3d printing

867 Articles

OpenDog: Adding Force Sensitive Feet

January 4, 2020 by 16 Comments

[James Bruton] OpenDog remains one of the most impressive home-built robotics projects we’ve seen here on Hackaday, and it’s a gift that just keeps on giving. This time he’s working on adding force sensing capabilities to OpenDog’s legs to allow for more dynamic movement control.

The actuators in the legs are three-phase outrunner motors that drive ball-screws via a belt. This configuration is non-backdrivable, meaning the legs cannot be moved when an external force is, which could lead to mechanical failures. He as tested other backdrivable leg configurations with other robots, but did not want to rebuild OpenDog completely. The solution [James] went with is a redesigned foot with an inbuilt switch, to confirm that the foot is touching the ground, and a load cell attached in the middle of the bottom leg segment. The load cell is bolted rigidly onto the leg segment, which allows it to sense when the leg is carrying load, without damaging the load cell itself.

Unfortunately all the serial ports on OpenDog’s main Teensy 3.6 controller are already used, so he converted the signal from the load cell to PWM, to allow it to be read by a normal GPIO pin. This works well in isolation, but when [James] switches on the motors, the PWM signal from the load sensor gets flooded by interference, making it unreadable. To solve this problem, he wants to implement a CAN bus, which will allow for more inputs and outputs and hopefully solve the interference problem. However, [James] has no experience with the CAN protocol, so learning to use it is going to be a project on its own.

OpenDog is turning into a very lengthy, time-consuming project, [James] says that the lessons learned from it have been invaluable for a number of other projects. This is something to keep in mind with everything we tackle. Choose projects were the experience gained and/or relationships developed are worth it on their own, even when the project fails in a conventional sense. This way you can never really lose.

Stronger 3D Prints — Glue Or Carbon Fiber?

December 28, 2019 by 31 Comments

[CNCKitchen], like many others, is looking to make strong 3D prints. Using a high tech PLA bio copolyester compound, he printed a bunch of hooks in two different orientations. He used several different types of glue including epoxy and superglue. You can see the video of his results, below.

In addition to the glue, he used epoxy and bulk carbon fiber, again, in two different orientations. After several days of curing, he was ready to test.

Continue reading “Stronger 3D Prints — Glue Or Carbon Fiber?” →

3D Printed Pulsejet Uses Tesla Valve

December 27, 2019 by 18 Comments

For most people, a jet is a jet. But there are several different kinds of jet engines, depending on how they operate. You frequently hear about ramjets, scramjets, and even turbojets. But there is another kind — a very old kind — called a pulsejet. [Integza] shows how he made one using 3D printed parts and also has a lot of entertaining background information. You can see the video below. (Beware, there is a very little bit of off-color language and humor in the video, so you might not want to watch this one at work.)

They are not ideal from a performance standpoint, but they are easy to make. How easy? A form of pulsejet was accidentally discovered by a young Swiss boy playing with alcohol in the early 1900s. Because of their simplicity, they’ve been built by lots of different people, including rocket pioneer Robert Goddard, who mounted one to a bicycle.

Continue reading “3D Printed Pulsejet Uses Tesla Valve” →

3D Printing Paper — Sort Of

December 26, 2019 by 31 Comments

There are only a few truly ancient engineered materials, and among the oldest is paper. Traditionally, paper is flat and can be bent into shapes. However, paper can be molded into for example packing material or egg cartons. [XYZAidan]  has a process that can recycle paper into 3D cardboard-like objects. You need a 3D printer, but it doesn’t actually print the paper. Instead, you use the printer to create a mold that can form paper pulp you make out of recycled paper and a blender.

[Aidan] provides seven different molds ranging from a desk tray and a dish to simple cubes and coasters. The molds are made in three parts to assist in removing the finished product.

Continue reading “3D Printing Paper — Sort Of” →

Folding An Off-The-Shelf 3D Printer

December 26, 2019 by 14 Comments

Most 3D printers don’t take up a lot of space, but they can be pretty bulky and awkward to travel with. [Jón Schone] needed a compact folding 3D printer for a secret project on his YouTube channel ProperPrinting, so he decided to modify a Creality Ender 3 Pro to achieve this.

Starting with a brand new Ender 3 Pro, and his first steps were to move the display and power supply unit into the bottom frame to make space for the folding top frame. For the folding mechanism, he settled on a four bar linkage that allows the vertical frame to translate to the front of the printer as it folds down, which lets it become a really compact package with minimal wasted space. The joints consist of fitting 3D printed in carbon fibre reinforced nylon, with bolts for shafts. The entire mechanism is made adjustable for fine-tuning by using threaded rod and sliding mounting points on the extruded frame. Small brackets on each side of the frame allows the printer to snap securely into both its upright and folded positions.

All in all we think this is well-designed and beautifully executed hack, enough to make us really want to build one for ourselves. It will remain to be seen if any slop develops with repeated folding and use, especially at the snap-in end stops, but that should still be an easy fix if it happens.

We’ve previously featured [Jón]’s custom 3D printed D-sub connectors, also for his Ender 3. Also check out another folding printer, the X-printer.

Continue reading “Folding An Off-The-Shelf 3D Printer” →

Finishing FDM Prints With SLS Resin

December 25, 2019 by 17 Comments

[Thomas Sanladerer] has a filament-based 3D printer and a resin one. Can the two types of raw material combine to make something better? [Thomas] did some experiments using some magnets to suspend the parts and a hot air soldering gun to heat things up.

The trick turns out to be cutting the resin with alcohol. Of course, you also need to use a UV light for curing.

The parts looked pretty good, although he did get different results depending on a few factors. To see how it would work on a practical part, he took a very large printed alien egg. The problem is, the egg won’t fit in the curing station. A few minutes with a heat sink, a drill press, and an LED module was all it took to build a handheld UV curing light.

The good news is you don’t need a resin printer to take advantage of the process — just the resin. He also points out that if you had parts which needed to maintain their dimensions because they mate with something else, you could easily mask the part to keep the resin away from those areas.

If this video (and the results it shows) has you interested, then you’ll love the in-depth account that [Donald Papp] wrote up last year about his own attempts to smooth 3D printed parts with UV resin.

Continue reading “Finishing FDM Prints With SLS Resin” →

Annealing 3D Prints: A Scientific Approach

December 18, 2019 by 28 Comments

We’ve all been taught the scientific method: Form a hypothesis, do some experiments, gather some data, and prove or disprove the hypothesis. But we don’t always do it. We will tweak our 3D prints a little bit and think we see an improvement (or not) and draw some conclusions without a lot of data. Not [Josef Prusa], though. His team printed 856 different parts from four different materials to generate data about how parts behaved when annealed. There’s a video to watch, below.

Annealing is the process of heating a part to cause its structure to reorganize. Of course, heated plastic has an annoying habit of deforming. However, it can also make the parts firmer and with less inner tension. Printed parts tend to have an amorphous molecular structure. That is to say, they have no organization at all. The temperature where the plastic becomes soft and able to reorganize is the glass transition temperature.

Continue reading “Annealing 3D Prints: A Scientific Approach” →