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Jan 18, 2024

Hands On With The Ortur Laser Cutter

I couldn’t write very much without a computer. Early in my career, I wrote with

I couldn't write very much without a computer. Early in my career, I wrote with a typewriter. Unless you are pretty close to perfect — I’m not — it is very frustrating to make edits on typewritten stuff. The equivalent in the real world, for me, has been 3D printers and CNC machines. I can visualize a lot of things that I’m not careful enough to build with normal tools. Despite my 7th-grade shop teacher's best efforts, everything I did turned out to be a toothpick or a number 7. But I can get my ideas into CAD and from there the machines do the rest. That's why I was excited to get a laser cutter this past Christmas. You might wonder why I’d need a laser cutter if I have the other tools. Then again, if you read Hackaday, you probably don't need me to explain why you need a new gadget. I’ve had my eye on a laser for a good long time, but recent developments made it more attractive. I thought I’d share with you some of what I’ve found getting started with the Ortur laser cutter. The cutter is easy to put together and costs somewhere in the $200-$400 range depending on what you get with it. I thought I’d take some time to share what I’ve learned about it.

If you haven't had experience with a laser cutter or engraver before, you might think it is a very specific instrument. Sure, the Ortur is good at engraving some things (but not all things). It can cut some things, too, but not as many things as a big serious laser cutter. However, creative people find lots of ways to use cutting and engraving to produce things you might not expect.

For example, if you surf YouTube, you’ll find people who put spray paint on either a ceramic tile or a canvas and then burn some or all of the paint away to make really interesting artwork. Sometimes they’ll even use multiple layers of paint to create different colors by burning different depths into the artwork. Another multicolor technique is to cut what amounts to a custom stencil in masking tape that is already applied to the part. You can then spray paint, remove the tape, apply fresh tape, and cut a new stencil for another color. Some people etch the backs of mirrors. It is also surprisingly handy to be able to precision cut paper and cardboard. However, with some practice and technique, you can even cut some thicknesses of plywood.

I’m very interested in creating PC boards either directly or by cutting resist and then using conventional etching techniques. People are doing that, too. Depending on the power of your laser, you can cut quite a few things, although with a visible laser, you can't cut things that are transparent. You can engrave more things, and even metal if you use some additional chemicals (like mustard). In addition to line art and text, you can do halftone images from pictures. If you have a powerful enough laser, you can even make glass, sort of.

Of course, in addition to all the artsy things, you can just cut material too, which is surprisingly handy. [Electronoobs] did a video last year experimenting with different materials with a 15W laser so that will give you some idea of what you can and can't cut with this type of laser.

There are some things you shouldn't cut because they emit noxious fumes like ABS or vinyl products. Leather engraves and cuts well but boy does it stink! I understand that you should be careful working with chrome tanned leather, too, because the tanning chemicals could emit bad fumes. Some materials are also too prone to bursting into flames like styrofoam.

If you want a laser, your next problem is which one to buy. There are carbon dioxide lasers that are commonly available, but they are pretty pricey and are known to need a lot of effort — including a bucket of ice of water and ventilation — to use. Semiconductor lasers are cheap and much easier to use. These are generally visible which, as I mentioned, means you can't use them to cut some things like clear acrylic. You can get some very inexpensive laser engravers, but many of them are probably not going to cut much.

Then again, power isn't everything. Broadly speaking, you can trade time for power with a laser. That is, a cut that might take a 10 watt laser a few seconds in a single pass might take a 1 watt laser four or five 30-second passes. It isn't always simple because as the laser chars material it creates a barrier that prevents you from getting as much energy underneath. Still, you can sometimes do the same job with lower power if you are willing to take longer per pass and repeat the pass.

The Ortur Laser Master 2 is reasonably priced and has three choices in laser power: 7W, 15W, and 20W. This is a little deceptive because the power is actually the input power to the module. The 15W unit, for example, produces less than 5W of output power, but that's still able to do a lot more than you might think.

The device is made to work with a free piece of Windows software called LaserGRBL that talks to the onboard GRBL controller. In theory, anything that would send G-code could work. I use Linux, so I opted for LightBurn which is excellent and well worth the $40 you’ll pay for it. It runs on multiple platforms, too, but sadly not on the Raspberry Pi, so I’ve had to drag a laptop out to work with the Ortur. You might also check out LaserWeb.

There are other cheap laser engravers and cutters, but I was impressed with the Ortur's size and capabilities. There's also a lot of add on designs available for it and good support in software.

The unit requires some assembly, although much of it is preassembled. You build a frame of aluminum extrusions and then slip the X carriage on. There's a 32-bit controller board and some stepper motors. The 32-bit board is a big selling point. Some of the work you do with the laser requires PWM to modulate the beam's power. Most 8-bit boards will allow you to step power from 0-255 so each step is about 0.4% of full strength. A 32-bit board will let you do around 1,000 divisions of full scale which gives you about 0.1% on each step.

