Tool Hacks

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A camera-based microscope is on a stand, looking down towards a slide which is held on a plastic stage. The stage is held in place by three pairs of brass rods, which run to red plastic cranks mounted to three stepper motors. On the opposite side of each crank from the connecting rod is a semicircular array of magnets.

Designing An Open Source Micro-Manipulator

September 4, 2025 by 21 Comments

When you think about highly-precise actuators, stepper motors probably aren’t the first device that comes to mind. However, as [Diffraction Limited]’s sub-micron capable micro-manipulator shows, they can reach extremely fine precision when paired with external feedback.

The micro-manipulator is made of a mobile platform supported by three pairs of parallel linkages, each linkage actuated by a crank mounted on a stepper motor. Rather than attaching to the structure with the more common flexures, these linkages swivel on ball joints. To minimize the effects of friction, the linkage bars are very long compared to the balls, and the wide range of allowed angles lets the manipulator’s stage move 23 mm in each direction.

To have precision as well as range, the stepper motors needed closed-loop control, which a magnetic rotary encoder provides. The encoder can divide a single rotation of a magnet into 100,000 steps, but this wasn’t enough for [Diffraction Limited]; to increase its resolution, he attached an array of alternating-polarity magnets to the rotor and positioned the magnetic encoder near these. As the rotor turns, the encoder’s local magnetic field rotates rapidly, creating a kind of magnetic gear.

A Raspberry Pi Pico 2 and three motor drivers control this creation; even here, the attention to detail is impressive. The motor drivers couldn’t have internal charge pumps or clocked logic units, since these introduce tiny timing errors and motion jitter. The carrier circuit board is double-sided and uses through-hole components for ease of replication; in a nice touch, the lower silkscreen displays pin numbers.

To test the manipulator’s capabilities, [Diffraction Limited] used it to position a chip die under a microscope. To test its accuracy and repeatability, he traced the path a slicer generated for the first layer of a Benchy, vastly scaled-down, with the manipulator. When run slowly to reduce thermal drift, it could trace a Benchy within a 20-micrometer square, and had a resolution of about 50 nanometers.

He’s already used the micro-manipulator to couple an optical fiber with a laser, but [Diffraction Limited] has some other uses in mind, including maskless lithography (perhaps putting the stepper in “wafer stepper”), electrochemical 3D printing, focus stacking, and micromachining. For another promising take on small-scale manufacturing, check out the RepRapMicron.

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Applying Thermal Lining To Rocket Tubes Requires A Monstrous DIY Spin-caster

September 2, 2025 by 18 Comments

[BPS.space] takes model rocketry seriously, and their rockets tend to get bigger and bigger. If there’s one thing that comes with the territory in DIY rocketry, it’s the constant need to solve new problems.

Coating the inside of a tube evenly with a thick, goopy layer before it cures isn’t easy.

One such problem is how to coat the inside of a rocket motor tube with a thermal liner, and their solution is a machine they made and called the Limb Remover 6000 on account of its ability to spin an 18 kg metal tube at up to 1,000 rpm which is certainly enough to, well, you know.

One problem is that the mixture for the thermal liner is extremely thick and goopy, and doesn’t pour very well. To get an even layer inside a tube requires spin-casting, which is a process of putting the goop inside, then spinning the tube at high speed to evenly distribute the goop before it cures. While conceptually straightforward, this particular spin-casting job has a few troublesome difficulties.

For one thing, the uncured thermal liner is so thick and flows so poorly that it can’t simply be poured in to let the spinning do all the work of spreading it out. It needs to be distributed as evenly as possible up front, and [BPS.space] achieves that with what is essentially a giant syringe that is moved the length of the tube while extruding the uncured liner while the clock is ticking. If that sounds like a cumbersome job, that’s because it is.

The first attempt ended up scrapped but helped identify a number of shortcomings. After making various improvements the second went much better and was successfully tested with a 12 second burn that left the tube not only un-melted, but cool enough to briefly touch after a few minutes. There are still improvements to be made, but overall it’s one less problem to solve.

We’re always happy to see progress from [BPS.space], especially milestones like successfully (and propulsively) landing a model rocket, and we look forward to many more.

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Checking Out A TV Pattern Generator From 1981

September 2, 2025 by 12 Comments

The picture on a TV set used to be the combined product of multiple analog systems, and since TVs had no internal diagnostics, the only way to know things were adjusted properly was to see for yourself. While many people were more or less satisfied if their TV picture was reasonably recognizable and clear, meaningful diagnostic work or calibration required specialized tools. [Thomas Scherrer] provides a close look at one such tool, the Philips PM 5519 GX Color TV Pattern Generator from 1981.

This Casio handheld TV even picked up the test pattern once the cable was disconnected, the pattern generator acting like a miniature TV station.

The Philips PM 5519 was a serious piece of professional equipment for its time, and [Thomas] walks through how the unit works and even opens it up for a peek inside, before hooking it up to both an oscilloscope and a TV in order to demonstrate the different functions.

Tools like this were important because they could provide known-good test patterns that were useful not just for troubleshooting and repair, but also for tasks like fine-tuning TV settings, or verifying the quality of broadcast signals. Because TVs were complex analog systems, these different test patterns would help troubleshoot and isolate problems by revealing what a TV did (and didn’t) have trouble reproducing.

As mentioned, televisions at the time had no self-diagnostics nor any means of producing test patterns of their own, so a way to produce known-good reference patterns was deeply important.

TV stations used to broadcast test patterns after the day’s programming was at an end, and some dedicated folks have even reproduced the hardware that generated these patterns from scratch.

