Machining A Golf Ball To Make A Lovely Tactile Volume Knob

Golf balls are wonderfully tactile things. They have a semi-grippy covering, and they’re a beautiful size and weight that sits nicely in the hand. Sadly, most of them just get smacked away with big metal clubs. [Jeremy Cook] recognized their value as a human interface device, though, and set about turning one into a useful volume knob.

The trick here is in the machining. [Jeremy] used a 3D printed jig to hold a golf ball tightly in place so that it could be machined using a milling machine. With the bottom taken off and a carefully-designed 3D printed insert in the bottom, the golf ball is ready to be used as a knob for a volume control. As for the hardware side of things, [Jeremy] used an existing USB keypad, fitting the golf ball onto the encoder for volume and seek control in various programs.

The results sadly weren’t ideal. While the golf ball sits nicely upon the encoder, [Jeremy] found the device uncomfortable to use. Size may be an issue, but we also suspect the crowding of the surrounding buttons has a role to play. It forces the wrist into an uncomfortable curve to access the ball without hitting the surrounding controls. Without that, it may be greatly improved.

Files are available for those wishing to make their own. We don’t get a lot of golf ball builds here on Hackaday, but we’d love to see more. Hit up the tipsline if you’ve got ’em. Video after the break.

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Binding of the Rab5(GTP) to EEA1 triggers a transition of the EEA1 molecule from a rigid, extended state to a more flexible, collapsed state. (Credit: Anupam Singh et al., 2023)

Not Just ATP: Two-Component Molecular Motor Using GTPase Cycle Demonstrates Mechanotransduction

For most of us who haven’t entirely slept through biology classes, it’s probably no secret that ATP (adenosine triphosphate) is the compound which provides the energy needed for us to move our muscles and for our body to maintain and repair itself, yet less know is guanosine triphosphate (GTP). Up till now GTP was thought to be not used for mechanical action like molecular motors, but recent research by Anupam Singh and colleagues in Nature Physics (press release) has shown that two GTPase hydrolase enzymes (Rab5 and EEA1) function effectively as a reversible molecular motor.

Although much of the heavy lifting in the body has shifted to use ATP with ATPases such as myosin and kinesin, GTPases have retained their functional roles in mostly signal transduction (acting as switches or timers), a tethered EEA1 enzyme performs mechanical force when a Rab5 enzyme (in its activated, GTP state) binds to it. Within e.g. a cell this can pull membranes and other structures together. Most importantly, the researchers found that no external influence was necessary for the inactive (GDP) Rab5 enzyme to separate and EEA1 to revert back to its original state, completing a full cycle.

This discovery not only gives us another intriguing glimpse into the inner workings of biological systems, but also increases our understanding of how these molecular motors work, opening intriguing possibilities for constructing our own synthetic structures such as protein engines, where mechanical movement is needed on scales which require such molecular motors.

(Heading image: Binding of the Rab5(GTP) to EEA1 triggers a transition of the EEA1 molecule from a rigid, extended state to a more flexible, collapsed state. (Credit: Anupam Singh et al., 2023) )

Inside A Current Probe

[The Signal Path] had two Tektronix AC/DC current probes that didn’t work. Of course, that’s a great excuse to tear them open and try to get at least one working. You can see how it went in the video below. The symptoms differed between the two units, and along the way, the theory behind these probes needs some exploration.

The basic idea is simple, but, of course, the devil is in the details. A simple transformer doesn’t work well at high frequencies and won’t work at all at DC. The solution is to use a hall effect sensor to measure DC and also to feed it back to cancel coil saturation.

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Cheaper Sodastream With A Big CO2 Tank Is A Semi-Dangerous Way To Save

Sodastream machines are a fun way to turn tap water into carbonated water. However, the canisters are expensive and generally require a trip to the store to get a replacement. Lifehacker has a workaround that may make life easier for the bubble-addicted set.

The trick is simple: simply buy a larger bottle of CO2, and hook it up to the Sodastream in place of the regular cartridge. CO2 can be bought in large cylinders at a far cheaper rate than Sodastream will charge you for their proprietary canisters. All you need is a local supplier of food-grade CO2 in cylinders, and you can visit them when you need a refill or swap.

There are several caveats, though, which the comment section dicussed when we featured a similar hack before. Getting an extra-large CO2 canister can pose a risk to life if there’s a leak. Alarms may not save you as the heavy gas has a tendency to lurk low to the ground. You should also consider using a regulator to lower the pressure from your large canister to something closer to the levels the Sodastream machine is built to withstand. Beyond that, you want to ensure you’re using food-grade CO2. Don’t go bubbling cheap welding gas through your water if you want to live a long and healthy life.