The mechanism is like a plotter or a 3D printer with no Z-axis. Since the laser doesn't touch anything, it doesn't need the robustness of a CNC setup. Of course, you can also mount a laser to a 3D printer or a CNC machine if you already have one and that's not necessarily a bad option, although most of those setups have some limitations (for example, no modulation of beam intensity).

The best way to see how to build the machine is to watch the company's video instructions (see below). There are a few things unclear in the video and I made some notes that might help you. There are also plenty of 3rd party build videos on YouTube.

The urge to cut something is overwhelming when you get the unit complete. However, be sure you have eye protection and plenty of ventilation. You should probably have a spray bottle of water and a fire extinguisher, too (you can see one of my fire extinguishers in the video below). Things do catch on fire under a laser, so be prepared. If you do get a little flame, try the water first since the extinguisher will make a huge mess.

The glasses that come with the cutter seem to be adequate and some people have tested them by firing the laser through them. However, I opted for some better-quality glasses. Your eyes are worth more than a few bucks you can save with cheap glasses.

Be sure you have the latest firmware. My unit predated the January 2021 update and the fan did not run unless the laser was also running. I would guess this would shorten the laser diode's life. With the updated firmware, there is smarter fan management along with some other fixes. The update is as simple as dragging and dropping a file, but for some reason, it only works under Windows. Linux sees the USB drive and will do the copy but it doesn't stick. At least it didn't brick the cutter.

Regardless of firmware, before you can cut, you’ll need to set the focus correctly. If you are like me, you are probably thinking: "Focus? You don't focus a laser." Well, turns out you do focus a cheap laser.

To get the required energy to the workpiece, the semiconductor laser passes through a lens that focuses the beam to — more or less — a point. That point is what does all the cutting or engraving. That means the piece you want to work with has to be at that focal point. After the lens, the beam will look like an hourglass and the further you are from the pinch in the hourglass, the less cutting you’ll do.

The Ortur's laser doesn't move up and down but the lens can either screw in and out a few millimeters or push in and out, depending on which one you have. Once you have something under the cutter, you can put some black construction paper over it and use that to visualize the focus. The software you are using will have a button to turn the laser on at low power. Using the glasses will help reduce the spillover and you’ll be able to see the main part of the beam easily on the black paper.

Some people use a USB microscope or other magnification to get the best focus. However, I didn't like the stock method for focusing. The lens ring is hard to turn and even if you 3D print your own ring, it is awkward to spin the lens around. It also doesn't afford you much range.

Luckily, there are many 3D printed solutions to create a moving laser head on the Ortur. I’ll show you the one I’m using next time. For now, assume you are going to focus the lens yourself. That limits the height of things you can cut or engrave, too, although some people put the machine on blocks to make more room underneath. A tight focus will let you cut or engrave quicker and make the cut line finer, too. However, even if you are a little off, you can usually get some result. It is a good idea to tape your work down or clamp it so if you need to you can do a second pass without moving anything.

There are different lenses you can get for the laser. The one the 15W machine comes with has a focal length of about 55 mm. However, there are other lenses — the G8 is popular — that have different focal lengths. Each lens has different characteristics as far as how tight they can focus and how many elements they have (more elements means less overall power).

The power delivered to your part is a combination of the beam power, the quality of the focus, and the time spent. Even the time it takes for the laser to change direction can cause a deeper burn or cut which is why most software offers an overscan function that keeps the laser off and away from the cut line when it changes direction.

If you are careful about focusing, you should be able to get a pretty good engraving on a piece of cardboard. Be sure to have something under it since you might cut through and leave a permanent mark. I mounted my cutter on a piece of plywood and I deliberately marked a grid on the board. I’ll tell you more about those additions next time.

Sometimes, you deliberately want to defocus a little to get wider lines. [Geordie_h] talks about this trick, along with some other pro tips that are aimed for a more commercial cutter, but still apply to the Ortur and other similar lasers.

Speaking of next time, there's a lot more to talk about. In addition to mounting the device and making the laser head move, I wanted to add air assist — something I’m still working on. This clear smoke from the cut as well as fine ash, allowing the laser to hit fresh material while cutting.

For some reason my machine will often stall on long cuts, and from reading the Internet, I’m not alone. Changing USB cables seemed to help. It may need a slightly beefier power supply or grounding on the frame. Then again, it could be power settings on my laptop. Time will tell. This has been particularly a problem when doing images that require a lot of time. You can see my picture of Rocky has a little misalignment at the top where I restarted after a failure like this and didn't quite get it lined up right.

The Ortur reminds me of early 3D printers. It works, but it needs some work to get it to work well. But, for me at least, that's the fun part anyway.