FDM Filament Troubles: Keeping Hygroscopic Materials From Degrading

July 17, 2024 by Maya Posch 18 Comments

Despite the reputation of polymers used with FDM 3D printing like nylon, ABS, and PLA as being generally indestructible, they do come with a whole range of moisture-related issues that can affect both the printing process as well as the final result. While the concept of ‘baking’ such 3D printing filaments prior to printing to remove absorbed moisture is well-established and with many commercial solutions available, the exact extent to which these different polymers are affected, and what these changes look like on a molecular level are generally less well-known.

Another question with such hygroscopic materials is whether the same issues of embrittlement, swelling, and long-term damage inflicted by moisture exposure that affects filaments prior to printing affects these materials post-printing, and how this affects the lifespan of FDM-printed items. In a 2022 paper by Adedotun D. Banjo and colleagues much of what we know today is summarized in addition to an examination of the molecular effects of moisture exposure on polylactic acid (PLA) and nylon 6.

The scientific literature on FDM filaments makes clear that beyond the glossy marketing there is a wonderful world of materials science to explore, one which can teach us a lot about how to get good FDM prints and how durable they will be long-term.

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DIY Spacer Increases FDM Flow Rate For Faster, Better Printing

July 12, 2024 by Dan Maloney 8 Comments

The host of problems to deal with when you’re feeling the need for FDM speed are many and varied, but high on the list is figuring out how to melt filament fast enough to accommodate high flow rates. Plus, the filament must be melted completely; a melty outside and a crunchy inside might be good for snacks, but not for 3D printing. Luckily, budget-minded hobbyists can build a drop-in booster to increase volumetric flow using only basic tools and materials.

[aamott]’s booster, which started life as a copper screw, is designed to replace the standard spacer in an extruder, with a bore that narrows as the filament gets closer to the nozzle to ensure that the core of the filament melts completely. Rather than a lathe, [aamott]’s main tool is a drill press, which he used to drill a 0.7 mm bore through the screw using a PCB drill bit. The hole was reamed out with a 10° CNC engraving bit, generating the required taper. After cutting off the head of the screw and cleaning up the faces, he cut radial slots into the body of the booster by threading the blade of a jeweler’s saw into the bore. The result was a bore wide enough to accept the filament on one end, narrowing to a (roughly) cross-shaped profile at the other.

Stacked up with a couple of knock-off Bondtech CHT nozzles, the effect of the booster was impressive — a 50% increase in flow rate. It’s not bad for a prototype made with simple tools, and it looks a little easier to build than [Stefan]’s take on the same idea.

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Thermoelectric Module Keeps Printer Filament Cool And Dry

June 5, 2024 by Dan Maloney 57 Comments

Anyone who has left their car windows open during a rainstorm will tell you the best way to dry the upholstery is to crank the AC and close the windows. A couple of hours later, presto — dry seats. The same can be said for 3D printer filament, and it’s pretty much what [Ben Krejci] is doing with this solid-state filament dryer.

The running gear for this build is nothing fancy; it’s just a standard thermoelectric cooling module and a fan. The trick was getting the airflow over the module right. [Ben] uses two air inlets on his printed enclosure to pull air from the cold side of the Peltier, which allows the air enough time in contact with the cold to condense out the water. It also allows sufficient airflow to keep the hot side of the module from overheating.

Water collection was a challenge, too. Water always finds a way to leak, and [Ben] came up with a clever case design incorporating a funnel to direct water away. The module is also periodically run in reverse to defrost the cold side heatsink.

The dehumidifier lives in a large tool cabinet with plenty of room for filament rolls and is run by an ESP32-C3 with temperature and humidity sensors, which allowed [Ben] to farm most of the control and monitoring out to ESPHome. The setup seems to work well, keeping the relative humidity inside the cabinet in the low 20s — good enough for PETG and TPU.

It’s an impressively complete build using off-the-shelf parts. For a different approach to solid-state filament drying, check out [Stefan]’s take on the problem.

Reducing Seams In FDM Prints With Scarf Joint Seams

March 11, 2024 by Maya Posch 11 Comments

One unavoidable aspect of FDM 3D printing is that each layer consists out of one or more lines that have a beginning and an end. Where these join up, a seam is formed, which can be very noticeable if the same joint exists on successive layers. Taking a hint from woodworking, a possible solution is now being worked on that involves scarf joints. This research is covered by [Michael Laws] in a recent Teaching Tech video on YouTube, where he also details his own printing attempts with a custom 3D model, and a guide by [psiberfunk/Adam L].

The idea for a scarf joint was pitched practically simultaneously by [vgdh] on the PrusaSlicer GitHub, and [Noisyfox] on the OrcaSlicer GitHub. The basic idea follows the woodworking and metalworking version of a scarf joint, with the overlap between two discrete parts across two heavily tapered ends. As with the woodworking version, the FDM scarf joint is not a silver bullet, and with the under development OrcaSlicer builds a lot of the parameters are still being tweaked to optimize the result.

