K40 Lasers: Setting Up
I’m not sure if my K40 was the exception or the rule, but when it arrived, I found the sheer amount of hot glue adhered to it quite alarming. Under further inspection I realised it peeled off in a way that was actually quite satisfying once I’d reassured myself that it caused no detriment to the machine. This instalment of the K40 mini-series covers the initial laser set up in the hopes of helping you turn whatever hot glued mess arrives at your door into your new favourite tool. I will give an overview of each step I took, along with the tips and tricks I learnt along the way.
Unbox/Remove the hot glue
As I have said, there’s a lot of hot glue. Connectors are glued into their sockets to stop them falling out in transit and the mirrors are covered. This results in a repetitive analysis of each glue chunk as you decide if it can/should be removed. The only piece of hot glue I left behind held a thermocouple onto the electronics enclosure, everything else I peeled away (take particular care around the mirrors - they scratch easily). While extricating the laser from the glue, it is also wise to give it a good looking over. Check for loose wires, bent rails, cloudy mirrors, and broken laser tubes. This is the best point in the process to return a faulty laser if you need to. Once it reaches you it has likely travelled half way across the world on a boat - faulty K40s are quite common.Check Electronics
Before plugging anything in, give the electronics a good inspection. Ensure the connectors are seated correctly and that no wiring gets caught when the laser head moves. Crucially, check the case earthing. It’s very tempting to skip this but you’ll be glad you didn’t when you don’t electrocute yourself. Get a multimeter that can check continuity and follow this guide to make sure that the case is suitably earthed for your country.Laser Tube Cooling
Most K40s come with a pond pump and tubing. As per the first post, you will need to have sourced some sort of bucket and at least 5L of distilled water. Don’t be tempted to use tap water, it will go mouldy and ruin your laser tube. In the long term it is best to replace the pump with one that has a dedicated power source but to get you started the supplied pump is fine, just ensure the connector stays in the back of the machine. Mine can fall out with the machine vibrations so I secured it with some tape.Extraction
The machine comes with a fan and a small section of ducting which is insufficient for most needs. Ply, MDF and acrylic all give off harmful chemicals that are best extracted well. I recommend replacing the provided fan with better extraction. The original fan screws can be tricky to access for removal. I needed to take out the dust guard and the bed to reach them which is why I suggest replacing this system early on.Mirror Alignment
Unless you are incredibly lucky, the mirrors will not be aligned out of the box. This process can take a while so make sure you have some free time booked out, grab a drink, and hunker down. It took me around 4 hours in total. After a lot of research this webpage was the best resource I found and made the job relatively easy. This is also where I’d most recommend wearing laser safety glasses. Even if you close the lid every time you fire, I have heard horror stories of the laser escaping through small gaps in the casing. Another tip: put the laser on a low power (~7% should suffice) as you don’t need to cut through anything at this stage.Air Assist
This is often classed as optional but in my experience it’s not. The only time I cut without air assist there was a lot of flames. This only gets riskier in the long term. Installing a 3D printed nozzle makes for a great starter upgrade. When securing the nozzle to your laser head be sure that the head will still be able to move unhindered to all parts of your cutting area. The tubing will need to be fed out of the back of the case to connect to the compressor. I fixed my tubing into a good position inside the case using some well-placed tape – this method hasn’t failed me yet. If you have a 3D printer and many hours you could look at building a bigger cable chain but I haven't found this necessary.Software
You will need a computer to run the laser. Make sure you have installed the right software and drivers for your laser before you get started. Many K40s provide a USB with this on but I would recommend getting the latest versions online instead. What you install will depend on the control board in your laser. Boards from Lihuiyu (which is most of them) can use the standard K40 Whisperer software bundled with drivers. The installation is easy but check your driver board before downloading. You will need the software up and running to conduct the ramp method in the following step.Focusing
If you cut without knowing your focal length then chances are you won’t cut all the way through, or your clean lines will be too wide. I found that the ramp method gave a more reliable focal length than the manufacturers specifications and would recommend this to anyone setting up. Note that this is best done with the bed removed/very low. An accurate focal length is key when getting to know your machine. If you measure the focus to a fixed point on your laser then you will find it easy to check you’re working at the right height as you switch materials.Bed
For optimum results you want the focal length of the laser to be halfway through whatever material you are cutting. You will want to set the bed height accordingly. As per my first post I upgraded the provided laser bed using steel mesh, standoffs and a scissor jack. As the cutting material sits flat on top of the standoffs, I found it easiest to measure the focal height with the material in place on top of the bed. I tweaked the height of the scissor jack until the material height measured half its thickness above the focal length. The adjustability of this set up means it can be easily optimised for a variety of objects. If you scour the internet there are all sorts of ingenious DIY solutions for adjustable and level beds, this is just my version.Guide Dot
As everything else is now in place, you can finally line up any guide dots or lines your laser has. Put a piece of material on your bed at the correct height, shut the lid and tap the ‘test’ button. This will leave a dot which you can aim for as you adjust the positioning of your guides. Repeat until you get a result that you are satisfied with. This will be a case of trial and error as you iterate the position. I have found that the guide dot is susceptible to a little wandering even when it’s fixed so if you’re relying on this for an accurate position it is always good to check before you start.Designing
Now everything is set up you’ll need to create files for your work. I generally use Inkscape for this as it is free and the svg file format can be imported straight into K40 Whisperer. In your svg files red lines indicate cuts (hex code #FF0000), blue lines indicate vector engravings (hex code #0000FF) and greyscales are read as raster engravings. If choosing to use raster engrave be sure to enable dithering in the Whisperer software before you start.Maintenance, Settings and Cleaning
When I first started looking at lasers I spent a lot of time trying to find what power settings I needed to cut different thickness and materials. Whilst I’ll touch on this in the next post, I did come to learn that it was a very complex issue. It varies depending on the efficiency of your laser tube, the quality of your set-up and, crucially, the cleanliness of your mirrors and lens. Cleanliness changes over time (and even over the course of a print) as ablated material settles inside the laser. Good extraction helps minimise this but it is almost impossible to stop. I clean the mirrors daily and the lens monthly to help keep everything running smoothly. This is best done with isopropyl alcohol and a lint free wipe. It is very easy to scratch the optics so be gentle.
Now you’re good to go, the next post in this series will focus making things – where the fun really starts! I hope this round up has inspired some and helped others. I love to hear from you so let me know any thoughts or questions in the comments.
The following website is recommended for those interested in learning more. I, like many others, found it invaluable when first starting out: https://k40.se/k40-laser-setup/
Thanks for reading!
