic filler, which yields a mixture that is akin to peanut butter: sticky, easily spread to where it’s needed, but otherwise stays in place without dripping or sagging and doesn’t affect bonding.

3D printed pad stuck to back of PCB with thickened epoxy.

Common thixotropic fillers include ground silica or plastic fibers, but [Eric]’s choice was wood flour. Wood flour is really just very fine sawdust, and easily obtained from the bag on his orbital sander. Simply mix up a batch of thin two-part epoxy and stir in some wood flour until the sticky mixture holds its shape. Apply as needed, and allow it to cure.

Thanks to this, [Eric] was able to securely glue a 3D printed pad to the back of his animated LED snowflakes to help mount them in tricky spots. Whether for small projects or huge installations, LEDs, PCBs, and snowflakes are a good combination.

Manual 3D Digitizer Works A Bit Like 3-Dimensional Measuring Tape

December 21, 2018 by Donald Papp 26 Comments

Digitizing an object usually means firing up a CAD program and keeping the calipers handy, or using a 3D scanner to create a point cloud representing an object’s surfaces. [Dzl] took an entirely different approach with his DIY manual 3D digitizer, a laser-cut and 3D printed assembly that uses rotary encoders to create a turntable with an articulated “probe arm” attached.

Each joint of the arm is also an encoder, and by reading the encoder values and applying a bit of trigonometry, the relative position of the arm’s tip can be known at all times. Manually moving the tip of the arm from point to point on an object therefore creates measurements of that object. [Dzl] successfully created a prototype to test the idea, and the project files are available on GitHub.

We remember the earlier version of this project and it’s great to see how it’s been updated with improvements like the addition of a turntable with an encoder. DIY 3D digitizing takes all kinds of approaches, and one example was this unit that used four Raspberry Pi Zeros and four cameras to generate high quality 3D scans.

How Not To Design A 3D Printed Belt Clamp

December 16, 2018 by Donald Papp 17 Comments

[Mark Rehorst] has been busy with his Ultra MegaMax Dominator (UMMD) design for a 3D printer, and one of the many things he learned in the process was how not to design a 3D printed belt clamp. In the past, we saw how the UMMD ditched the idea of a lead screw in favor of a belt-driven Z axis, but [Mark] discovered something was amiss when the belts were flopping around a little, as though they had lost tension. Re-tensioning them worked, but only for a few days. It turned out that the belt clamp design he had chosen led to an interesting failure.

The belts used were common steel-core polyurethane GT2 belts, and the clamp design uses a short segment of the same belt to lock together both ends, as shown above. It’s a simple and effective design, but one that isn’t sustainable in the longer term.

The problem was that this design led to the plastic portion of the belt stretching out and sliding over the internal steel wires. The stretching of the polyurethane is clear in the image shown here, but any belt would have had the same problem in the clamp as it was designed. [Mark] realized it was a much better idea to use a design in which the belts fold over themselves, so the strain is more evenly distributed.

[Mark] has been sharing his experiences and design process when it comes to building 3D printers, so if you’re interested be sure to check out the UMMD and its monstrous 695 mm of Z travel.

Lessons Learned From A 1-Day RTL-SDR Enclosure Project

December 14, 2018 by Donald Papp 9 Comments

[ByTechLab] needed an enclosure for his R820T2 based RTL-SDR, which sports an SMA connector. Resolving to design and 3D print one in less than a day, he learned a few things about practical design for 3D printing and shared them online along with his CAD files.

The RTL-SDR is a family of economical software defined radio receivers, and [ByTechLab]’s’ enclosure (CAD files available on GrabCAD and STL on Thingiverse) is specific to his model. However, the lessons he learned are applicable to enclosure design in general, and a few of them specifically apply to 3D printing.

He started by making a basic model of the PCB and being sure to include all large components. With that, he could model the right voids inside the enclosure to ensure a minimum of wasted space. The PCB lacks any sort of mounting holes, so the model was also useful to choose where to place some tabs to hold the PCB in place. That took care of the enclosure design, but it also pays to be mindful of the manufacturing method so as to play to its strengths. For FDM 3D printing, that means most curved shapes and rounded edges are trivial. It also means that the biggest favor you can do yourself is to design parts so that they can be printed in a stable orientation without any supports.

