No Filament Needed In This Direct Extrusion 3D-Printer

July 8, 2019 by Dan Maloney 22 Comments

Ground plastic bits go in one end, finished 3D-prints come out the other. That’s the idea behind [HomoFaciens]’ latest build: a direct-extrusion 3D-printer. And like all of his builds, it’s made from scraps and bits most of us would throw out.

Pellet agitator is part of the extruder. All of this travels along with the print head.

Take the extrusion screw. Like the homemade rotary encoders [HomoFaciens] is known for, it appears at first glance that there’s no way it could work. An early version was just copper wire wrapped around a threaded rod inside a Teflon tube; turned by a stepper motor, the screw did a decent job of forcing finely ground PLA from a hopper into the hot end, itself just a simple aluminum block with holes drilled into it. That worked, albeit only with basically powdered PLA. Later versions of the extruder used a plain galvanized woodscrew soldered to the end of a threaded rod, which worked with chunkier plastic bits. Paddles stir up the granules in the hopper for an even flow into the extruder, and the video below shows impressive results. We also picked up a few tips, like using engine gasket paper and exhaust sealant to insulate a hot end. And the slip coupling, intended to retract the extruder screw slightly to reduce stringing, seems brilliant but needs more work to make it practical.

It’s far from perfect, but given the inputs it’s pretty amazing, and there’s something attractive about reusing all those failed prints. It reminds us a bit of the trash printer we featured recently, which is another way to stick it to the filament man. Continue reading “No Filament Needed In This Direct Extrusion 3D-Printer” →

Printable Filament Spool Hub Skips The Bearings

March 16, 2019 by Tom Nardi 32 Comments

When you really start fine-tuning your 3D printer, you might start to notice that even the smallest things can have a noticeable impact on your prints. An open window can cause enough of a draft to make your print peel up from the bed, and the slightly askew diameter of that bargain basement filament can mess up your extrusion rate. It can be a deep rabbit hole to fall down if you’re not careful.

One element that’s often overlooked is the filament spool; if it’s not rotating smoothly, the drag it puts on both the extruder and movement of the print head can cause difficult to diagnose issues. For his custom built printer, [Marius Taciuc] developed a very clever printable gadget that helps the filament roll spin using nothing but the properties of the PLA itself. While the design might need a bit of tweaking to work on your own printer, the files he’s shared should get you most of the way there.

All you need to do is print out the hubs which fit your particular filament spools (naturally, they aren’t all a standard size), and snap them on. The four “claws” of the hub lightly contact a piece of 8 mm rod enough to support the spool while limiting the surface area as much as possible. The natural elasticity of PLA helps dampen the moment that would result if you just hung the hub-less spool on the rod.

The STL files [Marius] has provided for his low-friction hubs should work fine for anyone who’s interested in trying out his design, but you’ll need to come up with your own method of mounting the 8 mm rod in a convenient place. The arms he’s included are specifically designed for his customized Prusa Mendel, which is pretty far removed from contemporary desktop 3D printer design. Something to consider might be a piece of 8 mm rod suspended over the printer, with enough space that you could put a couple spools on for quick access to different colors or materials.

Hackers have been trying to solve the spool friction issue for years, and as you might expect we’ve seen some very clever designs in the past. But we especially like how simple [Marius] has made this design, and the fact that you don’t need to source bearings to build it. If you’re thinking of giving this new design a shot, be sure to leave a comment so we know how it worked out for you.

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The Filament Pelletizer For Fused Granular Fabrication

December 5, 2018 by Brian Benchoff 24 Comments

The ABS and PLA that goes into your 3D printer is sold in two forms. The first, naturally, is filament. The second is plastic granules, the raw material for your filament, and costs an order of magnitude less than the filament itself. For years we’ve been seeing machines that either print directly with plastic granules or are converted into filament with fancy filament-extruding machines. Now we can do it the other way. [Aubrey Woern] and [Joshua Pearce] of Michigan Tech have been working on a polymer pelletizer chopper that takes plastic filament and turns it into pellets.

The system uses a large corded drill motor to drive a Forstner drill bit. Filament is then threaded into the top of this spinning drill bit with the help of a small DC motor and grippy wheel printed out of Ninjaflex. The system works, and the authors of the paper were able to vary the size of the chopped filament by feeding it into the Forstner bit faster or slower.

While turning an expensive product (filament) back into its raw material (pellets) may not seem like a great idea, there have been a significant number of advancements in the state of manufacturing filament on a desktop and printing directly from pellets in recent years. A machine that turns plastic back into its raw state is something that’s needed if you want to experiment with plastic recycling, and this machine is more than capable of chopping up a spool of filament in two hours or so.

