Fire Extinguishers, Optical Density Ratings And Safely Using Home Lasers

Ski goggle type laser safety lenses may look dorky, but they leave no gaps and fit around glasses. (Credit: FauxHammer, YouTube)
Ski goggle type laser safety lenses may look dorky, but they leave no gaps and fit around glasses. (Credit: FauxHammer, YouTube)

After [Ross] from FauxHammer miniature model fame got lured into reviewing laser engravers and similar via the Bambu Lab H2D’s laser module, he found himself getting slightly nervous about the whole ‘safety’ aspect of these lasers. After all, lasers can not only light stuff on fire, but it’s a well-known fact that even reflected laser light can be sufficient to cause permanent damage to your retinas. Or worse.

Since your eyes generally do not regenerate, it makes sense to get caught up on laser safety before turning on one of those plentiful-and-increasingly-affordable home laser systems for engraving and/or cutting.

While the issue of stuff catching on fire is readily solved by having a good CO2 extinguisher – and plan B options – at the ready, for safety glasses it’s significantly more complex. There’s not just the issue of finding glasses that block the wavelength of the laser system that you are using, but also with the right optical density (OD) rating. Every mm of the safety lens material can attenuate a certain amount of laser light at the given wavelength, so the OD rating of your laser safety goggles need to match the laser’s power output level, or you might be living with a false sense of security.

Finally, there is the issue of the smoke and fumes produced by these lasers as they obliterate the target material. Much of what is in this smoke you do not want to breathe in, even ignoring long-term dust and VOC exposure issues, so having a solid fume extraction setup and PPE as necessary are absolute necessities. As [Ross] puts it, you don’t want to breathe in the smell of regret today, for your future self to reflect on a decade from now.

Work safe, work smart, don’t become the subject of a laser safety PSA.

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Engrave A Cylinder Without A Rotary Attachment? No Problem!

Laser-engraving a cylindrical object usually requires a rotary attachment, which is a motorized holder that rotates a cylindrical object in sync with the engraver. But [Samcraft] shows that engraving all around a mug can be done without a motorized rotary holder.

Separating a design into elements thin enough to engrave individually without losing focus is the key.

The basic idea is to split the design into a number of separate engraving jobs, each containing one element of the overall design, then setting the mug into a 3D printed jig and manually rotating it between jobs. To demonstrate, [Samcraft] selects a series of line-art flowers and plants which are ideal for this approach because there’s no need to minutely register the individual engravings with one another.

What about focus? [Samcraft] found that a design up to 45 mm wide could be engraved onto the curved surface of his mug before focus suffers too much. It’s true that this technique only works with certain types of designs — specifically those with individual elements that can be separated into tall and thin segments — but the results are pretty nice.

Laser engravers are a very serious potential eye hazard, and we are not delighted to see the way the shield around [Samcraft]’s engraver cannot close completely to accommodate the mug while the laser is active. But we’re going to assume [Samcraft] has appropriate precautions and eye protection in place off-camera, because laser radiation and eyeballs absolutely do not belong together, even indirectly.

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Exposed inner copper on multilayer PCB. (Credit: mikeselectricstuff, YouTube)

LACED: Peeling Back PCB Layers With Chemical Etching And A Laser

Once a printed circuit board (PCB) has been assembled it’s rather hard to look inside of it, which can be problematic when you have e.g. a multilayer PCB of an (old) system that you really would like to dissect to take a look at the copper layers and other details that may be hidden inside, such as Easter eggs on inner layers. [Lorentio Brodeso]’s ‘LACED’ project offers one such method, using both chemical etching and a 5 Watt diode engraving laser to remove the soldermask, copper and FR4 fiberglass layers.

This project uses sodium hydroxide (NaOH) to dissolve the solder mask, followed by hydrogen chloride (HCl) and hydrogen peroxide (H2O2) to dissolve the copper in each layer. The engraving laser is used for the removing of the FR4 material. Despite the ‘LACED’ acronym standing for Laser-Controlled Etching and Delayering, the chemical method(s) and laser steps are performed independently from each other.

This makes it in a way a variation on the more traditional CNC-based method, as demonstrated by [mikeselectricstuff] (as shown in the top image) back in 2016, alongside the detailed setup video of how a multi-layer PCB was peeled back with enough resolution to make out each successive copper and fiberglass layer.

