Building A Gifford-McMahon Cryocooler With 3D-Printed Parts

June 6, 2026 by Maya Posch 12 Comments

Although cryocoolers are capable of pretty impressive cooling, for many of them the underlying working principle is simple enough that you do not need any special skills or a big budget to make your own version. Take the Gifford-McMahon cryocooler for example, which works using nothing more than some kind of coolant gas and a piston in a cylinder that you can even 3D print, as demonstrated by [Hyperspace Pirate] in a recent video.

The lowest temperature reached across the two prototypes was only -84°C, but this was mostly due to some sub-optimal design choices, such as the use of regular air and a clear acrylic tube to get a good glimpse at the inner workings. The trickiest part of this type of cryocooler is probably that you need to move the piston containing the regenerator between both ends of the cylinder to get a cool and a hot side.

That particular problem was solved by using magnets to move the piston externally, which worked beautifully until the problem of using regular compressed air from the shop compressor caused massive ice formation that jammed up the piston. Obviously this was not an unexpected issue, and for the next step the coolant gas will be replaced by helium, as making that gas freeze up requires quite a bit more effort.

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Stratasys Vs Bambu Lab: Industrial Vs Consumer ABS Showdown

June 6, 2026 by Maya Posch 16 Comments

The test parts being printed on the Stratasys Fortus 450mc. (Credit: My Tech Fun, YouTube)

Professional Stratasys FDM printers demand a pretty hefty price premium over your typical hobbyist-level machine, with the gold-plating continuing even with the special filament cartridges that you buy for some of their printers.

This raises the question of in how far this eye-watering price tag is justified, and how much is just you paying for support and the brand name. After acquiring a spool of Stratasys ABS filament via a US viewer, [Dr. Igor Gaspar] set to work to try and answer this question.

The viewer had already liberated the spool of ABS+ P430 filament from its cartridge, making it easy to use that directly with the Bambu Lab FDM printer.

To make it a fair comparison, [Igor] also needed to have a sample printed on a real Stratasys printer, for which he used a local company’s services. An interesting sidenote here is that the US viewer’s company moved away from Stratasys to Bambu Lab printers.

[Igor] was able to see his test parts being printed on the Stratasys printer, as said company is in the same city. This showed him that it took 14 hours to print the parts versus 3.5 hours on the Bambu Lab printer, suggesting that his worries about the right printing parameters for the Stratasys filament were warranted. Sussing those out was thus paramount for a fair comparison and warranted some test prints.

From a sheer aesthetic point of view the Stratasys-printed parts looked much cleaner, and their dimensional accuracy was also significantly better due to the slicer adjusting for this. Between the used Stratasys M30 and Bambu Lab ABS filaments there’s no clear winner, with both trading blows. Amusingly enough, the older Stratasys ABS type in the form of the ABS+ P430 filament performed the best of all when printed on the Bambu Lab printer at its preferred temperature setting.

Moral of the story is thus that – unless you really want to pay for that service contract – to loot old Stratasys ABS spool cartridges and use them in your hobbyist FDM printer. As [Igor] says in the conclusion, the nicer looks is probably due to them printing very thin layers, much finer than the 0.2 mm layers he used. This would also match the much longer print time and is thus something we can replicate on any FDM printer with a temperature-controlled printing environment.

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Using Brand New NiMH Cells After Sitting 12 Years Unused

June 5, 2026 by Maya Posch 26 Comments

You know your batteries are old when their labels have faded. (Credit: DiodeGoneWild, YouTube)

After finding a pack of NiMH rechargeable cells that had never been used since buying them in 2014, [DiodeGoneWild] decided to test whether they could be tossed or not. After previously testing different brand cells that had gone high internal resistance after only about five years, he wasn’t expecting much. Amazingly, the batteries not only recovered, but seems to be not that much worse off for wear.

Three of the four precharged cells still held some voltage and happily charged back up to their rated 2,000 mAh capacity basically with the first cycle. One of them read 0V initially, but was revived using the typical manual charging approach involving a bench power supply. After a few charge-discharge cycles only the deep discharged cell showed some noticeable degradation with slightly reduced capacity, but all of them read healthy internal resistance values.

What this mostly shows is that not all NiMH cells are made the same, with the Tronic ones that previously failed after a few years doing much worse than these Activ Energy cells which are apparently sold primarily at Aldi stores. Overall NiMH is a pretty robust battery chemistry, so it’s always worth it to try reviving a cell before tossing it.

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Investigating The S3 Virge’s Reputation As A 3D Decelerator Card

June 5, 2026 by Maya Posch 16 Comments

The special 512x384 mode with S3 card installed. (Credit: Bits und Bolts, YouTube) — The special 512×384 mode with S3 card installed. (Credit: Bits und Bolts, YouTube)

Back in 1996 the 3D gaming market on PC was beginning to heat up, with hot new titles like Tomb Raider coming out that year and requiring much more graphics power than what was needed for old titles like Doom and Duke Nukem 3D to experience good graphics. Thus you had to pick some kind of 3D accelerator card to buy. Here a common joke was that of the available options, the S3 Virge GPU was so bad that it was actually worse than running in software rendering, but was this true? Cue [Bits und Bolts]’s investigation to finally put this myth to rest.

On software rendering mode a zippy Pentium 166 would struggle to render at 640×480 resolution, so if you wanted more than 320×240, or really knock down graphical fidelity, you had to get that 3D accelerator card. After combining a P166 with an S3 Virge/DX – a minor update to the original Virge – the Tomb Raider game was first compared while running in 512×384 resolution, which the game offers you with an S3 card installed along with bilinear filtering.

