Tired Of Burnt Fingers? Try PID Tuning The Hot Glue Gun

January 6, 2026 by Tyler August 18 Comments

Hot glue guns are pretty simple beasts: there’s an on/off switch, a heating element, and a source of current, be it battery or wired. You turn it on, and the heater starts warming up; eventually you can start extruding the thermoplastic sticks we call “hot glue”. Since there’s no temperature control, the longer you run the gun, the warmer it gets until it is inevitably hotter than you actually want– either burning you or oozing thermoplastic out the tip. [Mellow_Labs] was sick of that after a marathon hot-glue session, and decided to improve on his hot glue gun with PID tuning in the video embedded below.

PID tuning is probably a familiar concept to most of you, particularly those who have 3D printers, where it’s used in exactly the same way [Mellow_Labs] puts it to work in the hot glue gun. By varying the input (in this case the power to the heater) proportional both to the Parameter (in this case, temperature) as well as the Integral and Derivative of that value, you can have a much steadier control than more naive algorithms, like the simple “on/off” thermostat that leads to large temperature swings.

In this case [Mellow_Labs] is implementing the PID control using a thermistor that looks like it came from a 3D printer, and a MOSFET driven by an RP2040. Microcontroller gets its power via the hot glue gun’s battery fed through a buck converter. Since he has them, a small OLED screen displays temperature, which is set with a pair of push-buttons. Thus, one can set a temperature hot enough to melt the glue, but low enough to avoid oozing or third degree burns.

He does not share the code he’s running on the RP2040, but if you are inspired to replicate this project and don’t want to roll your own, there are plenty of example PID scripts out there, like the one in this lovely robot. No, PID isn’t reserved for thermostats– but if you are controlling heat, it’s not reserved for electric, either. Some intrepid soul put built a PID controller for a charcoal BBQ once. Continue reading “Tired Of Burnt Fingers? Try PID Tuning The Hot Glue Gun” →

Putting The M In A UNI-T MSO

January 5, 2026 by Al Williams 13 Comments

[Kerry Wong] points out that the Uni-T MSO oscilloscopes have a logic analyzer built in — that’s the MSO, or Mixed Signal Oscilloscope, part — but you have to add the probes. He shows you how it works in a recent video below.

He’s looked at the scope’s analog capabilities before and was not unimpressed. The probes aren’t inexpensive, but they do unlock the mixed signal capabilities of the instrument.

Continue reading “Putting The M In A UNI-T MSO” →

Print Your Own Standardized Wire Spool Storage

January 2, 2026 by Donald Papp 22 Comments

Hardware hackers tend to have loads of hookup wire, and that led [firstgizmo] to design a 3D printable wire and cable spool storage system. As a bonus, it’s Gridfinity-compatible!

There are a lot of little design touches we love. For example, we like the little notch into which the wire ends are held, which provides a way to secure the loose ends without any moving parts. Also, while at first glance these holders look like something that goes together with a few screws, they actually require no additional hardware and can be assembled entirely with printed parts. But should one wish to do so, [firstgizmo] has an alternate design that goes together with some M3 bolts instead.

Want to adjust something? The STEP files are included, which we always love to see because it makes modifications to the models so much more accessible. One thing that hasn’t changed over the years is that making engineering-type adjustments to STL files is awful, at best.

If there is one gotcha, it is that one must remove wire from their old spools and re-wind onto the new to use this system. However, [firstgizmo] tries to make that as easy as possible by providing two tools to make re-spooling easier: one for hand-cranking, and one for using a hand drill to do the work for you.

It’s a very thoughtful design, and as mentioned, can also be used with the Gridfinity system, which seems to open organizational floodgates in most people’s minds. Most of us are pinched for storage space, and small improvements in space-saving really, really add up.

Trace Tracing To The Tunes

January 1, 2026 by Al Williams 10 Comments

Some kind of continuity beeper has been a standard piece of gear since the dawn of electronics. Sure, you probably have an ohm meter, but sometimes you don’t care about the actual resistance. You just want to know whether something connects or doesn’t, especially with a PCB trace or a cable. But what if your beeper could tell you more? [Nick Cornford] asks and answers that question with a beeper that lets you estimate resistance via pitch.