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Memorialize Your Favorite Chips In Slate

There’s no point in denying it — if you’re a regular reader of Hackaday, you’ve almost certainly got a favorite chip. Some in the audience yearn for the simpler days of the 6502, while others spend their days hacking on modern microcontrollers like the ESP32 or RP2040. There are even some of you out there still reaching for the classic 555. Whatever your silicon poison, there’s a good chance the Macrochips project from [Jason Coon] has supersized it for you.

The original slate RP2040

The idea is simple: get a standard 100 mm x 100 mm (4″ x 4″) slate coaster, throw it in your laser engraver of choice, and zap it with a replica of a chip’s label. The laser turns the slate a light gray, which, when contrasted with the natural color of the slate, makes for a fairly close approximation of what the real thing looks like. To date, [Jason] has given more than 140 classic and modern chips the slate treatment. Though he’s only provided the SVGs for a handful of them, we’re pretty sure anyone with a laser at home will have the requisite skills to pull this off without any outside assistance.

The page credits a post from [arturo182] for the idea (Nitter), which pointed out a slate RP2040 hiding out on the corner of [Graham Sanderson]’s desk back in 2021. We just became aware of the trend when [Jason] posted his freshly engraved RP1 on Mastodon in honor of the release of the Raspberry Pi 5.

Laser Engraving, Up Close

You know you aren’t supposed to watch your laser while it is cutting or engraving. But [Alex] hosted Wired in his studio and showed them how lasers engrave metal with a fiber laser. You can see the video below.

If you haven’t used a fiber laser, you might be surprised that while a 60 W model can burn metal, it does absolutely nothing to [Alex’s] hand. We wouldn’t try that, by the way, with the common diode lasers you see in most hacker’s labs these days. The video isn’t terribly technical, but it is interesting to see different metals succumb to the powerful laser. There are a few tips about marking different metals in different ways and how to deal with thermal expansion and other effects.

Fiber lasers aren’t as common as diode engravers in private shops, but we assume it is just a matter of time before they get cheaper. Not to mention their widespread use commercially means surplus units might become available, too.

If you are interested in lasers, [Alex’s] YouTube channel has quite a few interesting videos to check out. If you need more power, how’s 200 kW? Then again, even 20 W will get you something useful.

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Open Source Replacement For EzCAD

[Bryce] obtained a fiber laser engraver to use for rapid PCB prototyping last Fall. But he was soon frustrated by the limitations of the standard EzCAD software that typically comes with these and similar devices — it is proprietary, doesn’t have features aimed at PCB manufacturing, only runs on Windows, and is buggy. As one does, [Bryce] decided to ditch EzCAD and write his own tool, Balor, named after the King of the Fomorians.

The controller board in [Bryce]’s machine is a Beijing JCZ LMCV4-FIBER-M board, containing an Altera FPGA and a Cypress 8051 USB controller. So far, he hasn’t needed to dump or modify the FPGA or 8051 code. Instead, he sorted out the commands by just observing the USB operations as generated by a copy of EzCAD running know operations. A lot of these engraving systems use this control board, but [Bryce] want’s to collect data dumps from users with different boards in order to expand the library.

Balor is written in Python and provides a set of command line tools aimed at engineering applications of your engraver, although still supporting regular laser marking as well. You can download the program from the project’s GitLab repository. He’s running it on Linux, but it should work on Mac and Windows (let him know if you have any portability issues). Check out our write-up from last year about using these lasers to make PCBs. Are you using a laser engraver to make rapid prototype boards in your shop? Tell us about your setup in the comments.

Laser Focus Made Easier With IR Filter

If you’ve used a diode laser engraver or cutter, you know that focus is critical. You’d think it would be relatively simple to get a sharp focus, but it isn’t that simple. [Makers Mashup] shows in a video how to use an adjustable IR filter to cut out all the light bleed to get a sharp image to make focusing simpler.

The filter he shows adjusts from 530nm to 750nm and is made to screw into a 72mm lens, but it works fine with your eyeballs, too. [Makers Mashup] says he’ll eventually make a stand for it so he can look through it with both hands free.

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