K40 Laser Cutter Intro: A Great Little Machine

In a previous post, Workshop Journal #1 Good Tips for Making A Great Start, there was mention of an unspecified machine that was being set up and commissioned in the workshop. It can finally be revealed that particular “piece of equipment” is a humble and practical K40 laser cutter. 

Intro

k40 laser cutter in all it glory
K40 CO2 Laser Cutter

The little desk top CO2 lasers in the blue and grey box are hugely popular among hobbyist and makers alike. While limited in the size, thickness, and type of material they can cut, they have a range of applications for those with aneed for flat form material removal manufacturing.

The design is uncomplicated to say the least, it’s a sheet metal box with a hinged lid, a CO2 laser tube rated at a peak of 40W of cutting power, and series of mirrors aimed at a 2 axis moving head. Typical cutting area for a K40 is approximately 35cm by 23cm, slightly more than an A4 or US letter sheet of paper.

While there is nothing overly spectacular about the design or components, there’s nothing spectacular about the price either. This one was only around AU$500 (approx. US$350) and for that there’s enough kit to start cutting straight away.  

Cheap and Cheerful

A safe assumption is that much of the manufacturing cost for a K40 laser cutter is in the laser tube itself. While it may only be atiny 40W tube, it is still a relatively complex part. With sealed CO2 plenums, glass spirals, water jacket, and electronics, it’s a truly complex part that would have required many different processes during manufacturing. The cost of which would have been relatively expensive. In order to still sell the machine cheap, manufacturing costs would have had to be cut back in other areas, and it would seem those cutbacks have been made with every other component on the K40.

The K40 laser cutter, having just been removed from its packaging and still wrapped in cling wrap.
The K40, having just been removed from its packaging and still wrapped in cling wrap.

The sheet metal is thin as is the blue and grey paint; electronics are of low-end quality as is the honky-tonk control panel and push buttons; there is no fancy liner bearing or v-slot bearing system like you’d find on a 3D printer (instead a set of steel tubes with little nylon rollers); and the flexible ducting for ventilation is a joke to say the least. The manufacturer has put the money into the most important part on the machine – the laser tube. Everything else has been made super cheap.

Rear view of the 40w CO2 laser tube mounted at the back of the K40 laser cutter
Rear view of the 40w CO2 laser tube mounted at the back of the K40

This is not a complaint however, it’s simply an observation that this laser isn’t built to the same quality as some other desktop machines. For example, Creality’s Ender 3 Pro 3D printer is far superior in hardware quality, even though it’s cheaper with many more components. As the components are so cheap (and nasty in some areas) there is loads of potential to be unlocked by upgrading and swapping out parts. 

A machine for go, not just for show

Detail of some of the warning stickers on the laser tube at the back of the K40 laser cutter
Detail of some of the warning stickers on the laser tube

This piece of equipment isn’t simply a novelty, instead it serves a valuable, indented purpose. 3D printers are great and all, but they do have their limitations and there are areas where lasers are simply superior.  

While a 3D printer is capable of printing flat parts, a cover for electronics or the lid of a box for example, a laser is simply better suited to this application. Cutting from a single piece of material will yield a higher quality part, while taking a fraction of the time. 

The intention is not to replace a 3D printer with a laser, but rather have the two work in tandem, with parts produced on the K40 complementing parts produced on a 3D printer. The idea being that the printer will make the more complex and detailed parts, and the laser will do the simpler two dimensional parts. These can all be joined, attached or bolted to each other.

This brain wave came while designing a replacement for the RaspberryPi case originally made on the (now sold) Geeetech i3 Pro B. While the printer did the original case and could do the job of making a replacement case, time and quality could be dramatically improved if the top and bottom of the case were laser cut from acrylic rather than printed in PLA. If it could do so for this Pi case, then there would be numerous other additional applications it could be used for.

Proof is in the final product. A clear acrylic top with 3D printed base and hex stand-offs holding it all together. The final product is the combination of all these elements coming together to create a professional looking item.

