Food Safe 3D Printing: A Study

[Matt Thomas] wanted to answer the question of whether 3D printed structures can be food-safe or even medical-safe, since there is an awful lot of opinion out there but not a lot of actual science about the subject. As a mechanical engineer who dabbles in medical technical matters, he designed as series of tests using a wide range of nasty-sounding pathogens, to find once and for all what works and what does not.

One common argument sprung up from the maker movement response to Covid-19; 3D printed masks and visors. Many of us (this scribe included) printed many thousands of visor frames and ear protectors, using the armies of 3D printers we had available, then distributed them to nursing homes and doctors’ surgeries, and anywhere else that couldn’t get ‘proper’ medical-grade items. There was much opinion about the risks associated with contamination of such 3D printed structures, due to the allegedly porous nature of the prints. [Matt] has shown with some SEM imaging, that a typical 3D print does not have any detectable porosity, and that the grooves due to the layer lines are so positively huge compared to your average bacterium, as to also be irrelevant. Continue reading “Food Safe 3D Printing: A Study”

Dirty faders.

Giving Vintage Synths New Life In A Potentiometer Cleaning Showdown

As anyone who has ever owned a piece of older equipment that has a potentiometer in it can attest to, these mechanical components do need their regular cleaning ritual. Whether it’s volume knobs on a receiver or faders on a mixer, over time they get crackly, scratchy and generally imprecise due to the oxidation and gunk that tends to gather inside them.

This is your potentiometer caked with gunk.
This is your potentiometer caked with gunk.

In this blast from the past, [Keith Murray] shows a few ways in which fader-style potentiometers can be cleaned, and how well each cleaning method works by testing the smoothness of the transition over time with an oscilloscope. It’s enlightening to see just how terrible the performance of a grimed-up fader is, and how little a blast of compressed air helped. Contact cleaner works much better, but it’s essential to get all of the loosened bits of gunk out of the fader regardless.

In the end, a soak in isopropyl alcohol (IPA), as well as a full disassembly followed by manual cleaning were the only ones to get the fader performance back to that of a new one. Using contact cleaner followed by blasting the fader out with compressed air seems to be an acceptable trade-off to avoid disassembly, however.

What is your preferred way to clean potentiometers to keep that vintage (audio) gear in peak condition? Let us know in the comments below.

Thanks, [Grant Freese], for the tip!

A robotic turret shooting plastic balls at a man

Automated Turret Keeps Dorm Clean, RoboCop Style

Students’ dorm rooms are not generally known to be the most orderly of places. Whether it’s mountains of dishes in the sink, piles of clothes waiting to be washed, or random bits and bobs strewn across the hallway, cleaning up is pretty low on the agenda for many dorm dwellers.

[Luis Marx] seems to have invented a useful solution to his (or his roommates’) sloppiness: a robotic turret that opens fire on anyone who leaves items unattended (video, in German, embedded below). This system uses a set of “clutter sensors” that can be placed in strategic locations around the house and will detect stray objects using ultrasonic sensors. If any are found, the main system is alerted through WiFi. The turret will then search for any persons in its vicinity and start shooting them with little plastic balls.

The turret in question is a beautifully-designed piece of kit made from 3D printed parts and controlled by an ESP32. It can swivel around its axis and tilt up and down using two servos, while its firing mechanism is driven by a DC motor. It tracks its target thanks to a camera-based object sensor that can recognize humans. The whole thing gives us a bit of a RoboCop vibe; we’d half expect it to shout Pick up those clothes. You have twenty seconds to comply.

While this might not be the definitive solution to messy dorm rooms, we like the creative thinking behind it. We’ve seen auto-targeting turrets before, but not in household applications like this. Of course there are plenty of other robots that can help you with domestic tasks.

Continue reading “Automated Turret Keeps Dorm Clean, RoboCop Style”

An Atari 800 XL, partially covered in battery residue

Massive Cleaning Effort Saves Acid-Drenched Atari

Anyone who’s ever had to deal with the aftermath of a leaking battery knows how much damage such a failure can cause. Degrading batteries leak corrosive chemicals that eat away PCB traces, clog up connectors and generally leave everything looking nasty. Getting your gadget working again usually calls for lots of scrubbing, followed by patiently tracing suspect connections and restoring any broken ones.

We doubt, however, that anyone has ever gone through as much effort as [Lee Smith] has on his Atari 800 XL. This example was listed on eBay in a severely damaged state, having been stored under an entire box of leaking batteries. [Lee] put in a bid and, to his own bemusement, won the auction. He was now the proud owner of a classic gaming machine which was covered in a thick brown crust of battery residue.

A first inspection showed that the damage was more than skin-deep: even inside the computer’s case it was one big mess of crusty brown junk. [Lee] first spent several hours on the plastic case, using different cleaning agents and an ultrasonic bath, and managed to get the case almost spotless again. The keyboard presented a larger challenge however: not only did it require thorough cleaning of every single switch and keycap, the keyboard’s matrix on the PCB had several connections missing, which had to be restored using bodge wires.