This may be nothing that an experienced 3D printer and modeler doesn’t already know, but everyone is a novice at some point and learning from others’ experiences can be a real timesaver. For the more experienced, we covered a somewhat more in-depth guide to practical 3D printed enclosure design.

[ByTechLab]’s desire for a custom enclosure was partly because RTL-SDR devices come in many shapes and sizes, as you can see in this review of 19 different units (of which only 14 actually worked.)

Soft Silicone Pneumatics Are 3D-printed In A Tub Of Gel

November 27, 2018 by Brian Boucheron 28 Comments

We’ve seen our fair share of soft silicone robots around here. Typically they are produced through a casting process, where molds are printed and then filled with liquid silicone to form the robot parts. These parts are subsequently removed from the molds and made to wiggle, grip, and swim through the use of pneumatic or hydraulic pumps and valves. MIT’s Self-Assembly Lab has found a way to print the parts directly instead, by extruding silicone, layer by layer, into a gel-filled tank.

The Self-Assembly Lab’s site is unfortunately light on details, but there is a related academic paper (behind a paywall, alas) that documents the process. From the abstract, it seems the printing process is intended for more general purpose printing needs, and is able to print any “photo or chemically cured” material, including two-part mixtures. Additionally, because of the gel-filled tank, the material need not be deposited in flat layers like a traditional 3D-printer. More interesting shapes and material properties could be created by using the full 3d-volume to do 3D extrusion paths.

To see some of the creative shapes and mechanisms developed by MIT using this process, check out the two aesthetically pleasing videos of pulsating soft white silicone shapes after the break.

Continue reading “Soft Silicone Pneumatics Are 3D-printed In A Tub Of Gel” →

Tiny Drone Racing Gates Use Up Those Filament Scraps

November 27, 2018 by Donald Papp 6 Comments

Drone racing comes in different shapes and sizes, and some multirotor racers can be very small indeed. Racing means having gates to fly though, and here’s a clever DIY design by [Qgel] that uses a small 3D printed part and a segment of printer filament as the components for small-scale drone racing gates.

The base is 3D printed as a single piece and is not fussy about tolerances, meanwhile the gate itself is formed from a segment of printer filament. Size is easily adjusted, they disassemble readily, are cheap to produce, and take up very little space. In short, perfect for its intended purpose.

Races benefit from being able to measure lap time, and that led to DIY drone racing transponders, complete with a desktop client for managing the data. Not all flying is about racing, but pilots with racing skills were key to getting results in this Star Wars fan film that used drones. Finally, those who still feel that using the word “drone” to include even palm-sized racers is too broad of a use may be interested in [Brian Benchoff]’s research into the surprisingly long history of the word “drone” and its historically broad definition.

The Most-3D-Printed 3D Printer

November 27, 2018 by Inderpreet Singh 46 Comments

The most awesome things about having a 3D printer is that you can create almost anything which includes parts for the 3D printer itself. Different materials give power to your imagination and allow you to go beyond the 3D printed vase. So much so that one maker has gone as far as 3D print the bearings as well as the axis screws and nuts and it works!

The RepRap project was the first project to incorporate 3D printed parts to make it self-replicating to a certain extent. The clamps and mounts could be easily printed, however, this project uses a 3D printed frame as well as two linear bearings for the y-axis and z-axis and one for the x-axis. The y-axis is a 3D printed rack-and-pinion while the z-axis is made of a 3D printed screws and nuts. So basically, the servo motors, extruder/hotend and limits switches with mounting screws are the only part that need be bought at the store.

Even though in motors are running hot causing mounts to get soft, heat-sinks are predicted to resolve the issue. This one is not designed for accuracy though it can be a great resource for budding engineers and hackers to get their feet wet with customizing 3D printers. Check out the video for a demo.

From 3D printed guitars to RC Planes, there is a lot you can do with micro-manufacturing and all we need now is a 3D printed motor to get things rolling. Continue reading “The Most-3D-Printed 3D Printer” →