The circuit is relatively simple. A short to ground causes a voltage divider to produce a fraction of the battery voltage and a FET to conduct that fractional voltage to a VCO via a high-gain amplifier. The VCO converts voltage to frequency, and an audio amplifier feeds it to the speakers.

The two amplifiers and the VCO require two dual op-amp chips. The original schematic sends the output to some relatively high-impedance headphones. To drive more practical ones, the circuit can drop one op amp and use another FET and a separate battery.

Of course, you have many design choices, especially for the audio amplification. There are plenty of VCO circuits, or you could probably substitute a small microcontroller with an A/D converter and PWM output. Yes, you can also make a VCO with a 555.

VCOs are common because they are at the heart of PLLs.

refurbished baby blue vice next to its refurbisher

Vice Of Old Brought To The Modern Age

December 30, 2025 by Ian Bos 15 Comments

People say they don’t make em’ like they used to, and while this isn’t always the case, it’s certainly true that old vices rarely die with time. This doesn’t mean they can’t use a refresh. [Marius Hornberger] recently backed that up when he decided to restore an old vice that had seen better days.

custom bearing and rod — Customized axial bearing assembly

When refreshing old tools, you’ll almost always start the same: cleaning up all the layers of grease and ruined paint. The stories that each layer could tell will never be known, but new ones will be made with the care put into it by [Marius]. Bearings for the tightening mechanism had become worn down past saving, requiring new replacements. However, simply swapping them with carbon copies would be no fun.

[Marius] decided to completely rethink the clamping mechanism, allowing for much smoother use. To do this was simple, just machine down new axial bearings, design and print a bearing cage, machine the main rod itself, and finally make a casing. It’s simple really, but he wasn’t done and decided to create a custom torque rod to hammer in his vicing abilities. Importantly, the final finish was done by spraying paint and applying new grease.

Old tools can often be given new life, and we are far from strangers to this concept at Hackaday. Make sure to check out some antique rotary tools from companies before Dremel!

Continue reading “Vice Of Old Brought To The Modern Age” →

Printing With Metal On The Ender 3 Using Only A Friction Wheel

December 24, 2025 by Maya Posch 9 Comments

Printing metal as easily as it is to print with thermoplastics has been a dream for a very long time, with options for hobbyists being very scarce. This is something which [Rotoforge] seeks to change, using little more than an old Ender 3 FDM printer and some ingenuity. Best of all is that the approach on which they have been working for the past year does not require high temperature, molten metals and no fussing about with powdered metal.

Additive manufacturing using friction welding. (Credit: Ruishan Xie, et al., j.mtcomm, 2021)

Rather than an extruder that melts a thermoplastic filament, their setup uses metal wire that is fed into a friction welding tool head, the details of which are covered in the video as well as on the GitHub project page. Unlike their previous setup which we reported on last year, this new setup is both safer and much riskier. While there’s no more molten metal, instead a very loud and very fast spinning disk is used to provide the friction required for friction welding, specifically friction and rolling-based additive manufacturing (FRAM) as in the cited 2021 paper by [Ruishan Xie] et al. in Materials Today Communications. By the same lead author there’s also a 2025 paper that explores more complex implementations of FRAM.

Continue reading “Printing With Metal On The Ender 3 Using Only A Friction Wheel” →

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A Compact, Browser-Based ESP32 Oscilloscope

December 21, 2025 by Aaron Beckendorf 36 Comments

An oscilloscope is usually the most sensitive, and arguably most versatile, tool on a hacker’s workbench, often taking billions of samples per second to produce an accurate and informative representation of a signal. This vast processing power, however, often goes well beyond the needs of the signals in question, at which point it makes sense to use a less powerful and expensive device, such as [MatAtBread]’s ESP32 oscilloscope.

Continue reading “A Compact, Browser-Based ESP32 Oscilloscope” →