How Did Apollo Separate?

May 13, 2026 by 23 Comments

If you’ve watched a Saturn V launch, you’ve probably seen how a large rocket will often jettison a stage on the way up. There are several reasons for this — there is no reason to haul an empty fuel container, for example. However, you can probably imagine how the separation works. You release something — probably explosive bolts — and gravity pulls the old stage away from you as you climb on the next stage’s engines. But what about on the way back? The command module drops the service module before reentry. [Apollo11Space] has a video explaining just how complicated that was to pull off. You can watch it below.

The main problem? The service module has almost everything you need: oxygen, a big engine, fuel, and electrical generation capability. If you’ve ever seen a real command module, they are tiny. Somehow, you need to get the command module prepared to be on its own for the amount of time it takes to land, and get the service module safely away.

Continue reading “How Did Apollo Separate?” →

FreeCAD 1.1 Tutorial, For Beginners Who Like Clear Instructions

May 13, 2026 by 53 Comments

If you’ve been interested in FreeCAD but haven’t known where to start, here’s a wonderful video tutorial for FreeCAD 1.1 by [Deltahedra] aimed squarely at how to model a 3D part from scratch while also following best engineering practices for part design. It focuses on a concise and meaningful workflow that respects your time and doesn’t make assumptions about skill level. It even starts by taking a few moments to explain how to navigate the interface, a courtesy many will appreciate.

FreeCAD can do quite a lot, so a tutorial that focuses on a specific yet broadly-applicable task with a clear context is a great way to narrow the scope into something manageable, and be comprehensive without getting bogged down in minutiae. [Deltahedra] does this by exclusively using the part design workbench, demonstrating what to do to make a part step-by-step, and showing common mistakes that can happen and how to fix them if they occur. Beyond that, it’s left up to the curious hacker to delve for themselves into what else FreeCAD has to offer.

Since 1.1 is (at this writing) the latest stable release, one can also be confident that the tutorial will match the user interface and features one sees on their own screen. After all, it can be frustrating to attempt to follow a tutorial only to find out things are a few versions behind and nothing is where one expects it to be.

Best practices aren’t just fussy rules about how to do things, and [Deltahedra] demonstrates this by showing how certain procedures just plain make more sense when designing shapes. Our own Arya Voronova has also shared best practices for FreeCAD, so check that out for some added perspective. You’ll be wielding FreeCAD in confidence and comfort in no time.

Thanks for the tip, [Vik Olliver]!

Continue reading “FreeCAD 1.1 Tutorial, For Beginners Who Like Clear Instructions” →

Custom Mainboard For PS2 Portable

May 13, 2026 by 7 Comments

As time marches on, the retro gaming community gets more and more access to older systems. This is partially a product of modern computing having much more power to emulate more demanding systems, but also because many in the community have spent more time with their favorite systems. Such is the case for [tschicki] who has spent considerable time and effort reverse engineering the Playstation 2 to come up with this custom mainboard for a handheld version that still uses some of the original chips from the console.

This Playstation 2 handheld console is designed almost completely from the ground up, not just including the impressive main board but also its modernized features, including USB power delivery handled by an RP2040, digital video output, support for modern storage media like SD cards, a customized boot ROM, and upgraded audio. The DualShock 2 controller is also implemented within the handheld, and the case itself is designed to be 3D printed. It’s an impressive effort which preserves the original feel of the console without relying too much on ancient hardware for everything.

Before jumping in to building one yourself, though, [tschicki] cautions that this project is not for the faint of heart, as it requires some specilized tools and a high degree of skill, but for those still wishing to attempt this build all of the instructions are available on the project site. For such a popular console it’s no surprise we’ve seen plenty of other handheld PS2s before, from this one which uses an original PS2 mainboard to this one we featured way back in 2010.

Thanks to [raz] for the tip!

Y-zipper: 3D Printing Flexible–Rigid Transition Mechanism For Rapid And Reversible Assembly

May 13, 2026 by 19 Comments

Along with Velcro, zippers have become an integral part of every day life, being a quick and easy way to usually temporarily join fabric together. Which isn’t to say that you cannot do more with the basic zipper concept, including using them to turn floppy 2D shapes into rigid 3D ones, such as with the Y-zipper concept proposed and demonstrated by [Jiaji Li] et al.

Although not a fully new idea, the Y-zipper is compared with a range of similar mechanisms that do not feature the same abilities, including the standard zipper ease of zipping up, the possibility of having curved geometry and automatic actuation.