It’s a neat hack, it’s just one that requires you to practice proper gas safety at all times. Reports are that a cylinder costing less than $200 can last you for several years though, with ultra-cheap refills, so it may indeed be worth the hassle! Go forth and bubble, friends.

Active Racing Simulator Pedal

Racing virtual cars from behind a PC monitor might be cheaper than doing it in the real world, but high-end sim racing peripherals still come with high-end prices. With the increasing popularity of force-feedback pedals [Tristan Fenwick] built built an active pedal that can provide significant resistance.

[Tristan] integrated a load cell into the 3D printed pedal linkage, which is connected to a 130 W NEMA23 servo motor via a 8 mm lead screw. With constant feedback from the load cell, a simple PID controller running on an Arduino to actively adjust the pedal’s position and the amount of resistance it provides.

At ~$250 in parts, it’s a significantly more affordable than the $2300 price tag on a single Simucube pedal, which served as inspiration for this project. There are still some issues to address, such as shaky ADC readings and a lack of computing power on the Arduino, the demo video after the break looks incredibly promising. [Tristan] also notes that 300 kg is overkill and a slightly smaller servo motor would probably also work.

For more incredible simulator inspiration, check out the A-10 Warthog cockpit, a 3D printed flight sim yoke and pedals, and a tank driving simulator from before the age of computer graphics.

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Change Of Plans For New Horizons Sparks Debate

In 2015 NASA’s New Horizons spacecraft provided humanity with the first up-close views of Pluto, passing just 12,472 km (7,750 mi) from the surface. What had always been little more than a fuzzy blip at the edge of the solar system could finally be seen in stunning high resolution. Unfortunately, the deep space probe could only provide us with a relatively fleeting glimpse at the mysterious dwarf planet — the physics of such a distant interplanetary flight meant the energy required to slow down and enter orbit around Pluto was beyond the tiny spacecraft’s abilities.

The craft, often described as being roughly the size and shape of a grand piano, raced past Pluto and its moons at a relative velocity of approximately 49,600 km/h (30,800 mph) and headed out in the direction of Sagittarius. The incredible rate at which New Horizons traveled officially put it on track to be just the fifth spacecraft to leave the solar system, after the Pioneer and Voyager probes. Even so, its onboard systems were still in good health, and if given a sufficiently distant target, the $700 million craft was ready and able to collect more data.

Pluto, as seen by New Horizons

Accordingly, almost exactly a year after it flew over Pluto, New Horizons officially received a mission extension from NASA. As it blasted through deep space, the craft would seek out and study as many objects as it could in the region of space known as the Kuiper belt. Given that there are no current plans to send other spacecraft through this distant area of the outer solar system, New Horizons was uniquely positioned to make what could be once-in-a-lifetime observations.

Or at least, that was the plan. Recently, notes from a May 4th meeting of the Outer Planets Assessment Group (OPAG) were released that revealed NASA’s plans to redirect New Horizons from its work in the Kuiper belt to focus on heliospheric science in 2025. Those in attendance said the meeting became “heated” as New Horizons principal investigator Alan Stern questioned the logic of potentially changing the craft’s mission this late in the game.

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Learn How Impossibly Close-fitting Parts Are Actually Made

Most of us have seen those demonstrations of metal parts that mate together so finely that, once together, they have no visible seam at all. But how, exactly, is this done? [Steve Mould] has a video that shows and explains all, and we’ve never seen the process explained quite like he does.

The secret ingredient is wire EDM, or Electrical Discharge Machining, but that’s only one part of the whole. Wire EDM works a bit like a hot-wire cutter slicing through foam, but all by itself that’s not enough to produce those impossibly close-fitting parts we love to see.

EDM is capable of astounding precision in part because — unlike a cutting tool — nothing physically contacts the material. Also, there isn’t a lot of friction and heat causing small distortions of the material during the machining process. EDM is as a result capable of fantastically-precise cuts, but not invisible ones.

It’s pretty neat to see a water jet used to thread the fine wire through the workpiece.

In all good manufacturing, the capabilities (and limitations) of the tool are taken into account, and this is also true for making those close-fitting pieces. The hole and plug are actually made in two separate stages.

The hole is cut separately from the plug, and because EDM is capable of such finesse, the cuts can be made in such a way that they complement one another with near-perfection. After that, grinding and polishing takes care of the surface finish. The result is the fantastically-smooth and apparently seamless fitment we like so much.

The video is embedded below, and there are some great details about EDM and how it actually works in there. For example, we see how a wire EDM machine can use a jet of water to help thread the wire through a hole in the part to start a job, and we learn that the wire is constantly moving during the process.

As cool as wire EDM is, it is not magic and we’ve seen some pretty remarkable efforts at bringing the technology into the home workshop.
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