Interesting Optics Make This Laser Engraver Fit In A Pocket

We’re going to start this post with a stern warning: building a laser engraver that can fit in your pocket is probably not a wise idea. Without any safety interlocks and made from lightweight components as it is, this thing could easily tip over and sear a retina before you’d even have time to react. You definitely should not build this, or even be in the same room with it. Got it?

Safety concerns aside, [DAZ] has taken a pretty neat approach to making this engraver, eschewing the traditional X-Y gantry design in favor of something more like the galvanometers used for laser projectors, albeit completely homebrew and much, much slower than commercial galvos. Built mostly of 3D-printed parts, the scanning head of this engraver uses a single mirror riding on an angled block attached to gimbals with two degrees of freedom. The laser module and mirror gimbals are mounted on a stand made of light aluminum so that the whole thing is suspended directly over a workpiece; the steppers slew the mirror to raster the beam across the workpiece and burn a design.

The video below shows it at work, and again, we have to stress that this is about as close to this build as you should get. It shouldn’t be too hard to add some safety features, though — at a minimum, we’d like to see a tilt-switch that kills power if it’s knocked over, and maybe some kind of enclosure. Sure, that would probably spoil the pocketability of the engraver, but is that really a feature valuable enough to risk your eyesight for?

If there’s a laser build in your future, please read our handy guide to homebrew laser cutter safety — before you can’t.

35 thoughts on “Interesting Optics Make This Laser Engraver Fit In A Pocket

  1. Can we at least agree that pictures of laser engravers should always contain a pair of requisite laser safety goggles? They should rather be worn than sit around in the shot, but without them I feel there’s some visual communication lacking.

    1. I can’t remember a time when I picked up some matches and they had warnings not to use them near flammable fuels.

      The stove in my kitchen does not have a sign on it that says “do not attempt to cook anything containing gasoline”

      Last time I bought a screw driver it did not come with a warning saying using a screw drivers increases my chances of going blind (who knows, someone could try using a screwdriver to remove an eyelash from an eye?)

      Oh, but we do have “Contents are very hot” in paper coffee cups…

      1. This comment speaks to how well McDonald’s PR department handled that case to get you parroting their spin. You should read more about the things you reference instead of trying to demonstrate gruffness in a comment section.

        Stop being so offended by warning labels that you whine about them. Peel them off your devices if you’re still red faced about them.

        1. By nature, coffee can be no hotter than 100°C at ambient pressure. It was a frivolous lawsuit; she could have just as easily spilled her own coffee at home and not gotten paid for it. If anything, that case is an argument against privatized healthcare, not McDonalds.

          1. The fact is that there were dozens of McDonald’s customers burned severely before the one you don’t care about. She originally asked for a few thousand dollars for medical care.

            At the time 90% of cars had no cup holders. The McDonald’s cups were softened by the heat and lost 90% or so of their structural integrity when the lid was removed. So, no, she could not just as easily have spilled her own coffee at home.

            She was paid for 3rd degree burns – look at the pictures of the damage done to her. AFAIK the jury held her partly responsible, but the majority of the blame belongs to McDonald’s.

            McDonald’s put up a big “frivolous lawsuit” campaign to discourage other victims of their 20-30 degree hotter serving temperature coffee from also coming after them. The knew and knew and knew and hid that information from customers – not just that the coffee was hotter than people would drink at home or at other restaurants, but that the cups would fail if the lid was removed and not very carefully held in a particular way.

            McDonald’s changed to cups made of materials that didn’t soften in the heat and car makers now have many cup holders. Had McDonald’s used ceramic mugs she would have been fine. Had McDonald’s put the coffee in a tray to hold the cup upright – she would have been fine. McDonald’s knew exactly the cause of the problem and the customer could not have been aware of the defect. Sure, coffee is hot. How often are cups too flimsy for the application?

        2. I don’t think so: helge thinks we should all agree that every picture of a laser engraver should have a pair of goggles in it. His stance was extreme and ridiculous, so NENLAW’s comments extended the logic to other dangerous tools and appliances in common use to ask “Where does it end?”.

          (Basically, you missed the point. Also they weren’t complaining about warning labels, they were saying that there are plenty of dangerous items in regular use that don’t require warning labels. Instead the user is expected to practice caution and read the instructions, so there’s no need for every picture of a stove to contain an oven mitt.)

        3. Is it just McD’s PR causing people to say that a warning on hot coffee is redundant? In the case of McDonald’s, no amount of warning on that cup would have prevented the lady from getting third degree burns from their negligence when serving extraordinarily hot coffee. How many people have seen the warning on a coffee cup and heeded it solely because they read it? There are two truths here. McDonald’s was absolutely culpable for injuring that woman, and we as a culture seem to believe that society requires safety labels on almost everything. You can agree that woman was not at fault and also believe that only a dunce requires a warning label on their hot coffee.

        4. I didn’t even think about the McD’s coffee when I wrote that. But if I recall, the issue with tha case was not the cup not having a warning on it or the lady being an idiot, but that the coffee was kept, and thus served to customers, at an unreasonably extreme hot temperatures.

          In fact, McD’s had already been previously told that keeping it’s coffee at such temperatures could end up causing harm to someone. And it did.