After hitting a capped 30 FPS on that first test, 640×480 was tried and hit a solid 15 FPS with bilinear filtering enabled, but the conclusion is basically that the special 512×384 resolution mode is pretty good. Perhaps the main causes of the myth was the wide variability in quality of the various GPUs using the S3 Virge chip, as well as trying to run at anything other than this special resolution which appears to target the card’s strengths.

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Over-Engineering An FDM Spool Holder From Prusa Mk4S Remains

June 5, 2026 by Maya Posch 3 Comments

Unlike resin printers where you generally just pour the fresh resin into the easily accessible vat, FDM printers need to squirrel away at least one spool and its requisite holder somewhere. For bed slingers this generally means a top-mounted spool holder, while for CoreXY enclosed printers they can appear on the sides, top or – inexplicably – on the back. While a side-mounted spool is often convenient, access to the side can still be blocked, in which case you do what [3D Maker Noob] did and over-engineer a fancy top-mounted spool holder.

The problem started after converting a Prusa Mk4S to a Core One using the conversion kit, which changes the position of the spool, forcing him to work around not having access to the right side of the machine where the default position is. After a first version using many of the left-over parts of the original Mk4S to create a fancy box-shaped spool holder, he proceeded to upgrade it as detailed in the video. All project files and instructions are available on Printables.

The result is a box you stack on top of the printer somewhat like a multi-spool box, just flatter and with a flippy lid on the front from which a rail slides out with the magnetically attached spool holder. A spool holder which you naturally can further customize to fit different spools. Even if over-engineered, you can’t deny that it would fit in confined spaces and looks pretty good while doing its job.

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Using Windows 11 On An LGA 775 PC With AGP Videocard

June 5, 2026 by Maya Posch 15 Comments

Although the thought of installing a modern operating system like Windows 11 on something as archaic as a Core 2 Quad Q6600 Intel CPU may seem ridiculous, it being the flagship CPU of the time means that it still chews up low-end Celeron systems that are on the supported hardware list like the N4020. Hence [Omores] commencing on this latest adventure, with the snag being that the chosen mainboard features an AGP bus that Windows 11 no longer supports.

A GPU box from the related HD 4670 PCIe card, not the used HD 4650 AGP card with 1 GB of DDR2. (Credit: Omores, YouTube) — A GPU box from the related HD 4670 PCIe card, not the used HD 4650 AGP card with 1 GB of DDR2.

This system is intended to multi-boot a range of Windows OSes starting with Windows 98, while also playing nice with DOS and even Windows 11. In addition to the quad-core, 2.4 GHz Q6600 there’s also an amazing 3 GB of DDR1 RAM in the system.

The mainboard is the 2003-era Asrock 865PE, with the GPU being the highest-end GPU that still came in AGP flavor: the Radeon HD 4650 from 2009. Since the sole reason that Windows 11 doesn’t support AGP any more is due to the supporting files not being included with Windows 11, hence you can track it down on a Windows 10 1507 release install – such as the Intel AGP440.sys driver here – and install them with some file editing.

Since Windows 11 still supports the WDDM driver model from Windows Vista and 7 you can then install the Catalyst drivers from 2012 and be up and running. You only get 1 GB of VRAM for this card, but you probably don’t need much more on this level of hardware.

One major stumbling block remains, however, as Windows 11 24H2 enforces SSE4.2 instructions which the CPU doesn’t support. Ergo 23H2 is the newest Windows 11 version that can run on this system, with only the Education and Enterprise still receiving security updates, making it a bit of a pyrrhic victory, especially as Windows 7 benchmarks a fair bit faster on the same hardware.

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Using Electrolysis For More Than Just Generating Hydrogen

June 5, 2026 by Maya Posch 6 Comments

When the topic of ‘electrolysis’ is mentioned, people typically think of just splitting plain old dihydrogen monoxide (hydric acid: H₂O) into its constituent atoms, but this barely scratches the surface of what is going on during electrolysis. Once you understand the full picture it also becomes obvious how electrolysis can be used for other tasks, including metal refining, flow batteries and more, as covered in a recent video by [NightHawkInLight].

On a fundamental level electrolysis is what it says on the tin: a way to lyse (i.e. split apart) using electrons, which is what the anode and cathode provide or remove. This can be used to break down the bonds between hydrogen and oxygen, but also those of iron ore, like Fe₃O₄. Stripping the oxygen from the iron atoms is commonly done in a reduction process using the CO from coke or hydrogen,

Setup for electrolysing iron ore. (Credit: NightHawkInLight, YouTube) — Setup for electrolysing iron ore.

By instead dissolving the iron ore in acid, electrolysis can then be used to separate the two. In the example, the acid is created by one side of the electrolytic cell, with both electrodes separated by an ion-exchange membrane barrier that prevents the chemical processes on each side of the cell to affect the other side while still enabling the cell to work. How to make these membranes is also demonstrated in the video.

Through a careful arrangement of these membranes and the electrodes, you can guide which reactions can occur where, and which – negative or positively charged – ion can pass through which membrane, giving a lot of control. It can also be used to prevent undesirable reactions from happening, such as in this case the generating of chlorine gas from the NaCl being lysed.

Acidity indicator dye is used to show in great detail how the cell works, including its preparation of getting the acidity just right before the crushed iron ore is mixed with some of the generated acid and the resulting liquid added to the cell. Following this you get a closed-loop chemical process to which only fresh iron ore slush has to be added and electrodes swapped out for fresh ones as the build-up of iron becomes sufficiently thick. In addition to supplying the cell with electricity, naturally, though you can even invert the cell and use it as a chemical battery akin to a lead-acid one if that’s more your thing.

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