PVA Filament: Not Always What It Seems

June 20, 2025 by Maya Posch 6 Comments

PVA filament with a core. (Credit: Lost In Tech)

PVA filament is an interesting filament type, for the reason that while it can be printed with any FDM printer, it supposedly readily dissolves in water, which is also the reason why PVA glue sticks are so popular when doing crafts and arts with young children. This property would make PVA filament ideal for printing supports if your printer can handle two different materials at the same time. So surely you can just pick any old PVA filament spool and get to printing, right? As [Lost in Tech] found out, this is not quite the case.

As an aside, watching PVA supports dissolve in water set to classical music (Bach’s Air from Orchestral Suite No. 3) is quite a pleasant vibe. After thus watching the various PVA prints dissolve for a while, we are left to analyze the results. The first interesting finding was that not every PVA filament dissolved the same way, or even fully.

The first gotcha is that PVA can stand for polyvinyl acetate (the glue stick) or polyvinyl alcohol (a thickener and stabilizer) , with the ‘PVA’ filament datasheets for each respective filament showing various combinations of both types of PVA. This results in wildly different properties per filament, both in terms of Shore hardness, their printability, as well as their ability to dissolve in water. Some of the filament types (Yousu, Reprapper) also have an outer layer and inner core for some reason.

Ultimately the message appears to be that ‘PVA’ filament requires a fair bit of research to have any chance of having a relatively trouble-free printing experience.

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Build Your Own Telescope The Modern Way

June 19, 2025 by Al Williams 37 Comments

When we were kids, it was a rite of passage to read the newly arrived Edmund catalog and dream of building our own telescope. One of our friends lived near a University, and they even had a summer program that would help you measure your mirrors and ensure you had a successful build. But most of us never ground mirrors from glass blanks and did all the other arcane steps required to make a working telescope. However, [La3emedimension] wants to tempt us again with a 3D-printable telescope kit.

Before you fire up the 3D printer, be aware that PLA is not recommended, and, of course, you are going to need some extra parts. There is supposed to be a README with a bill of parts, but we didn’t see it. However, there is a support page in French and a Discord server, so we have no doubt it can be found.

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A Prunt 3D printer control board is shown mounted in a 3D printer, just behind a power supply, in the center of the image.

Keeping Snap And Crackle Under Control With Prunt Printer Firmware

June 18, 2025 by Aaron Beckendorf 27 Comments

For quite some time now, Marlin has been the firmware of choice for any kind of custom 3D printer, with only Klipper offering some serious competition in the open-source world. [Liam Powell] aims to introduce some more variety with the development of Prunt, a 3D printer control board and firmware stack.

Smooth motion control is Prunt’s biggest advantage: Klipper and Marlin use trapezoidal (three-phase) motion profiles, which aim for acceleration changes with physically impossible rapidity, leading to vibrations and ringing on prints. By contrast, Prunt uses a more physically realistic 31-phase motion profile. This lets the user independently adjust velocity, acceleration, jerk, snap, and crackle (the increasingly higher-order derivatives of position with respect to time) to reduce vibration and create smoother prints. To avoid sharp accelerations, Prunt can also turn corners into 15-degree Bézier curves.

The focus on smooth motion isn’t just a software feature; the Prunt control board uses hardware timers to control step generation, rather than the CPU. This avoids the timing issues which Klipper sometimes faces, and avoids slowing other parts of the program down. The board also seems to have a particular focus on avoiding electrical damage. It can detect short circuits in the heaters, thermistors, fans, and endstops, and can cut power and give the user a warning when one occurs. If the board somehow experiences a serious electrical fault, the USB port is isolated to prevent damage to the host computer. The firmware’s source is available on GitHub.

If you’re more interested in well-established programs, we’ve given a quick introduction to Klipper in the past. We’ve also seen people develop their own firmware for the Bambu Lab X1.

