The Best Robot Mop System: Flat, Spinning, Or Roller?

When it comes to designing a mopping robot, there are a number of approaches you can pick from, including just having the movement of the robot push the soggy mop over the floor, having spinning pads, or even a big spinning roller. But what difference does it make? Recently the [Vacuum Wars] channel ran a comparison to find out the answer.

The two spinning pad design is interesting, because it allows for the bot to move closer to objects or walls, and the base station doesn’t need the active scrubber that the simple static pad requires. The weakness of both types of flat mop design is that they are quickly saturated with dirt and moisture, after which they’ll happily smear it over the floor.

The spinning roller is the most complex, with the robot having its own onboard water tank, and a way to extract the dirty water from the mop and store it for disposal in the base station. Theoretically this would be the clear winner, with basically all of them having features like avoiding carpet.

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Get Bored!

My son went over to a friends house this afternoon, when my wife had been planning on helping him with his French homework. This meant she had an hour or so of unexpected free time. Momentarily at a loss, she asked me what she should do, and my reply was “slack off”, meaning do something fun and creative instead of doing housework or whatever. Take a break! She jokingly replied that slacking off wasn’t on her to-do list, so she wouldn’t even know how to start.

But as with every joke, there’s more than a kernel of truth to it. We often get so busy with stuff that we’ve got to do, that we don’t leave enough time to slack, to get bored, or to simply do nothing. And that’s a pity, because do-nothing time is often among the most creative times. It’s when your mind wanders aimlessly that you find inspiration for that upgrade to the z-stage on your laser cutter, or whatever the current back-burner project of the moment is.

You don’t get bored when you’re watching TV, playing video games, or scrolling around the interwebs on your phone, and it’s all too easy to fall into these traps. To get well and truly bored requires discipline these days, so maybe putting “slack” into your to-do list isn’t a bad idea after all. My wife was right! And that’s why I volunteered to take my son to parkour on Sundays – it’s and hour of guaranteed, 100% uninterruptible boredom. How do you make sure you get your weekly dose of slack?

Arnis Brings The World To Minecraft: Bedrock Edition

A couple of years ago, we covered a project called Arnis, created by [Louis Erbkamm], which allowed you to generate any portion of Earth into Minecraft blocks and maps. It was already impressive, but since we last checked in the open source project has made some incredible progress.

When we first covered Arnis, it was stuck on the Java edition of Minecraft. But now the project has been updated to support the more modern Bedrock Edition, meaning you can put your home into any device’s version of Minecraft!

Beyond Bedrock version support, the actual tool has improved with proper elevation generation using data provided from NASA. This allows you to view the Alps or the Himalayas in all their voxel glory, or explore an entire map of the Moon. Perhaps what’s even more impressive is that the generation is accurate enough to be used in an actual research study involving flood mitigation education.

All of this has been made possible with help from a passionate community who have volunteered their time to assist [Louis] with the project — a testament to the power of open source.

The EMac: Using Apple’s Forgotten Educational Mac In 2026

Beauty truly is in the eye of the beholder. (Credit: MattKC, YouTube)
Beauty truly is in the eye of the beholder. (Credit: MattKC, YouTube)

What’s it like to use a 2002-era Apple eMac all-in-one in 2025? That’s what [MattKC] asked himself after obtaining one of these systems from a seller who ominously mentioned that it had been ‘left outside for years’.

The Apple iMac is a bit of a cult symbol, whether you’re talking about the iconic fruity iMac G3 or the desk lamp-like iMac G4, but few reminisce or actively collect the Apple eMac. Manufactured from 2002 to 2006, it featured the PowerPC 7450 (G4e) CPU with clock speeds ranging from 700 MHz to 1.42 GHz, as well as a 17″ CRT. In terms of design it was basically a bland iMac G3 that was firmly targeting the education markets to try and regain market share after Windows PCs had begun to eat its lunch there.

As for the model that [MattKC] purchased, it was this earliest model, featuring a 700 MHz PowerPC G4 CPU in addition to 640 MB SDRAM. Despite the seller’s description it seems to be in good nick with it firing right up, and even a glance inside after beating the challenge of 2.5 mm hex screws showed it to be in relatively good condition.

Unlike the iMac G3, you can play the Mac port of Halo on it, but the Minecraft port is very much not performant. With generally multimedia and gaming working well, it does show why the eMac was released, as it’s quite capable relative to an iMac G3 which would have struggled with the educational software of the era. We definitely hope that [MattKC] restores it to its full glory instead of ripping out its innards, as the neglected status of the eMac makes it much more likely to go extinct than PowerPC-based iMacs.

