[Christian]’s central ventilation and water heating is handled by a heat pump, which uses a lot of electricity, especially in the Austrian winter. When it draws in cool air, it first needs to heat it to the thermostat temperature before venting it to the house. Cryptocurrency mining rigs are also heavy electricity users, but they also produce a lot of heat, which can be used to preheat the air going to the heat pump. [Christian] had four older AMD R9 390 GPUs (equivalent to the Nvidia GeForce GTX 970) lying around, so he mounted them in a server case and piped the heat pump’s air intake through the case.
At the time he did the tests, earnings from mining were enough to cover half of his heating bill, even after paying for the mining rig’s electricity. That is not taking into account the electricity savings from the preheated air. He only shows the results of one evening, where it dropped his electricity usage from around 500Wh to below 250Wh. We would like to see the long-term results, and it would be an interesting challenge to build a model to calculate the true costs or savings, taking into account all the factors. For instance, it could be possible to save costs even if the mining rig itself is running at a slight loss.
Of course, this is not a new idea. A quick internet search yields several similar projects and even some commercial crypto mining space heaters. We do like the fact that [Christian] reused some hardware he already had and integrated it into his central heating rather than using it as a mobile unit.
3D printers, desktop CNC mills/routers, and laser cutters have made a massive difference in the level of projects the average hacker can tackle. Of course, these machines would never have seen this level of adoption if you had to manually write G-code, so CAM software had a big part to play. Recently we found out about an open-source browser-based CAM pack created by [Stewert Allen] named Kiri:Moto, which can generate G-code for all your desktop CNC platforms.
To get it out of the way, Kiri:Moto does not run in the cloud. Everything happens client-side, in your browser. There are performance trade-offs with this approach, but it does have the inherent advantages of being cross-platform and not requiring any installation. You can click the link above and start generating tool paths within seconds, which is great for trying it out. In the machine setup section you can choose CNC mill, laser cutter, FDM printer, or SLA printer. The features for CNC should be perfect for 90% of your desktop CNC needs. The interface is intuitive, even if you don’t have any previous CAM experience. See the video after the break for a complete breakdown of the features, complete with timestamp for the different sections.
All the required features for laser cutting are present, and it supports a drag knife. If you want to build an assembly from layers of laser-cut parts, Kiri:Moto can automatically slice the 3D model and nest the 2D parts on the platform. The slicer for 3D printing is functional, but probably won’t be replacing our regular slicer soon. It places heavy emphasis on manually adding supports, and belt printers like the Ender CR30 are already supported.
[Amy Makes Stuff] has long used a pair of diamond honing blocks to freehand sharpen planes, chisels, and all the other dull things around the shop. Although this method works fairly well, the results are often inconsistent without some kind of jig to hold the blade securely as it’s being sharpened. These types of devices are abundant and cheap to buy, but as [Amy] says in the video after the break, then she doesn’t get to machine anything. Boy, do we know that feeling.
[Amy] was able to make this completely out of stuff she had lying around, starting with a block of scrap aluminium that eventually gets cut into the two halves of the jig. The video is full of tips and tricks and it’s really interesting to see [Amy]’s processes up close. Our favorite part has to be that grippy knob that expands and contracts the jig. [Amy] made it by drilling a bunch of holes close to the outside edge of a circle, and then milled away the edge until she had a fully fluted knob. Once she had the jig finished, she upgraded her honing blocks by milling a new home for them out of milky-white high-density polyethylene.
The availability of small and powerful brushless motors has been instrumental in the development of so-called micro-mobility vehicles. But if your commute involves crossing a frozen lake, you might find the options a bit lacking. Fortunately [Simon] from [RCLifeOn] now has a solution for you in the form of motorized ice skates.
[Simon] used 3D printed brackets to mount outrunner brushless motors to the back of a pair of ice-skates. The spinning outer housing of the motor is used as the wheel, with a bunch of studs threaded in it to dig into the ice and provide traction. At first [Simon] tried to use a pair of RC car springs to keep the motor in contact with the ice, but spring force was insufficient for the task, so he ended up rigidly mounting the motors. Getting proper traction on the ice from a standstill was still tricky, so he ended up leaning back to push the motor down, which also had the effect of putting him off balance, limiting the practical acceleration. The most obvious solution for the tracking problem seems to be stronger springs, but we assume he didn’t have any on hand. The batteries are held in a backpack, with cables running down to the skates, and a wireless electric skateboard controller is used for throttle control.
The obvious risk of these skates is of the studded motors inadvertently becoming meat grinders if you fall. It still looks like a fun project, and we wouldn’t mind having a go on those skates.
Getting into e-biking is a great hobby. It can get people on bikes who might otherwise not be physically able to ride, it can speed up commute times, and it can even make hauling lots of stuff possible and easy, not to mention it’s also fun and rewarding. That being said, there are a wide array of conflicting laws around what your e-bike can and can’t do on the road and if you don’t want to run afoul of the rules you may need a programmable device that ensures your e-bike is restricted in the appropriate way.
This build is specifically for Bafang mid drives, which can be up to 1000 W and easily power a bike beyond the speed limit where [Tomblarom] lives. A small microcontroller is housed in a waterproof box on the bike and wired between the motor’s display and controller. A small hall effect sensor and magnet sit by this microcontroller, and if the magnet is removed then the microcontroller reprograms the bike’s controller to limit the speed and also to disable the throttle, another feature that is illegal in some jurisdictions but not others. As an added bonus, the microcontroller also handles brake lights, turn signals, and automatic headlights for the bike as well.
While the project page mentions removing the magnet while getting pulled over to avoid fines and other punishments, that’s on you. We imagine this could still be useful for someone who wants to comply with local laws when riding on the road, but still wants to remove the restrictions when riding on private property or off-road where the wattage and speed restrictions might not apply.
We have to admit that flying cars still sound pretty cool. But if we’re ever going to get this idea off the ground, there’s a truckload of harsh realities that must be faced head-on. The most obvious and pressing issue might seem to be the lack of flying cars, but that’s not really a problem. Air taxis are already in the works from companies like Airbus, Rolls-Royce, and Cadillac, who premiered theirs at CES this year.
Laser cutting equipment runs the gamut in terms of cost, with low-end, almost disposable units that can be had for a song to high-power fiber lasers that only big businesses can afford. But the market has changed dramatically over the years, and there’s now a sweet-spot of affordable laser cutters that can really do some work. And while plenty of hobbyists have taken the plunge and added such a laser cutter to their shops, still others have looked at these versatile tools and realized that a business can be built around them.
For the next Hack Chat, we’ll be sitting down with Jonathan Schwartz. He started with laser cutters at his maker space, and quickly became the “laser guy” everyone turned to for answers. With about 10 years of experience, Jon set up American Laser Cutter in Los Angeles, to provide bespoke laser engraving and cutting services. He has built a business around mid-range laser cutters, and he’s ready to share what he’s learned. Join us as we talk about the machines, the materials, and the services that are part of a laser cutting business, and find out some of the tricks of the laser-jockey’s trade.
Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.