Fancy Filament Joiner Has Promise, But Ultimately Fails

December 17, 2020 by Lewin Day 29 Comments

[Proper Printing] has been trying to 3D print rims for his car for quite some time. However, the size of the print has led to problems with filament spools running out prior to completion. This led to endless headaches trying to join several smaller lengths of filament in order to make a single larger spool. After his initial attempts by hand failed, a rig was built to try and bring some consistency to the process. (Video, embedded below.)

The rig consists of a heater block intended to melt the ends of two pieces of filament so that they can be fused together. A cheap set of brass calipers was modified with a tube in order to form a guide for the filament, ensuring that it gets bonded neatly without flaring out to a larger size. Fan coolers are then placed either side of the heating area to avoid turning the whole filament into a hot mess.

Unfortunately, the rig simply didn’t work. The initial design simply never got the filament hot enough, with the suspicion being that heat was instead being dumped into the calipers instead of the filament itself. Modifications to reduce this sadly didn’t help, and in the end, more success was had by simply holding a lighter below a length of brass tube.

While the project wasn’t a success, there’s still value in the learning along the way. We can’t see any fundamental reason why such a rig couldn’t be made to work, so if you’ve got ideas on how it could be improved, sound off in the comments. We’ve seen other successful builds using hair straighteners in a relatively simple setup, too.

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3D Printing With VHS Tape Filament

December 16, 2020 by Bryan Cockfield 53 Comments

If you have a pile of old VHS tapes collecting dust in your attic or basement that you know you’ll never watch again, either because all of those movies are available on DVD or a streaming service, or because you haven’t had a working VCR since 2003, there might be a way of putting them to good use in another way. With the miles of tape available in just a few cassettes, [brtv-z] shows us how to use that tape as filament for a 3D printer.

The first step of the build is to actually create the filament. He uses a purpose-built homemade press to spin several tapes into one filament similar to how cotton or flax is spun into yarn. From there the filament is simply fed into the 3D printer and put to work. The tape filament needs to be heated higher than a standard 3D printer filament so he prints at a much slower rate, but the resulting product is indistinguishable from a normal print except for the color. It has some other interesting properties as well, such as retaining its magnetism from the magnetic tape, and being a little more brittle than PET plastic although it seems to be a little stronger.

While the VHS filament might not be a replacement for all plastic 3D prints, it’s still a great use for something that would likely otherwise head straight to the landfill. There are some other uses for this magnetic tape as well, like if you wanted to build a DIY particle accelerator.

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Creality WiFi Takes On Octoprint

December 13, 2020 by Al Williams 78 Comments

A very common hack to a 3D printer is to connect a Raspberry Pi to your printer and then load Octoprint or a similar program and send your files to the printer via the network. [Teaching Tech] noticed that Creality now has an inexpensive WiFi interface that promises to replace Octoprint and decided to give it a quick review.

You might wonder why you’d want this system when Octoprint exists? Mainly, the value proposition is the price. You can buy the Creality box for about $20. A Raspberry Pi with a similar case would be at least twice that price. In addition, the box integrates with a Thingiverse-like library and does cloud slicing, which is attractive when you have a very small computer connected to your printer.

However, [Teaching Tech] found some issues. The box was pretty picky about connecting to printers and there were many other problems. The 3D model library wasn’t very comprehensive, although that could change if the thing got very popular. Worse, the slicer didn’t really produce stellar results.

We have to admit, an attractive network interface for $20 would be of interest. But it is hard to see how this would be a better value than Octoprint unless you were very short on cash and had no Raspberry Pi surplus laying around. You still need an SD card and a power supply, so those extras are a wash.

On the other hand, if Creality fixes the problems and expands the 3D model library, we’d buy one. But it remains to be seen if either of those things will happen, much less both of them. We do wish [Teaching Tech] had opened the thing up for us. Maybe next time.

