Testing Various Ways To Waterproof FDM Printed Parts

May 30, 2026 by Maya Posch 2 Comments

Along with layer lines, FDM printers are notorious for being neither air- nor water-tight due to the countless very small gaps between the layers. This is very unfortunate if you are trying to FDM print something that should keep water either inside or outside. Although a variety of potential solutions exist, it’s hard to easily compare them. Correspondingly [Half-Baked-Research] decided that the best approach here was to just try everything and pit them against each other.

These solutions include various coatings either in- or outside the part, as well as the foam solution that he tried previously joined by a number of community-suggested alternatives that should not get waterlogged. To properly test them, the water pressure at a depth of about 10 meters would be good enough, but rather than find a really deep swimming pool or try his luck at nearby bodies of water, compressed air was used to ramp up the pressure of a what is basically a big bucket of water.

For the pressure chamber a Vevor vacuum chamber was modified to contain the 1 bar (103 kPa) of pressure, which was a fair bit of work and required a CNCed metal top plate. Among the printed and treated samples were also a couple of wild cards: a PETG cube with a TPU printed cover, a PU molded part and PETG with thicker walls.

Along with the long soak, percussive testing was also performed to see how it’d affect the water intrusion resistance. After all that, there were three winners: internal epoxy coating and two types of internal PU coating, though epoxy held up the best after repeated abuse. PU rubber also got a thumbs-up if you don’t need as high a pressure resistance but are more concerned with resisting physical abuse.

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Putting Version 7.1 Of The Direct Granules FDM Extruder Through Its Paces

May 23, 2026 by Maya Posch 11 Comments

Whether you’re using granules or filament, FDM printing relies heavily on a consistent flowrate of the extruder. This is also the challenge with [HomoFaciens]’s direct granule extruder. Version 7.1 here refines some parameters before being put through a number of printing tests to see how close it comes to something you’d want to use for production.

There’s also an accompanying blog post, on which the project files can be found for those who are playing along at home.

A big part of this V7.1 change was to simplify the design for manufacturing, removing the brass insert of V7.0, instead requiring some manual labor using a drill bit and a hand reamer to get the inside of the extruder tube just right.

The section with the heating element was also extended, though this didn’t have as much of an effect as expected. During testing the overall results were actually pretty good, with the extruder able to keep up with bridging tests while the feared air bubbles from air intruding into the tube remained absent.

On the Prusa Mk4 FDM printer, there are some definite limitations on testing features like input shaping resulting in wavy patterns in some rest prints, but for upcoming tests a different FDM printer will be used which should more clearly show the potential of this extruder design.

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Direct FDM Printing With Granules

May 6, 2026 by Maya Posch 16 Comments

The idea of FDM 3D printing using granules rather than filament is an appealing one: rather than having to wrangle spools of filament that need to adhere to strict dimensions and cannot be too flexible, you can instead just keep topping up a big hopper with fresh granules. This is what [HomoFaciens] has been tinkering with for a while now, with their Direct Granules Extruder V7.0 showing significant improvements.

There’s also an accompanying article, with details of previous granule extruder attempts detailed on the same site. Many of the improvements here focus on making sure the granules melt properly before they reach the end of the extruder, with the auger screw helping to push things along. While this seems straightforward, there are many details to get right, with the previous v6.2 version having issues like the hot plastic backing up into the cold section and clogging things up.

For the test bench a Prusa Mk4 FDM printer is used, with the standard extruder swapped for the experimental extruder. On the extruder the cold, top part is water cooled to ensure it stays cold, with each turn of the wood-screw-turned-auger providing the right extrusion speed. As can be seen with the print tests, the results look pretty good despite the extruder not having been tuned yet.

If you want to give it a shot yourself, the article page provides files for download.

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Testing A Continuous Printing Mod For The Bambu Lab A1 Mini

January 16, 2026 by Maya Posch 9 Comments

There are a few types of continuous 3D printing with FDM printers, with a conveyer belt and automatic build plate swapping the most common types. The advantage of build plate swapping is that it automates the bit where normally a human would have to come in to remove finished parts from the build plate. A recent entry here is the Chitu PlateCycler C1M which the [Aurora Tech] YouTube channel had over for a review. This kit bolts onto the Bambu Lab A1 Mini FDM printer and comes with four extra PEI build plates for a not unreasonable $79 (€69).

As also noted in the review video, this is effectively a clone of the original swapmod A1m kit, but a big difference is that the Chitu kit comes with all of the parts and doesn’t require you to print anything yourself.