          However, my point about the warning on the coffee cups is a different one. If you are going for a cup of coffee, unless you ask for a cold cup of brew, you KNOW it is going to be hot, and you’re not going to read the label and go, “ooops, better ask to put hismcup in a coozie or inside another paper cup, thank god I saw that warning label!”

          More directly related to the laser + safety glasses, showing a picture of safety glasses along with the laser does nothing with regards to laser safety. In fact I’d ask myself, why are they next to the laser and not on the users face? Then when one reads the story, all the way to the end, one finds a link to safety when playing with lasers.

          So yes, some labels exist only because of idiots. I’d even argue that a lot of labels exist only because of idiots who sue because a label was not found. Have you looked at the owners manual for a car recently? It is loaded with warnings, that clearly are meant just to be there for legal purposes. Who the hell does not know that one should proceed with caution when using a motor vehicle? That’s more of the point I was going for.

          1. I’ve heard a few additional details about that case. If they are true then yeah, the pro-McDonalds, anti-lawsuit spin we received from the media was pretty unwarranted.

            First, the McDonalds in question regularly prepared large containers of coffee for construction crews. These were required to be extra hot so that they would remain hot throughout the day. They couldn’t be bothered to keep two different machines at two different temperatures so every customer received extra-hot coffee.

            Second, the cups the coffee was served in weren’t really designed for that temperature. They became soft. So it really wasn’t just a matter of “any idiot should know that coffee is hot and take care accordingly”. It was an accident waiting to happen that one of those cups would collapse in a c̶u̶s̶t̶o̶m̶e̶r̶’s victim’s hand. In this case when it finally happened it happened to a lady in her car so it didn’t just get her hand but her lap and all the sensitive parts in that area too.

            So they were serving a hot liquid in a cup where the liquid was hotter than the cup was designed to safely contain. Sounds like a valid legal issue to me.

          2. @Twisty Plastic. McD’s had already had several complaints their coffee was too hot and meant for people to drink it right away when purchased as opposed to let it cool down and drink later.


            McDonald’s claimed that the reason for serving such hot coffee in its drive-through windows was that those who purchased the coffee typically were commuters who wanted to drive a distance with the coffee; the high initial temperature would keep the coffee hot during the trip.[13] However, it came to light that McDonald’s had carried out research finding that customers intend to consume the coffee immediately while driving.[22]

            Other documents obtained from McDonald’s showed that from 1982 to 1992 the company had received more than 700 reports of people burned by McDonald’s coffee to varying degrees of severity, and had settled claims arising from scalding injuries for more than $500,000.[13] McDonald’s quality control manager, Christopher Appleton, testified that this number of injuries was insufficient to cause the company to evaluate its practices. He argued that all foods hotter than 130 °F (54 °C) constituted a burn hazard, and that restaurants had more pressing dangers to worry about. The plaintiffs argued that Appleton conceded that McDonald’s coffee would burn the mouth and throat if consumed when served.[13][23]”

            You can read the whole thing in wikipedia https://en.wikipedia.org/wiki/Liebeck_v._McDonald%27s_Restaurants

      2. You screwdriver would not harm someone dozens of feet away, unless you intentionally throw it. And would not bounce behind your back because you have a reflective surface in front.

    1. That was my thought, but also including an exhaust fan to keep smoke off the mirror would make it a bit less pocketable.
      Now, why he would put a regular, silver backed, 2nd surface mirror when he could easily, with a little paint stripper, have a 1st surface mirror is beyond me.

        1. I don’t know how well it will work on every mirror but the back of the mirror usually has protective/opaque paint over the reflective layer than can be stripped off leaving just the shiny stuff.

          Seen it done, but never had reason to do so myself.

        2. Most household mirrors will have a protective coat of paint on the back covering the silver layer. Give the paint stripper plenty of time and you can remove most with just a hard stream of water. Any stubborn bits you gently remove with a soft cloth.

  2. I love it – I’d have one.

    Throw a box over it with an exhaust fan for the safety conscious and maybe a tilt swicth to cut the laser power should it topple over.

    1. Honestly if your machine is a blind-o-matic 17000 safety interlocks are a good idea. Especially when you’ve got people in the comments talking about how they’re totally unnecessary.

      It reminds me of reading IAEA incident reports.

    1. Doesn’t even matter if it will burn, it just has to resist long enough ideally while discoloring to prove your laser has been misaligned, the material backskatters badly (etc) and the tent now needs replacing. Bonus points if you weave a low melting temp metalised plastic thread through it or coat the inner surface with a conductive but easily burned dopant as a safety cut off – tent gets hit by much of the laser’s power for any length of time and it cuts that trace.

        1. I think that is also a valid approach, though I have to admit I have no idea how reflective those mylar sheets you can get are to all the wavelengths your laser may be on, it might just fail really quickly if it happens to be very good at absorbing that wavelength (I think they should be good for all the common wavelengths though I just don’t know for sure, and I don’t think its the easiest thing to really look up as those sheets seem to always be composite structures with no particular lamination materials reliably in use as the outer coatings – seems like they are often made ‘one sided’ as well, which may actually be a good thing for this application, but adds more variation).

          Then even if the mylar sheet does reflect really well so it won’t fail ever while exposed to this power of laser – so aught to keep an outside observer safe (which is great) I would think increases the chance of the machine damaging itself… Which may be the best thing for such a dangerous ‘toy’ laser machine…

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