Expanding Racks In The Spirit Of The Hoberman Sphere

June 16, 2025 by John Elliot V 7 Comments

If you’re a mechanical engineering wonk, you might appreciate this latest video from [Henry Segerman] wherein he demonstrates his various expanding racks.

[Henry] explains how the basic “double-rack” unit can be combined to make more complex structures. These structures are similar in spirit to the Hoberman sphere, which is a compact structure that can be expanded to fill a large space.

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Upgrade Your Filament Dryer With A Swiveling Filament Port

June 15, 2025 by Maya Posch 3 Comments

Many FDM filament dryers have a port through which you can guide the filament. This handy feature allows you to print from the spool without removing it from the dryer, saving time and limiting exposure to (moist) air. Unfortunately, these exit ports aren’t always thought out very well, mostly in terms of the angle with the spool as it unrolls. The resulting highly oblique orientation means a lot of friction of the filament on the side of the port. This issue is addressed in a recent [Teaching Tech] video, with a simple, low-cost solution.

The basic idea is to have a swiveling port, inspired by a spherical bearing. The design shown in the video uses a PC4-M6 pneumatic connector to pass the PTFE tube. Connector choice is critical here, as many PC4-M6 pneumatic connectors won’t accommodate the PTFE. As a fallback, you can drill out a connector to enable this.

Once the connector is sorted, you need a 13 mm (~0.5″) step drill bit to widen the opening in the filament dryer. This ready-to-print version has 10 degrees of freedom in any direction, but you can adapt it to fit your needs. With this mod installed, the angle with which the filament enters the port should remain as close to zero as possible, preventing both friction and damage to the port and filament.

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RC rover/car with red and yellow-sided wheels. Electronics are visible on top of vehicle.

An RC Car Driven With Old 3D Printer Motors

June 15, 2025 by Ian Bos 5 Comments

With the newer generation of quick and reliable 3D printers, we find ourselves with the old collecting dust and cobwebs. You might pull it out for an emergency print, that is if it still works… In the scenario of an eternally resting printer (or ones not worth reviving), trying to give new life to the functional parts is a great idea. This is exactly what [MarkMakies] did with a simple RC rover design from an old Makerbot Replicator clone.

Using a stepper motor to directly drive each wheel, this rover proves its ability to handle a variety of terrain types. Stepper motors are far from the most common way to drive an RC vehicle, but they can certainly give enough power. Controlling these motors is done from a custom protoboard, allowing the use of RC control. Securing all these parts together only requires a couple of 3D printed parts and the rods used to print them. Throw in a drill battery for power, and you can take it nearly anywhere!

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Threaded Insert Press Is 100% 3D Printed

June 11, 2025 by Tyler August 12 Comments

Sometimes, when making a 3D printed object, plastic just isn’t enough. Probably the most common addition to our prints is the ubiquitous brass threaded inset, which has proven its worth time and again over the years in providing a secure screw attachment point with less hassle than a captive nut. Of course to insert these bits of machined brass, you need to press them in, and unless you’ve got a very good hand with a soldering iron it’s usually a good idea to use a press of some sort. [TimNummy] shows us that, ironically enough, making such a press is perfectly doable using only printed parts. Well, save for the soldering iron, of course.

He calls it the Superserter. Not only is it 100% printed plastic, but the entire design fits on a single 256 mm by 256 mm bed. In his case it was done on the Bambulab X1C, but it’s a common enough print bed size and can be printed without any supports. It’s even sized to fit the popular Gridfinity standard for a neat and tidy desk and handy bin placement for the inserts.

[TimNummy] clearly spent some time thinking about design for 3D printed manufacturing in order to create an assembly that does not need linear rails, sliders, or bearings as other press projects often do. The ironic thing is that if that same amount of effort went into other designs, it might eliminate the need for threaded inserts entirely.

If you haven’t delved into the world of threaded inserts, we put up a how-to-guide a few years ago. If you’re wondering if you can get away with just printing threads, the answer is “maybe”– we highlighted a video comparing printed threads with different inserts a while back to get you started thinking about the design limitations there.

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