The different plates are prepared using a special tool that inserts G-code between the plate changes. Moving the bed in a specific way triggers the switch that lifts the finished plate off the magnetic bed by the plastic grip on the plate and loads a fresh plate from the stack. Here it was found that a small tolerance issue prevented the last plate from being used, but some sandpaper fixed this. Other than that it was a fairly painless experience, and for e.g. multi-color prints with separated colors – as demonstrated – it would seem to be a great way to churn out the entire model without manual intervention or a lot of wasted filament.

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FibreSeeker 3: Continuous Carbon Fiber Vs Chopped CF

December 25, 2025 by Maya Posch 8 Comments

Although you can purchase many types of FDM filaments containing ‘carbon fiber’ these days, they are in no way related to the carbon fiber (CF) composite materials used for rocket hulls and light-weight bicycles. This is because the latter use continuous fibers, often in weaved CF mats, whereas the FDM filaments just use small, chopped, fragments of CF. Obviously this will not result in the same outcome, which makes it interesting that a company called Fibre Seek is now running a KickStarter for a very affordable co-extrusion FDM printer that can add continuous CF to any part. They also sent a few test parts to [Dr. Igor Gaspar] for testing against regular FDM CF prints.

It should be noted here that continuous CF with FDM is not new, as Markforged already does something similar, though at a ‘Contact us for a price quote’ level. The advantage of the Fibre Seek solution is then the co-extrusion that would make printing with continuous CF much more flexible and affordable. Based on the (sponsored) [CNC Kitchen] video of a few weeks ago at a tradeshow, the FibreSeeker 3 printer is effectively a standard CoreXY FDM printer, with the special co-extrusion dual print head that allows for CF to be coated with the target thermoplastic before being printed as normal.

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On The Benefits Of Filling 3D Prints With Spray Foam

November 29, 2025 by Maya Posch 43 Comments

Closed-cell self-expanding foam (spray foam) is an amazing material that sees common use in construction. But one application that we hadn’t heard of before was using it to fill the internal voids of 3D printed objects. As argued by [Alex] in a half-baked-research YouTube video, this foam could be very helpful with making sure that printed boats keep floating and water stays out of sensitive electronic bits.

It’s pretty common knowledge by now that 3D printed objects from FDM printers aren’t really watertight. Due to the way that these printers work, there’s plenty of opportunity for small gaps and voids between layers to permit moisture to seep through. This is where the use of this self-expanding foam comes into play, as it’s guaranteed to be watertight. In addition, [Alex] also tests how this affects the strength of the print and using its insulating properties.

The test prints are designed with the requisite port through which the spray foam is injected as well as pressure relief holes. After a 24 hour curing period the excess foam is trimmed. Early testing showed that in order for the foam to cure well inside the part, it needed to be first flushed with water to provide the moisture necessary for the chemical reaction. It’s also essential to have sufficient pressure relief holes, especially for the larger parts, as the expanding foam can cause structural failure.

As for the results, in terms of waterproofing there was some water absorption, likely in the PETG part. But after 28 hours of submerging none of the sample cubes filled up with water. The samples did not get any stronger tensile-wise, but the compression test showed a 25 – 70% increase in resistance to buckling, which is quite significant.

Finally, after tossing some ice cubes into a plain FDM printed box and one filled with foam, it took less than six hours for the ice to melt, compared to the spray foam insulated box which took just under eight hours.

This seems to suggest that adding some of this self-expanding foam to your 3D printed part makes a lot of sense if you want to keep water out, add more compressive strength, or would like to add thermal insulation beyond what FDM infill patterns can provide.

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Does It Make Sense To Upgrade A Prusa MK4S To A Core One?

August 30, 2025 by Maya Posch 7 Comments

One of the interesting things about Prusa’s FDM 3D printers is the availability of official upgrade kits, which allow you to combine bits off an older machine with those of the target machine to ideally save some money and not have an old machine gathering dust after the upgrade. While for a bedslinger-to-bedslinger upgrade this can make a lot of sense, the bedslinger to CoreXY Core One upgrade path is a bit more drastic. Recently the [Aurora Tech] channel had a look at which upgrade path makes the most sense, and in which scenario.

A big part of the comparison is the time and money spent compared to the print result, as you have effectively four options. Either you stick with the MK4S, get the DIY Core One (~8 hours of assembly time), get the pre-assembled Core One (more $$), or get the upgrade kit (also ~8 hours). There’s also the fifth option of getting the enclosure for the MK4S, but it costs about as much as the upgrade kit, so that doesn’t make a lot of logical sense.

In terms of print quality, it’s undeniable that the CoreXY motion system provides better results, with less ringing and better quality with tall prints, but unless you’re printing more than basic PLA and PETG, or care a lot about the faster print speeds of the CoreXY machine with large prints, the fully enclosed Core One is a bit overkill and sticking with the bedslinger may be the better choice.

The long and short of it is that you have look at each option and consider what works best for your needs and your wallet.

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