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Watch Bondo Putty Get Sprayed Onto 3D Prints

August 31, 2025 by 18 Comments

3D prints destined for presentation need smooth surfaces, and that usually means sanding. [Uncle Jessy] came across an idea he decided to try out for himself: spraying Bondo spot putty onto a 3D print. Bondo spot putty comes from a tube, cures quickly, and sands smoothly. It’s commonly used to hide defects and give 3D prints a great finish. Could spraying liquified Bondo putty onto a 3D print save time, or act as a cheat code for hiding layer lines? [Uncle Jessy] decided to find out.

Gaps and larger flaws still need to be filled by hand, but spray application seems to be a big time saver if nothing else.

The first step is to turn the distinctive red putty into something that can be sprayed through a cheap, ten dollar airbrush. That part was as easy as squeezing putty into a cup and mixing in acetone in that-looks-about-right proportions. A little test spray showed everything working as expected, so [Uncle Jessy] used an iron man mask (smooth surfaces on the outside, textured inside) for a trial run.

Spraying the liquified Bondo putty looks about as easy as spraying paint. The distinctive red makes it easy to see coverage, and it cures very rapidly. It’s super easy to quickly give an object an even coating — even in textured and uneven spots — which is an advantage all on its own. To get a truly smooth surface one still needs to do some sanding, but the application itself looks super easy.

Is it worth doing? [Uncle Jessy] says it depends. First of all, aerosolizing Bondo requires attention to be paid to safety. There’s also a fair bit of setup involved (and a bit of mess) so it might not be worth the hassle for small pieces, but for larger objects it seems like a huge time saver. It certainly seems to cover layer lines nicely, but one is still left with a Bondo-coated object in the end that might require additional sanding, so it’s not necessarily a cheat code for a finished product.

If you think the procedure might be useful, check out the video (embedded below) for a walkthrough. Just remember to do it in a well-ventilated area and wear appropriate PPE.

An alternative to applying Bondo is brush application of UV resin, but we’ve also seen interesting results from non-planar ironing.

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A wrench is shown lying on a machinist’s mat. The end of the wrench holds a ratcheting wheel, on top of which are six independent metal blocks arranged into a hexagon.

Building A Shifting Ratchet Wrench

August 30, 2025 by 13 Comments

Convenient though they may be, [Trevor Faber] found some serious shortcomings in shifting spanners: their worm gears are slow to adjust and prone to jamming, they don’t apply even force to all faces of a bolt head, and without a ratchet, they’re rather slow. To overcome these limitations, he designed his own adjustable ratchet wrench.

The adjustment mechanism is based on a pair of plates with opposing slots; the wrench faces are mounted on pins which fit into these slots, and one plate rotates relative to the other, the faces slide inwards or outwards. A significant advantage of this design is that, since one plate is attached to the wrench’s handle, some of the torque applied to the wrench tightens its grip on the bolt. To let the wrench loosen as well as tighten bolts, [Trevor] simply mirrored the mechanism on the other side of the wrench. Manufacturing proved to be quite a challenge: laser cutting wasn’t precise enough for critical parts, and CNC control interpolation resulted in some rough curves which caused the mechanism to bind, but after numerous iterations, [Trevor] finally got a working tool.

To use the wrench, you twist an outer ring to open the jaws, place them over the bolt, then let them snap shut. One nice touch is that you can close this wrench over a bolt, let go of it, and do something else without the wrench falling off the bolt. Recessed bolts were a bit of an issue, but a chamfer ought to improve this. It probably won’t be replacing your socket set, but it looks like it could make the odd job more enjoyable.

If you prefer a more conventional shifting wrench, you can make a miniature out of an M20 nut. It’s also possible to make a shifting Allen wrench.

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The (RF) Sniff Test

August 29, 2025 by 12 Comments

Sometimes the old tricks are the best. [Kevin] learned an old trick about using a ‘scope to sniff RF noise and pays it forward by sharing it in a recent video. He uses an oscilloscope. But does he need some special probe setup? Nope. He quickly makes a little RF pickup probe, and if you have a ‘scope, we’re pretty sure you can make one in a few seconds, too.

Of course, you can get probes made for that, and there are advantages to using them. But the quick trick of quickly and non-destructively modifying the existing probe to pick up RF means you always have a way to make these measurements.

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Three breakout boards connected with a few wires

Breakout Boards For The Blind

August 29, 2025 by 4 Comments

Connecting an LED to a battery seems trivial. If you have any knowledge of using breadboards, knowing that red goes with red, and that black goes with black, it’s as easy as tying your shoes. Except there’s one problem: what if you can’t see the difference between red and black? [Tara] had a student who struggled with a problem just like this, so of course, they made a whole suite of breakout boards to the rescue!

Breadboards rely almost completely on the visual cues of rows, columns, and if the part is even in the hole correctly. [Tara] fixed these issues while attempting to keep the usefulness of a breadboard. Using tactile cues rather than the traditional visual, a visually impaired individual can figure out what is positive or negative.

Braille is the obvious choice for general communication of inputs and outputs. Where [Tara]’s ingenuity came in was the method of incorporating Braille into the boards — solder joints. After reading a Hackaday article on solder Braille, [Tara] managed a fitting and efficient method of allowing ease of use.

Currently, the boards are in a prototyping stage; however, if you want to try them out yourself early, let [Tara] know. Others with visual impairments are needed to properly stress test the device. If you are someone who does not struggle with any major visual impairments, it can be hard to put yourself in their shoes. For those empathic (and with VR capabilities) among us, be sure to try it yourself!