3D Objects From a Laser Cutter

Actors want to be singers and singers want to be actors. The hacker equivalent to this might be that 3D printers want to be laser cutters or CNC machines and laser cutters want to be 3D printers. When [Kurt] and [Lawrence] discovered their tech shop acquired a 120 Watt Epilog Fusion laser cutter, they started thinking if they could coax it into cutting out 3D shapes. That question led them to several experiments that were ultimately successful.

The idea was to cut away material, rotate the work piece, and cut some more in a similar way to how some laser cutters handle engraving cylindrical objects. Unlike 3D printing which is additive, this process is subtractive like a traditional machining process. The developers used wood as the base material. They wanted to use acrylic, but found that the cut away pieces tended to stick, so they continued using wood. However, the wood tends to char as it is cut.

In the end, they not only had to build special jigs and electronics, they also had to port some third party control software to solve some issues with the Epilog Fusion cutter’s built in software. The final refinement was to use the laser’s raster mode to draw surface detail on the part.

The results were better than you’d expect, and fairly distinctive looking. We’ve covered a similar process that made small chess pieces out of acrylic using two passes. This seems like a natural extension of the same idea. Of course, there are very complicated industrial machines that laser cut in three dimensions (see the video below), but they are not in the same category as the typical desktop cutter.

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A Tale of Three Soldering Iron Controllers

[ZL2PD] needed to replace an old Weller soldering station and decided not to go with one of the cheap soldering stations you can find all over the Internet. He has a long story about why he had to design his own controller, but you never have to explain that to us. He kept detailed notes of his journey and in the end, he built three different controllers before settling on one.

He started with a Hakko hand piece that uses a thermistor for temperature measurements. The first iteration of the controller had analog controls. He wasn’t happy with the number of parts in the design and the simple LED display. That led him to replace the controller with an ATTiny CPU and a use a serial LCD.

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Homebrew Analog Scope Project Log

[GK] had some old CRTs lying around, so naturally he decided to build an old school analog scope with one of them. Lucky for us, he’s been documenting his progress. Since it was a big project to tackle, he started out with Spice modeling to work out all the right values.

Prototyping the power supply took some custom transformer winding, but when done, the power supply did the job. Although he’s still wiring up the Z (intensity) axis, the scope is already capable of displaying signals and even text characters using a character generator he built earlier (see video below).

[GK] spends most of the time so far talking about the high voltage power supply design. For the particular tubes he had on hand he needed +200V, -400V, -550V, and 6.3VAC for the CRT heater. This is certainly not the typical Arduino-based digital scope that everyone builds at least once.

We love analog scopes for art projects, logic analyzer conversions, and gaming. Of course, if you don’t have an old CRT in your parts bin, you might consider trying a laser.

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RC Lawnmower Has No Grass to Cut

They say laziness and necessity is one of the greatest drives for invention. Whoever said that didn’t think about what happens when inventors are bored. [The Random Mechanic] decided to build himself a remote-controlled lawnmower, despite the terrible drought he’s been having — resulting in literally no grass to cut.

To make the lawn mower remote-controlled, he cobbled together a gas lawn mower, with the remains of an electric wheelchair. This ended up working really well. He’s using an old RC car remote and its two servos to remotely control the original wheel chair’s joystick. Simple, but super effective.

The wheelchair mower is fast, nice and heavy thanks to some lead acid batteries, and very maneuverable with the front wheels being casters. It’s a shame he doesn’t have any grass to cut!

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Custom Threaded Inserts for 3D Printing

There’s a variety of ways to add threaded holes to 3D printed objects. You can tap a hole, but the plastic isn’t always strong enough. Nut traps work, but aren’t very attractive and can be difficult to get exactly the right size. If you try to enclose them, you have to add a manual step to your printing process, too. You can buy threaded inserts (see video below) but that means some other piece of hardware to have to stock in your shop.

[PeterM13] had a different idea: Cut a piece of threaded stock, put nuts on the end and heat it up to let the nuts reform the plastic. This way the nut traps wind up the perfect size by definition. He used two nuts aligned and secured with thread locker. Then he used a hot air gun to only heat the metal (so as to reduce the chance of deforming the actual part). Once it was hot (about 15 seconds) he pulled the nuts into the open hole, where it melted the plastic which grips the nuts once cooled again.

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Cheap Function Generator Teardown and Improvement

In general, you get what you pay for, and when [Craig] picked up a cheap function generator off eBay, he didn’t expect much from it. But as he shows us in his blog post and a series of videos below, while the instrument lived down to his expectations, he was able to fix it up a bit.

Having spent only $100USD for the MHS-5200A, [Craig]’s adventure is a complete teardown and analysis of the function generator. While it sort of lives up to its specs, it’s pretty clear that some design decisions resulted in suboptimal performance. At higher frequencies and higher amplitudes, the sine wave output took on a markedly non-sinusoidal character, approaching more of a triangle waveform. The spectrum analyzer told the tale of multiple harmonics across the spectrum. With a reverse-engineered schematic in hand, he traced the signal generation and conditioning circuits and finally nailed the culprit – an AD812 op-amp used as the final amplifier. An in-depth discussion of slew rate follows in part 2, and part 3 covers replacement of the dodgy chip with a better selection that improves the output signal. We’re also treated to improvements to a low-pass filter that fixed a nasty overshoot and ringing problem with the unit’s square wave function.

If hacking the MHS-5200A seems a bit familiar to you, that’s because we covered another reverse-engineering exploit of it recently. That hack of the serial protocol of the instrument was by [WD5GNR], also known as Hackaday’s own [Al Williams]. Cheers to both [Craig] and [Al] for showing us what you can do with a hundred bucks and a little know-how.

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Modified Mower Hacks the Heavy Stuff

Clearing brush is no fun. Sure, swinging a machete on a hot, humid day sounds great, but when you’re sitting in an oatmeal bath the next day because you didn’t see the poison ivy, you’ll be looking for a better way. [RoboMonkey] did just that with a field-expedient brush trimmer that’s sure to help with his chores.

This is a hack in the true Junkyard Wars sense of the word. A cast-off electric push mower deck caught [RoboMonkey]’s eye, and a few spare brackets and bolts later his electric hedge trimmer was attached across the front of the mower. With a long extension cord trailing behind, he was able to complete in 10 minutes what would normally take him an hour to accomplish, without spending a dime on either a specialized brush cutter or a landscaping service. The video after the break reveals that it may not be the most powerful tool in the shed, and it won’t likely stand up to daily use, but for this twice a year chore, it’s more than sufficient. And since the hedge trimmer wasn’t modified, it’s still available for its original purpose. Reduce, reuse, recycle – and repurpose.

While we haven’t seen many brush cutters before, we seen plenty of mower mods. From LiPo electrics to a gas-powered RC unit, the common push-mower seems to be a great platform for all kinds of hacking.

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