Researchers at the University of Texas have been experimenting with optical 3D printing using near infrared (NIR) light instead of the more traditional ultraviolet. They claim to have a proof of concept and, apparently, using NIR has many advantages. The actual paper is paywalled, but there are several good summaries, including one from [3D Printing Industry].
UV light degrades certain materials and easily scatters in some media. However, decreasing the wavelength of light used in 3D printing has its own problems, notably less resolution and slower curing speed. To combat this, the researchers used an NIR-absorbant cyanine dye that exhibits rapid photocuring. The team reports times of 60 seconds per layer and resolution as high as 300 micrometers. Nanoparticles in the resin allow tuning of the part’s appearance and properties.
Some people like crossword puzzles, some are serious sudoku ninjas, but [Andrea Favero] likes to keep himself sharp, by learning coding and solving control problems, and that is something we can definitely relate to. When learning a new platform, it’s a very good idea to have a substantial project or goal in mind, and learn what is needed on the way there. [Andrea] chose to build an autonomous Rubik’s cube solver, and was kind enough to document exactly how how to do it, and we’re glad of it!
The result of the openCV processing chain
Working in python with OpenCV, [Andrea] uses the methodology by [Oussama Barkouki] to process each face image and convert it into a table of the colours of individual facelets. The basics of that, are first to convert the image to grayscale, then use a gaussian blur to denoise the image. Edges are identified using the canny algorithm, the result of which is then dilated and passed into a contour detector. The contours are sent into a cunning filter that identifies square contours, and those the wrong size are filtered off. What you’re left with are the outlines of the actual coloured facelets. Once you have a list of squares, these can be used to form image masks, and thence select the average colour from each square. The colour is then quantised and stored as a labelled colour from the standard Western Rubik’s cube colour scheme. Finally, once all face images are captured and facelets colours identified, the data are passed into a Rubik’s cube solving algorithm developed by [Hegbert Kociemba,] a guide to which is available on the speedsolving site. The result of the solving step is a sequence of descrambling moves, in the move notation developed by [David Singmaster]. Fascinating stuff, if you ask us! Continue reading “Forget Sudoku, Build Yourself A Minimalist Rubik’s Solver Robot”→
When mathematically inspired maker [Henry Segerman] conspired with circus performer and acrobat [Marcus Paoletti] to advance the craft of acrobatics in round metal objects (such as cyr wheels and German Wheels), they came up with a fascinating concept that has taken shape in what [Henry] calls the Tao-Line.
Similar performance devices go in a straight line or can be turned on edge, but the Tao-Line is far more nimble. This is because the Tao-Line is not a continuous cylinder, but rather is made up of numerous circular shapes that allow the Tao-Line to be turned and inverted at different points in its rotation.
While a circus prop might not be your average Hackaday fare, it’s noteworthy because the Tao-Line started off as a 3D printed prototype, which was then turned into the metal fabrication you see in the video below the break. It’s an excellent example of how modeling complex shapes as a physical product- not just a 3D model on the screen- can be helpful in the overall design and construction of the full scale piece.
If you’re looking to build something that’s under the big top but not quite so over the top, you might enjoy this mixed-media digital clock. Thanks to [Keith] for the great tip. Be sure to submit send your cool finds via the Tip Line!
There’s an old joke about the Thermos bottle that keeps things hot and cold, so someone loaded it with soup and ice cream. That joke is a little close to home when it comes to FDM 3D printers.
You want to melt plastic, of course, or things won’t print, so you need heat. But if the plastic filament gets hot too early, it will get soft, expand, and jam. Heat crawling up the hot end like this is known as heat creep and there are a variety of ways that hot ends try to cope with the need to be hot and cold at the same time. Most hotends today are air-cooled with a small fan. But water-cooled hotends have been around for a while and are showing up more and more. Is it a gimmick? Are you using, planning to use, or have used (and abandoned) water cooling on your hot end?