If it can be made to work, it could mean that scarf joints will soon be coming to an OrcaSlicer and PrusaSlicer release near you. Theoretically it should mean faster prints than with randomized seams as fewer print head adjustments are needed, and it may provide a smoother result. Definitely an interesting development that we hope to see come to fruition.

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EasyThreed K9: The Value In A €72 AliExpress FDM 3D Printer

February 12, 2024 by Maya Posch 27 Comments

The hot end of the EasyThreed K9 is actually pretty nifty. (Credit: [Thomas Sanladerer])

Recently, [Thomas Sanladerer] bought an EasyThreed K9 off AliExpress for a mere €72, netting him an FDM printer with a 10 x 10 x 10 cm build volume. The build plate is unheated, with optional upgrade, and there is no display to interact with the device: just a big multi-function ‘play’ button and five smaller buttons that direct the print head to preset locations above the build plate to allow for build plate leveling using the knobs on each corner. There’s also a ‘home’ button on the back for homing the print head, which pretty much completes the user interface. As the printer comes in a rather small box, the first step is to assemble the parts into something resembling a 3D printer.

What follows is both a mixture of wonder and horror, as the plastic build quality is everything but convincing, while at the same time, the self-contained nature of each of the three axes of the cantilevered design makes for very easy assembly. The print head has a nifty flip-up cover for easy access to the hot end, which makes the best of the anemic 24-watt power supply for the entire printer. A cooling fan with an air duct even provides part cooling, making this print head a contender for the ‘cheap but not terrible’ category. You can check out his full video review below.

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3D Printing A Nifty Sphere Without Supports

November 26, 2023 by Donald Papp 6 Comments

[DaveMakesStuff] demonstrates a great technique for 3D printing a sphere; a troublesome shape for filament-based printers to handle. As a bonus, it uses a minimum of filament. His ideas can be applied to your own designs, but his Giant Spiralized Sphere would also just happen to make a fine ornament this holiday season.

Printing two interlocking parts and using vase mode ensures a support-free print that uses a minimum of filament.

The trick is mainly to print the sphere in two parts, but rather than just split the sphere right down the middle, [Dave] makes two hollow C-shaped sections, like a tennis ball. This structure allows the halves to be printed in vase mode, which minimizes filament use while also printing support-free.

Vase (or spiral) mode prints an object using a single, unbroken line of extruded filament. The resulting object has only one wall and zero infill, but it’s still plenty strong for an ornament. Despite its size, [Dave]’s giant ball uses only 220 grams of filament.

A video (also embedded below) shows the design in better detail. If you’d like to experiment, we’ve previously covered how PETG’s transparency is best preserved when 3D printing by using vase mode, slightly overextruding, and printing at a higher temperature to ensure solid bonding between each layer. Continue reading “3D Printing A Nifty Sphere Without Supports” →

A 3D Printed Grinder For Printed Lens Blanks

November 16, 2023 by Dan Maloney 20 Comments

When one thinks of applications for 3D printing, optical components don’t seem to be a good fit. With the possible exception of Fresnel lenses, FDM printing doesn’t seem up to the job of getting the smooth surfaces and precision dimensions needed to focus light. Resin printing might be a little closer to the mark, but there’s still a long way to go between a printed blank and a finished lens.

That gap is what [Fraens] aims to fill with this homebrew lens grinding machine. It uses the same basic methods used to grind and polish lenses for centuries, only with printed components and lens blanks. The machine itself consists of a motorized chuck for holding the lens blank, plus an articulated arm to hold the polishing tool. The tool arm has an eccentric drive that wobbles the polishing tool back and forth across the blank while it rotates in the chuck. Lens grinding requires a lot of water and abrasive, so a large bowl is provided to catch the swarf and keep the work area clean.

Lens blanks are printed to approximately their finished dimensions using clear resin in an SLA printer. [Fraens] spent a lot of time optimizing the printing geometry to minimize the number of print layers required. He found that a 30° angle between the lens and the resin pool worked best, resulting in the clearest blanks. To polish the rough blanks, a lapping tool is made from polymer modeling clay; after baking it dry, the tool can hold a variety of pads and polishing compounds. From there it’s just a matter of running the blank through a range of abrasives to get the desired final surface.

Are the lenses fantastic? Well, they’re probably not going to make it into fine optical equipment, but they’re a lot better than you might expect. Of course, there’s plenty of room for improvement; better resins might result in clearer blanks, and perhaps degassing the uncured resin under vacuum might help with bubbles. Skipping the printed blanks and going with CNC-machined acrylic might be worth a try, too.

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