Testing 3D Printed Cutting Blades Is Scary Work

[Ivan Miranda] comes from a land where the shops close on Sundays. Thus, when he found himself in need of a cutting blade, he realised he would have to build his own, or simply wait. He elected to do the former, and we get to enjoy the journey. (Video, embedded below.)

His first attempt was to cut a wooden plank with a 3D-printed cutting blade fitted to a mitre saw. After setting up the mitre saw to cut while he was at a safe distance, [Ivan] elected to test the blade. Alas, it simply melted, and the wood was barely scratched, so [Ivan] went back to the drawing board.

His second attempt was to CNC mill an aluminium blade, which was a full 6 mm thick. The saw needed some modifications to the saw to fit properly, but it was able to cut wood without major drama!

Returning to the 3D-printed concept, [Ivan] suspected reducing the surface speed of the cutting disc could reduce friction-induced heating. This would allow the 3D-printed blade to cut wood without melting, in theory. To achieve this, he built his own basic drop saw using a steel frame and a brushless motor. With a little water spray, and careful control of speed and pressure, the blade was able to slowly chew through a plank of wood. Afterwards, the teeth were almost completely worn down.

The fact is, 3D-printed blades are usually going to be too soft to do any real useful work. However, it’s fun to watch, and that’s good enough for us. If you want something more useful though, consider building your own knives.

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Can We Repurpose Old Wind Turbine Blades?

Wind turbines are a fantastic, cheap, renewable source of energy. However, nothing lasts forever, and over time, the blades of wind turbines fatigue and must be replaced. This then raises the question of what to do with these giant waste blades. Thankfully, a variety of projects are exploring just those possibilities.

A Difficult Recycling Problem

Around 85% of a modern wind turbine is recyclable. The problem is that wind turbine blades currently aren’t. The blades last around 20 to 25 years, and are typically made of fiberglass or carbon fiber. Consisting of high-strength fibers set in a resin matrix, these composite materials are incredibly difficult to recycle, as we’ve discussed previously. Unlike metals or plastics, they can’t just be melted down to be recast as fresh material. Couple this with the fact that wind turbine blades are huge, often spanning up to 300 feet long, and the problem gets harder. They’re difficult and expensive to transport and tough to chop up as well.

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Full Size 3D-Printed Wind Turbine

Wind energy isn’t quite as common of an alternative energy source as solar, at least for small installations. It’s usually much easier just to throw a few panels and a battery together than it is to have a working turbine with many moving parts that need to be maintained when only a small amount of power is needed. However, if you find yourself where the wind blows but the sun don’t shine, there are a few new tools available to help create the most efficient wind turbine possible, provided you have a 3D printer.

[Jan] created this turbine with the help of QBlade, a piece of software that helps design turbine blades. It doesn’t have any support for 3D printing though, such as separating the blades into segments, infill, and attachment points, so [Jan] built YBlade to help take care of all of this and made the software available on the project’s GitHub page. The blades are only part of this story, though. [Jan] goes on to build a complete full-scale wind turbine that can generate nearly a kilowatt of power at peak production, although it does not currently have a generator attached and all of the energy gets converted to heat.

While we hope that future versions include a generator and perhaps even pitched blades to control rotor speed, [Jan] plans to focus his efforts into improving the blade design via the 3D printer. He is using an SLA printer for these builds, but presumably any type of printer would be up to the task of building a turbine like this. If you need inspiration for building a generator, take a look at this build which attempted to adapt a ceiling fan motor into a wind turbine generator.

 

Watch This LEGO Pantograph Carve Chocolate Messages

[Matthias Wandel] is best known for his deeply interesting woodworking projects, so you might be forgiven for not expecting this lovely chocolate-engraving pantograph made from LEGO. With it, he carves a delightful valentine’s message into a square of chocolate, but doesn’t stop there. He goes the extra mile to cut the chocolate carefully into a heart, and a quick hit with a heat gun takes the rough edges off for a crisp and polished end result.

The cutting end is a small blade stuck inside a LEGO piece, but that’s the only non-LEGO part in the whole assembly. A key to getting a good carve was to cool the chocolate before engraving, and you can see the whole process in the video embedded below.

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Rechargeable Robot Mows Lawns

Perhaps one day our robot overlords will look back on all of the trivial things that humans made them do and take retribution on us. Until then, though, there’s no problem having them perform all of our chores. [v.loschiavo] is also exploiting our future rulers and built a robot that mows his lawn automatically as his entry into the 2018 Hackaday Prize.

The robot uses a rechargeable battery system to drive a nylon blade for grass cutting. It also has an obstacle detection and avoidance system that allows it to find the borders of your yard and keep from getting stuck against shrubs and flower beds. And don’t worry about safety, either. There’s a built-in system of sensors that prevents any injuries from occurring. The robot also has a 10 Watt solar panel on the top that helps recharge the battery, but it can also recharge at a base station similar to a Roomba.

The whole robot was 3D printed with the exception of some parts like the cutting motor, solar panel, and gear motors. While nothing except for the pictures and a general overview of the robot has been posted to the project page yet, we hope [v.loschiavo] updates the project with the G-code files, code, and schematics so we can build our own.

What To Do With Your Brand New Ultrasonic Transducer

We wager you haven’t you heard the latest from ultrasonics. Sorry. [Lindsay Wilson] is a Hackaday reader who wants to share his knowledge of transducer tuning to make tools. The bare unit he uses to demonstrate might attach to the bottom of an ultrasonic cleaner tank, which have a different construction than the ones used for distance sensing. The first demonstration shows the technique for finding a transducer’s resonant frequency and this technique is used throughout the video. On the YouTube page, his demonstrations are indexed by title and time for convenience.

For us, the most exciting part is when a tuned transducer is squeezed by hand. As the pressure increases, the current drops and goes out of phase in proportion to the grip. We see a transducer used as a pressure sensor. He later shows how temperature can affect the current level and phase.

Sizing horns is a science, but it has some basic rules which are well covered. The basic premise is to make it half of a wavelength long and be mindful of any tools which will go in the end. Nodes and antinodes are explained and their effects demonstrated with feedback on the oscilloscope.

We have a recent feature for an ultrasonic knife which didn’t cut the mustard, but your homemade ultrasonic tools should be submitted to our tip line.

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Fail Of The Week: The Little Ultrasonic Knife That Couldn’t

We all know the feeling of an idea that sounded great when it was rattling around in our head, only to disappoint when we actually build the thing. It’s a natural consequence of trying new stuff, and when it happens, we salvage what we can and move on, hopefully in wisdom.

The thing that at least semi-defeated [This Old Tony] was an attempt to build an ultrasonic cutter, and it didn’t go well. Not that any blood was shed in the video below, although there seemed like there would be the way [Old Tony] was handling those X-Acto blades. His basic approach was to harvest the transducer and driver from a cheap ultrasonic cleaner and retask the lot into a tool to vibrate a knife rapidly enough to power it through tough materials with ease.

Spoiler alert: it didn’t work very well. We think the primary issue was using a transducer that was vastly underpowered compared to commercial (and expensive) ultrasonic cutters, but we suspect the horn he machined was probably not optimized either. To be fair, modeling the acoustic performance of something like that isn’t easy, so we can’t expect much. But still, it seems like the cutter could have worked better. Share your thoughts on how to make version 2.0 better in the comments.

The video is longish, but it’s as entertaining as any of [Old Tony]’s videos, and packed full of incidental gems, like the details of cavitation. We enjoyed it, even if the results were suboptimal. If you want to see a [This Old Tony] project that really delivers, check out his beautiful boring head build.

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