Heat Break
The most common method is to use a heat-break between the heating block and the rest of the filament path. The heat-break is designed to transfer as little heat as necessary, and it usually screws into a large heat sink that has a fan running over it. What heat makes it across the break should blow away with the fan cooling.
High tech solutions include making heat-breaks out of titanium or even two dissimilar metals, all with the aim of transferring less heat into the cooler part of the hot end. More modern hot ends use support structures so the heatbreak doesn’t need mechanical rigidity, and they can make very thin-walled heatbreaks that don’t transmit much heat. Surely, then, this is case closed, right? Maybe not.
While it is true that a standard heat-break and a fan can do the job for common 3D printing tasks, there can be problems. First, if you want to print fast — time is money, after all — you need more power to melt more filament per second. If a heatbreak transfers 10% of the heat, this increases demands on the upstream cooling. Some engineering materials want to print at higher temperatures, so you can have the same problem there as well. If you want to heat the entire print chamber, which can help with certain printing materials, that can also cause problems since the ambient air is now hotter. Blowing hot air around isn’t going to cool as effectively. Not to mention, fans that can operate at high temperatures are notoriously expensive.
There are other downsides to fans. Over a long print, a marginal system might eventually let enough heat creep up. Then there’s the noise of a fan blowing during operation. True, you probably have other fans and noisy parts, but it is still one more noise source. With water cooling, you can move the radiator outside a heated enclosure and use larger, slower, and quieter fans while getting more cooling right where you want it. Continue reading “3D Printering: Water-Cooled Hotends”→
We often use 3D printing to replicate items we might otherwise make with traditional machining methods. Fraunhofer’s new door hinge for a sports car takes a different tack: it tries to be better than the equivalent machined part. The company claims that the new part is half the cost and weighs 35% less than the normal hinge.
Using tools in their 3D Spark software, the team analyzed different factors that led to manufacturing cost. Some of these were specific to the part while others were specific to the process. For example, orienting the part to minimize support and maximize the quantity that fit on the build surface.
When you think of making something out of silicone, you usually think of using a mold and injecting it with the material. Can you 3D print it? [Kimberly Beckett] answers that very question in a recent post. The short answer is yes, but you need specialized printing equipment.
Most consumer or hobby printers use either filament deposition or photoresin. Neither of these processes are good for printing silicone. For one thing, silicone doesn’t melt and reform like a thermoplastic. After all, that is why we like making hotend socks and oven utensils with the material. If you do melt silicone, you get a gooey mess, not a nice fluid you can push through an extruder nozzle. As for resin printing, silicone is resistant to UV so the chances of coming up with UV curable silicone are pretty small.
Since the dawn of the age of the automobile, motorheads have been obsessed with using as few wheels as possible. Not satisfied with the prospect of being incompletely maimed by a motorcycle, the monocycle was born. Gracing the covers of Popular magazines and other periodicals, these futuristic wheels of doom have transfixed hackers of all kinds. [James Bruton] is one such hacker, and in the video below the break you can see his second iteration of a 3d printed monowheel.
[James]’ wonderful monowheel is beautifully engineered. Bearing surfaces, gears, idlers, motors, and yes, twin gyroscopes are all contained within the circumference of the tire. The gyroscopes are actuated by a rather large servo, and are tied together by a gear that keeps their positions in sync. Their job is to keep the monowheel balanced at all times.
But as [James] discovered, the chief difficulty of only having one wheel isn’t lateral balancing. Ask any monocyclist and they’ll assure you that it’s possible. The real trick is balancing the machine fore and aft. Unlike a two wheeled velocipede, the monowheel has nothing to exert torque against save for a bit of gravity.
As [James] found out the hard way, it was within this fore-aft balancing act that the gyroscopic precession reared its ugly head. The concept is explained well in the video. We won’t spoil the surprise ending because the explanation and conclusion are quite good so make sure to watch to the end!