PLA Foils Homemade Tachometer

November 22, 2018 by Al Williams 19 Comments

[Integza] built a Tesla turbine and wanted to know how fast it was spinning. However, he didn’t have a tachometer, and didn’t want to buy one. After a false start of trying to analyze the audio to measure the speed, he decided to use a tried-and-true method. Let the wheel break an infrared (IR) optointerruptor and count the spokes of the wheel as they go by. If you know the spacing between the spokes, you can compute the speed. There was only one problem: it didn’t work.

Turns out, PLA is at least somewhat transparent to IR. Knowing that it was a simple matter to fix some tape to the wheel that would block IR and that made things work much better. If you missed the video where he built the turbine, you might want to watch it first.

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Prusa Unveils Their Own Line Of PLA Filament

September 21, 2018 by Tom Nardi 33 Comments

There’s little debate that the Original Prusa i3 MK3 by Prusa Research is just about the best desktop 3D printer you can buy, at least in its price bracket. It consistently rates among the highest machines in terms of print quality and consistency, and offers cutting edge features thanks to its open source iterative development. Unless you’re trying to come in under a specific budget, you really can’t go wrong with a Prusa machine.

But while the machine itself can be counted on to deliver consistent results, the same can’t always be said for the filament you feed into it. In a recent blog post, [Josef Prusa] explains that his team was surprised to see just how poor the physical consistency was on even premium brands of 3D printer filament. As a company that prides itself with keeping as much of the 3D printing experience under their control as possible, they felt they had an obligation to do better for their customers. That’s why they’ve started making their own filament which they can hold to the same standards as the rest of their printer.

Their new filament, which is aptly called “Prusament”, is held to higher physical standards of not only diameter but ovality. Many manufacturers simply perform spot checks on the filament’s diameter, but this can miss bulges or changes in its cross-sectional shape. On your average 3D printer this might cause some slightly uneven extrusion and a dip in print quality, but likely not a failure. But the Prusa i3 MK3, specifically with the Multi Material upgrade installed, isn’t most printers. During testing even these slight variations were enough to cause jams.

But you won’t have to take their word for it. Every spool of Prusament will have a QR code that points to a page which tells you the exact production date, length, percent ovality, and standard diameter deviation of that particular roll. An interactive graph will even allow you to find the filament’s diameter for a specific position in the spool, as well as determine how much filament is remaining for a given spool weight. It should be very interesting to see what the community will do with this information, and we predict some very interesting OctoPrint plugins coming down the line.

Prusament is currently only available in PLA, but PETG and ASA variants are coming soon. You can order it now directly from Prusa Research in Prague for $24.99 per kilogram, but it will also be available on Amazon within the month for help keep the shipping costs down.

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PLA: The Plastic That Grows

September 12, 2018 by Dan Maloney 67 Comments

If you’ve ever taken a coast-to-coast car trip across the United States, the one thing that’s sure to impress you is the mind-bogglingly immense amount of corn that we grow here. If you take the northern route — I’ve done it seven times, so I know it by heart — you’ll see almost nothing but corn from Ohio to Montana. The size of the fields is simply staggering, and you’re left wondering, “Do we really eat all this corn?”

The simple answer is no, we don’t. We grow way more corn than we can eat or, once turned into alcohol, drink. We do feed a lot to animals, many of which subsequently end up as burgers or pork chops. But even after all that, and after accounting for exports, we still have a heck of a lot of corn to put to work. There are lots of industrial uses for this surplus corn, though, and chances are pretty good you’ve got an ear or two worth coiled up next to your 3D-printer, in the form of polylactic acid, or PLA.

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Tariff Expansion Set To Hit 3D-Printing Right In The Filament

August 12, 2018 by Dan Maloney 139 Comments

Mere weeks after tariffs were put into place raising the cost of many Chinese-sourced electronics components by 25%, a second round of tariffs is scheduled to begin that will deal yet another blow to hackers. And this time it hits right at the heart of our community: 3D-printing.

A quick scan down the final tariff list posted by the Office of the US Trade Representative doesn’t reveal an obvious cause for concern. In among the hundreds of specific items listed one will not spot “Filaments for additive manufacturing” or anything else that suggests that 3D-printing supplies are being targeted. But hidden in the second list of tariff items, wedged into what looks like a polymer chemist’s shopping list, are a few entries for “Monofilaments with cross-section dimension over 1 mm.” Uh-oh!

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