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Dec 13, 2023

Review: NEJE DK

When I got my first 3D printer I was excited, but now that I’m contemplating

When I got my first 3D printer I was excited, but now that I’m contemplating adding a forth to my collection, I have to come to the terms with the fact that these machines have all the novelty of a screwdriver at this point. Which is fine; getting the cost down and availability up is the key to turning a niche piece of technology into a mainstream tool, and the more people with 3D printers at home or in their workshop the better, as far as I’m concerned. But still, there's a certain thrill in exploring the cutting edge, and I’ve been looking for something new to get excited about as of late.

Lasers seem like an interesting next step in my quest towards complete in-house fabrication capability, so I started researching cheap setups to get my feet wet. In the course of looking up diode-powered laser cutters, I came across the NEJE DK-8-KZ. At only 1W, there's no question this device isn't going to be cutting a whole lot. In fact, it's specifically sold as an engraver. But given the fact that you can get one of these little guys for around $70 USD shipped, it's hard to complain.

Now I wasn't 100% sure what I would do with a laser engraver, but I thought it would be a good way to test the waters before putting serious money (and time) into something more powerful. Plus, if I’m being totally honest, I wanted to start on something on the lower end of the power spectrum because I’m terrified of blinding myself.

So what kind of laser do you get for $70? Let's find out…

Made of black laser-cut acrylic and held together with stainless steel cap screws, the DK-8-KZ has the look of something that was built from a kit but with good enough fit and finish that it doesn't feel cheap. Not to say it could be called substantial by any stretch of the imagination, as it stands just under 8 inches tall. On one hand that means it's convenient to toss up on the shelf when you aren't using it, but the reality of the DK-8-KZ's diminutive size is that it has an extremely small working area of approximately 40 mm x 40 mm.

There's an excellent reason the DK-8-KZ is limited to such a small and specific range of motion: both the X and Y axis of the device are riding on hardware reused from optical drives. I get the impression that a warehouse full of largely-obsolete optical drives was found in China, and somebody had the brilliant idea of using their accurate motion as the basis for a whole line of tiny laser engravers. (Editor's Note: we tried to find the earliest occurrence of such a device on Hackaday, and came up with this machine. See if you can find something older!)

The NEJE DK-8-KZ does come with a disc that has drivers and software for the device, but I promptly threw that in the trash. For one, I wouldn't trust the pack-in software with this device any farther than I could throw it. But more practically speaking, I don't have a Windows computer anymore so it wouldn't have done me any good. Luckily, the NEJE DK-8-KZ has a relatively simple control protocol and there are a few projects out there to get it up and running.

Personally, I’ve been using EZGraver and have had excellent luck with it. It's open source and works on Linux, Windows, and OSX. It even has a command line interface if you don't want to use the Qt front-end.

The workflow is pretty simple with EZGraver. After connecting to the hardware, you load up a 512 x 512 black and white image and adjust the scale and rotation controls as necessary. There's also a setting for how long you want the laser to burn for, which becomes important when dealing with different materials. Once the preview looks good and your burn time is set, you upload the job to the NEJE DK-8-KZ and click "Start".

One thing I found interesting with the NEJE DK-8-KZ is that the computer doesn't directly control it. The image and the selected settings are uploaded into the machine, and after that you can disconnect the computer and use it un-tethered by simply hitting the red button on the top of the machine to start the burn.

I don't want to beat up the NEJE DK-8-KZ too bad, as it's very cheap, and you can assume that the experience isn't going to be perfect when you’re buying a product made of DVD drive carcasses. But there's still a few things that need mentioning if you decide to walk down this path.

First, powering the thing. There's a 5 V power barrel-type power connector on the side of the device, for which you need to provide your own AC adapter. But even if you’ve got that connected, the board needs its own 5 V over the USB connection. Long story short, even if you aren't using the NEJE DK-8-KZ connected to your computer, you need to have both ports powered. This isn't a huge deal with how common 5 V USB power adapters are (I’ve got a whole box of them), but seems pretty sloppy.

Probably the biggest issue I found with the NEJE DK-8-KZ is the quality of the optics. You need to manually focus the laser onto the object you’re working on, as the focal point needs to be as tight as possible to get a good burn. The only problem is that the focusing lens dances all over the place when you turn it. There's no way to bring the laser into focus without the focal point drifting around, which means doing something as simple as pausing a burn to adjust the focus becomes effectively impossible.

Lastly, while it isn't a huge deal, I have to bring up how they handled homing the laser. There's no end-stop switches as you might expect, and instead the firmware simply runs the motors backwards for 20 seconds or so; making a terrible grinding noise every time you turn it on.

Of course, the real question with something like is how well does it actually burn. As it turns out, quite well. I’ve burned paper, cardboard, wood, and plastic with excellent results. It can easily cut through paper and 3M painter's tape, which holds some interesting possibilities in terms of making stencils for painting and etching.

If you’re reading Hackaday you probably want to know if you can use the NEJE DK-8-KZ to make PCBs. In the past we’ve shown somebody using a very similar device with pre-sensitized photoresist PCBs, so that should work well enough.

But what if you just have some regular copper clad board? I tried spraying a scrap of board with black paint, but the laser doesn't seem strong enough to ablate it away fully. I had much better results using black nail polish, but still haven't quite found the proper settings to get a clean burn all the way through. When viewed under a microscope you can see that the laser isn't completely removing the nail polish, which has hindered my attempts at etching so far.

I haven't given up yet. The trick might be multiple passes with the laser, or even some kind of abrasive or brushing after burning the board to knock off the last little bits of nail polish. I plan on keeping at this, and will post an update if I manage to get some good boards out of the NEJE DK-8-KZ.

The NEJE DK-8-KZ is such an old hack that if somebody sent it into the tip line as their own project, we’d ask ourselves if we wanted to run yet another CD-sled CNC machine. (Sure, we would!) That's not meant to knock it — honestly I’m impressed at what NEJE managed to do with what is essentially e-waste. Turning a dirty hack like that into a product is worth at least a hat-tip, if not a few Jolly Wrenchers. It isn't perfect, but once you get used to the quirks the results speak for themselves.

This thing isn't nearly as good as other "cheap" lasers out there, and it doesn't hold a candle to something like the K40. But for $70, I think it's a pretty great buy. It's unlikely to be your last laser, but it's a great choice for your first one.