With the keyboard working again, [Lee] turned to the mainboard. This turned out to be an even greater challenge, with several components (including a few custom chips) damaged beyond repair. With the help of a few eBay replacements parts and (again) countless hours of scrubbing, the mainboard started to look healthy again. After a few tests, [Lee] felt confident enough to hook up the entire system and turn it on. And his efforts had paid off: the battered Atari dutifully displayed its BASIC prompt, ready for its second lease of life.

We’ve seen before what kind of damage a leaking battery can do to an Amiga, or faulty caps to an Xbox. But both of these seem minor inconveniences compared to what happened to this poor Atari. Thanks to [Simon] for the tip.

Continue reading “Massive Cleaning Effort Saves Acid-Drenched Atari”

DIY Grout Cleaning Machine Does A Good Job

Cleaning tiled floors can be a drag. Getting the tiles themselves clean is bad enough, but often dealing with the grouted joints in between requires more elbow grease and attention to detail. It’s a tedious chore, and thus one ripe for improvement. [Elite Worm]’s cleaning machine is an excellent solution to the problem.

The machine is built entirely from scratch, using primarily 3D printed components. A fluid tank is fitted to the chassis, along with a custom 3D-printed pump run by a DC motor, to deliver cleaning product where its needed. A large DC motor is then used to spin a nylon brush which gets deep in the tile grooves to clean out the grime. The chassis is then fitted with rollers to allow it to glide along the floor. Finally, a handle is fitted which allows the user to push the tool along, with switches to turn on the spinning brush and dispense cleaning fluid.

It’s a great tool, and one which eliminates hours of scrubbing on hands and knees. We’re sure the time investment in the build will pay off before long. We’ve seen other tricky cleaning hacks before, too. Video after the break.

Continue reading “DIY Grout Cleaning Machine Does A Good Job”

Cheap Alternative Solvents For PCB Cleaning

If you’re in the habit of using isopropyl alcohol to clean your PCBs after soldering, you probably have a nice big jug of the stuff stashed away. If you don’t, you’re probably out of luck, since the COVID-19 pandemic has pretty much cleared IPA out of the retail market. But don’t fret: depending on where you live, alternative PCB cleaning solutions may be as close as your nearest auto parts store.

[Steven]’s search for a cheaper and perhaps more readily available substitute for his usual dedicated flux cleaner lead him to try automotive brake cleaner on a few test boards. He suspected that they might contain acetone, which is prone to yield unfortunate results with solder resist and silkscreen on PCBs, so some tests were in order. The brand he tried was Normfest Bremsenreiniger MC-1, a German brand that according to its Safety Data Sheet contains only hydrocarbons like alkanes, butane, and propane. It did a fine job cleaning all but the crustiest rosin flux without collateral damage.

In the video below, [Steven] goes through a few more brands with similar results, and we were encouraged enough by his results to check brake cleaners made for the US market. Alas, almost all of the cheap and readily available aerosols have acetone as the principle ingredient, mixed in with methanol, ethanol, and assorted ingredients that together will probably make for a bad day. About the only US-sold brand without acetone that we could find was Keller-Heartt, which lists only naptha and ethanol on its SDS. There may be others, but make sure you test whatever you find.

Aerosol solvents aren’t the only way to clean a PCB, of course. Ultrasonic cleaners do a great job, and as [Steven] discovered, they’re generally safe for most components.

Continue reading “Cheap Alternative Solvents For PCB Cleaning”

How Safe Is That Ultrasonic Bath For Flux Removal?

How do you clean the residual flux off your boards? There are plenty of ways to go about the job, ranging from “why bother?” to the careful application of isopropyl alcohol to every joint with a cotton swab. It seems like more and more people are turning to ultrasonic cleaners to get the job done, though, and for good reason: just dunk your board and walk away while cavitation does the work for you.

But just how safe is it to sonically blast the flux off your boards? [SDG Electronics] wanted to know, so he ran some cleaning tests to get to the bottom of things. On the face of it, dunking a PCB in an aqueous cleaning solution seems ill-advised; after all, water and electricity famously don’t mix. But assuming all the nooks and crannies of a board can be dried out before power is applied, the cleaning solution itself should be of little concern. The main beef with ultrasonic cleaning seems to be with the acoustic energy coupling with mechanical systems on boards, such as crystal oscillators or micro-electrical-mechanical systems (MEMS) components, such as accelerometers or microphones. Such components could resonate with the ultrasonic waves and be blasted to bits internally.

To test this, [SDG Electronics] built a board with various potentially vulnerable components, including the popular 32.768-kHz crystal, cut for a frequency quite close to the cleaner’s fundamental. The video below goes into some detail on the before-and-after tests, but the short story is that nothing untoward happened to any of the test circuits. Granted, no components with openings as you might find on some MEMS microphones were tested, so be careful. After all, we know that ultrasound can deal damage, and if it can levitate tiny styrofoam balls, it might just do your circuit in.

Continue reading “How Safe Is That Ultrasonic Bath For Flux Removal?”