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Slick DIY Compound Bow Uses Coiled Springs, Toothbrush Heads

December 12, 2020 by Donald Papp 14 Comments

Compound bows (unlike recurve bows, their more mechanically-simple relatives) use a levering system with pulleys and spring tension to grant the user a mechanical advantage. We’re not exactly sure what to call [Zünder’s] bow design. He shared his unconventional take on a DIY bow that uses coiled springs as well as some other unique features.

Toothbrush heads and 3D printing make an enclosed, bristle-supported arrow rest.

What we really dig about [Zünder]’s design is how easy it is to grasp how it all works. As he demonstrates using the bow, the way the levers, pulleys, and spring tension all work together is very clear. The 3D-printed quiver and arrow rest are nice added touches, and we especially love the use of three toothbrush heads to provide contained support for a nocked arrow. The ring of bristles are sturdy enough to easily support the shaft, and don’t interfere with the arrow’s fletching.

[Zünder] has a photo gallery with a few additional photos and closeups, and you can watch him demonstrate his bow in the video embedded below.

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A Walking Rover Destined Explore Your Fridge Door

December 10, 2020 by Danie Conradie 7 Comments

It’s usually the simple ideas that sprout bigger ones, and this was the case when we saw [gzumwalt]’s single-motor walking robot crawling up a fridge door with magnets on its feet. (Video, embedded below.)

The walking mechanism consists of an inner foot and two outer feet, connected by three sets of rotating linkages, driven by a single geared motor. The feet move in a leapfrog motion, in small enough steps that the center of mass always stays inside the foot area, which keeps it from tipping over. Besides the previously mentioned ability to crawl around on a vertical magnetic surface, it’s also able to crawl over almost any obstacle shorter than its step length. A larger version should also be able to climb stairs.

As shown, this robot can only travel in a straight line, but this could be solved by adding a disc on the bottom of the inner foot to turn the robot when the outer feet are off the surface. Add some microswitch feelers and an Arduino, and it can autonomously explore your fridge without falling off. Maybe we’ll get around to building it ourselves, but be sure to drop us a tip if you beat us to it!

[gzumwalt] is a master of 3D printed devices like a rigid chain and a domino laying robot. The mechanism for this robot was inspired by one design from [thang010146]’s marvelous video library of mechanisms.

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3D Printed Rigid Chain Mechanism

December 8, 2020 by Danie Conradie 34 Comments

One of the major advantages of 3D printing is the ability to quickly test and then iterate on mechanical designs. [gzumwalt] does a lot of this, and has recently been working on various versions of a rigid chain mechanism. (Video, embedded below.)

A rigid-chain mechanism is one way of fitting a long beam into a small box. It works similar to a zipper, meshing two separate “chains” with specially teeth designed to form a rigid beam. Due to clearances between the teeth, the beam tends to be a bit floppy. [gzumwalt] made various sizes of the mechanism, and also reduced the clearances on later versions to reduce the flop. He also integrated it into a cool “snake in a basket” automaton (second video below) by adding a reversible gearbox and a binary snap-action switch.

One possible use for this type of mechanism is for autonomously assembling long structures in space, as one of the 2017 Hackaday Prize finalist projects, ZBeam, proposed.

[gzumwalt] has not made the files available for download yet, but you can keep and eye on his Instructables pages for updates. He got a number of fascinating 3D printed devices already available, like a domino laying machine or a WiFi controlled rover.

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Food Safe Printing Techniques

December 7, 2020 by Al Williams 10 Comments

One thing that always provokes spirited debate around the Hackaday bunker is just how dangerous is it to use 3D printed plastic in contact with food. We mostly agree it isn’t a good thing, but we also know some people do it regularly and they don’t drop dead instantly, either. [Jakub] decided to do some testing and make some recommendations. There’s even a video explaining the results.

Unlike a lot of what we’ve read about this topic in the past, [Jakub’s] post is well-researched and does actual testing including growing bacteria cultures from cups used for milk. He starts out identifying the EU and US regulations about what you can call food-grade. There’s also recognition that while a base plastic might be safe for contact with food, there’s no way to know exactly what additives and other things are in the plastic to change its properties and color.

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