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DIY, Full-Stack Farm Automation

Recently, [Vinnie] aka [vinthewrench] moved from Oregon to Arkansas to start a farmstead. This is a style of farming that focuses not just on a profitable farm where produce is sold at market, but also on a homestead where much of one’s own food is grown on the farm as well. Like any farm, though, it’s extremely hard work that takes a tremendous amount of time. Automation and other technology can make a huge impact in these situations, and [Vinnie] is rolling out his own software stack to help with this on his farm.

He calls his project the Pi Internet of Things, or PioT, and as its name suggests is based around the Raspberry Pi. Since this will all be outdoors and exposed to the extremes of Arkansas weather, everything built under the auspices of this project prioritizes ruggedness, stability, and long-term support, all while avoiding any cloud service. The system also focuses on being able to ride through power outages. The server side, called piotserver, uses a REST API to give the user access to the automation systems through a web interface

[Vinnie] also goes into detail about why existing systems like Home Assistant and Open Sprinkler wouldn’t work in his situation, and why a ground-up solution like this is more appropriate for his farm. This post is largely an overview of his system, but some of his other posts go into more detail about things like integrating temperature sensors, rainfall monitoring, controlling irrigation systems, and plenty of other farm automation tasks that are useful for any farmer or gardener.

We’ve also seen some other projects of his here like this project which converts a common AC sprinkler system to an easier-to-use DC system, and a DIY weather station that operates in the 915 MHz band. He’s been a great resource for anyone looking to have technology help them out with their farm or garden, but if you’re just getting started on your green thumb be sure to take a look at this starter guide as well.

How Accurate Is A 125 Year Old Resistance Standard?

Internals of the 1900 Evershed & Vignoles Ltd 1 ohm resistance standard. (Credit: Three-phase, YouTube)
Internals of the 1900 Evershed & Vignoles Ltd 1 ohm resistance standard. (Credit: Three-phase, YouTube)

Resistance standards are incredibly useful, but like so many precision references they require regular calibration, maintenance and certification to ensure that they stay within their datasheet tolerances. This raises the question of how well a resistance standard from the year 1900 performs after 125 years, without the benefits of modern modern engineering and standards. Cue the [Three-phase] YouTube channel testing a genuine Evershed & Vignoles Ltd one ohm resistance standard from 1900.

With mahogany construction and brass contacts it sure looks stylish, though the unit was missing the shorting pin that goes in between the two sides. This was a common feature of e.g. resistance decade boxes of the era, where you inserted pins to connect resistors until you hit the desired total. Inside the one ohm standard is a platinoid resistor, which is an alloy of copper, nickel, tungsten, and zinc. Based on the broad arrow mark on the bottom this unit was apparently owned by the UK’s Ordnance Board, which was part of what was then called the War Office.

After a quick gander at the internals, the standard was hooked up to a Keithley DMM7510 digital bench meter. The resistance standard’s ‘datasheet’ is listed on top of the unit on the brass plaques, including the effect of temperature on its accuracy. Adjusting for this, the measured ~1.016 Ω was within 1.6% tolerance, with as sidenote that this was with the unit not having been cleaned or otherwise having had maintenance performed on it since it was last used in service. Definitely not a bad feat.

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Testing A Continuous Printing Mod For The Bambu Lab A1 Mini

There are a few types of continuous 3D printing with FDM printers, with a conveyer belt and automatic build plate swapping the most common types. The advantage of build plate swapping is that it automates the bit where normally a human would have to come in to remove finished parts from the build plate. A recent entry here is the Chitu PlateCycler C1M which the [Aurora Tech] YouTube channel had over for a review. This kit bolts onto the Bambu Lab A1 Mini FDM printer and comes with four extra PEI build plates for a not unreasonable $79 (€69).

As also noted in the review video, this is effectively a clone of the original swapmod A1m kit, but a big difference is that the Chitu kit comes with all of the parts and doesn’t require you to print anything yourself.

The different plates are prepared using a special tool that inserts G-code between the plate changes. Moving the bed in a specific way triggers the switch that lifts the finished plate off the magnetic bed by the plastic grip on the plate and loads a fresh plate from the stack. Here it was found that a small tolerance issue prevented the last plate from being used, but some sandpaper fixed this. Other than that it was a fairly painless experience, and for e.g. multi-color prints with separated colors – as demonstrated – it would seem to be a great way to churn out the entire model without manual intervention or a lot of wasted filament.

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