Plus there is that the Y-zipper is designed from the start to be 3Dprinted, while still following the same basic pattern of interlocking teeth that the slider mechanism alternately pushes together or pulls apart.

By modifying the basic straight design of the flat strips, the resulting zipped-up form can take on a distinct bend, as well as turn into a coil or a screw. With a demonstrated joint design it is then possible to join multiple Y-zipper rods together, which could make for an interesting alternative to traditional pop-up tent supports, for example.

Also demonstrated is the use of TPU to create compliant bridges, as well as the direct integration of fabric, to show the versatility of the technology. With the used materials (PLA, TPU) the researchers estimate a maximum viable length of about 3 meters before the printed structures begin to disintegrate.

Measure The Earth’s Rotation Victorian Style

May 13, 2026 by 8 Comments

You’ve probably seen a Foucault pendulum in a museum. This Victorian-era science demonstration is named after physicist Léon Foucault and shows how the Earth rotates compared to a pendulum moving in a fixed plane. [RyanCreates] shows you how you can make your own, and it is surprisingly simple.

All you need is a heavy weight like a small mushroom anchor, fishing line, and a swivel — all things you can pick up at any sporting goods store. You’ll need a way to suspend it all, such as an eye hook in the ceiling.

In addition to the mechanical parts, the build calls for a camera to record the results and a lighter or other source of flame. The reason? To release the pendulum, you burn a thread that prevents it from swinging. This allows for a clean release with no sideways force.

The amount of your rotation depends on your latitude. At 33 degrees north, for example, you can expect 360*sin(33)/24 or 8.17 degrees per hour of rotation. [Ryan] measured a somewhat larger number, which was probably due to an error source, especially since he is measuring the angle using captured camera frames in Photoshop. That has to introduce some error, and small pendulums like this are incredibly sensitive to errors.

If you try it and find the source of the error, we’re sure [Ryan] would love to hear from you. Museum pieces are typically much larger, have ultra-low-friction pivots, and use electromagnets to keep the pendulum moving since, after all, even a Foucault pendulum can’t run forever.

VTech Toy Becomes PinkPad, The DIY Linux Laptop

May 13, 2026 by 2 Comments

Originally envisioned as a simple DIY laptop project, [kati]’s PinkPad V1 ended up being considerably more involved than expected. But the end result is a perfectly usable, stunningly pink, and remarkably sturdy portable laptop that looks nothing like a hack job.

Originally a VTech toy, the PinkPad is a perfectly functional DIY laptop.

The PinkPad V1 started as a toy laptop for toddlers, repurposed into a DIY laptop running Linux while keeping the original clamshell design and cute aesthetic. As [kati] herself points out, while it may not seem particularly difficult to yank out a toy’s insides and stuff it with a Raspberry Pi, most of the real challenges were related to actually getting all the necessary parts and connectors and wiring to actually fit in a useful way. As anyone with experience in building something knows, working around existing enclosures or hardware almost always brings unexpected challenges.

The original toy laptop? Produced by none other than VTech, whose products have been hacked to create things like a punch card-reading cyberdeck and Z80 hacking station. Our own [Tom Nardi] has also shared his fondness for these devices in several teardowns over the years.

In the end, [kati]’s PinkPad ended up sporting a mini keyboard (whose black keys were turned pink with a little nail polish) and a 5 inch touchscreen LCD. Combined with a rechargeable power supply, it provides all the comforts of an Arch Linux ARM mini laptop.

Thanks [alex] for the tip!

Build The CPU, Then Build The Calculator

May 13, 2026 by 18 Comments

It’s possible that among Hackaday readers are the largest community of people who have designed their own CPU in the world. We have featured many here, but it’s possible that not so many of them have gone on to power an everyday project. Step forward [Baltazar Studios] then, with a scientific calculator sporting a self-designed CPU on an FPGA.

The calculator itself is nice enough, with a smart 3D printed case, an OLED display which almost evokes a VFD, and very well made buttons. But it’s the CPU which is of most interest, because while it follows a conventional Harvard architecture with a 12-bit instruction set, it works with 4-bit nibbles. This choice follows one used by HP in their calculator designs, seemingly because it can be optimised for the binary coded decimal which the calculator uses.

With calculators being yet another app on our spartphones or comnputers, there seems to be less use of calculators outside of education in 2026. But if you are a calculator user there’s nothing like a calculator you made yourself, and with a CPU of your own design it has few equals. We like this project almost as much as we like the Flapulator!