Using the K40 Laser Cutter

Out of the box, the laser is more than capable. Plug it in, connect it to a computer and away it goes. This was a nice change from the usual battling with 3D printers that depend on constant user intervention, slight adjustments, and minute changes to machine settings. The K40 by contrast started cutting with little fuss or effort right from the moment of pressing the go button. 

Cutting a piece from acrylic on the K40 Laser Cutter
Cutting a piece from acrylic

Of course, after the initial cuts there was some tweaking necessary on the adjustment of the power output for the laser to get the cutting consistency right for the material. This is done by a rotary dial on the control panel of the laser, which regulates the current being applied to the laser tube while being energised, with an analogue ammeter giving a live reading of the current in milliamps at that given moment. It is an accurate way of determining what value of current needs to be applied for the material type and its thickness. Other K40 laser cutter variants have a digital percentage dial which doesn’t give as accurate a read out compared to the analogue dial.

Control panel on the K40 laser cutter
Control panel ont the K40 with an analogue ammeter for laser current

Even though this is only a wimpy 40W machine, there is still enough energy from the laser to melt plastic and burn timber if too much power is applied. I was too conservative to begin with, not allowing for enough power to cut through the material, eventually finding a sweet spot for etching and cutting with two or three passes on timber and plastic. 

Software

A CD with uninspiring software is included with the purchase of a K40 laser cutter. I followed the example of every other K40 user and swiftly showed this CD the inside of a garbage bin.

The go-to choice of software is K40 Whisperer. The Whisperer software is simple, efficient, and simply works – a bit like the laser it is controlling. While the user interface is basic and the program lacking more in-depth features, it will do 95% of what is required, including simple nesting for cutting, etching, and raster engraving. 

Another software alternative is Lightburn. While there is a free 30 day trial, a licence will need to be purchased after this grace period. Happily, the cost of a licence is reasonable at only US$162 (DSP license) so won’t break the bank, and once purchased it’s good for life. It’s definitely a step up from K40 Whisperer, with the more advanced features and settings that Whisperer is so desperately lacking. However, something to consider is that Lightburn doesn’t support the standard M2 Nano control board in a K40. For it to work therefore, the controller will have to be upgraded to utilise this paid software.

Is paying for Lightburn worth it over the free, K40 Whisperer software? Yes and no. Yes, because it is a professional piece of software, is more refined and has many more options and features available. And no because K40 Whisperer will pretty much do everything you need on a K40, and it’s free, and will work on the stock machine.

Modifying a K40 Laser Cutter

3D printed air assist with pneumatic tubing and nozzle directing air flow onto cutting surface
3D printed air assist with pneumatic tubing and nozzle directing air flow onto cutting surface

If what is being posted online is anything to go by, the majority of K40 users will modify their machines. It’s not surprising given how much low hanging fruit there is on this machine, there are loads of easy and inexpensive ways to upgrade the rubbish parts and make it into something decent, something that could be considered close to acceptable quality. 

While there is no requirement to modify, one upgrade that is considered a must is an air assist system. This set-up directs a stream of high velocity air at the point of cutting. This blows smoke or any small particles produced away from the cutting area and, most critically, away from the glass lenses in the tool head. 

Components used for the air assist system, air pump, pneumatic tubing and nozzle adaptor
Components used for the air assist system

Air assist is the first and, so far, only modification that has been made to my K40 (at time of publishing). Comprising a 3D printed nozzle and a high-capacity aerator from a fish tank, it does what it needs to do at a basic level. The nozzle adapter is of my own design with definite room for improvement. It will no doubt be altered and adapted as the machine develops and usage requirements change in time. My set-up is a good starting point and is so important to have on a K40, and is preferable to not having such a system in place. For future air assist systems, a better air pump will be needed to force even more air onto the cutting surface. And most certainly, air assist won’t be the last mod.

Conclusion

A handful of the initial pieces cuts from acrylic cut on the K40 laser cutter
A handful of the initial pieces cuts from acrylic

There is much to like about a K40 laser even in its stock form and even with its wonky quality. Regardless of this, it’s definitely worth what little money has to be outlaid to buy it. Having it is a wonderful addition to the workshop and itwill be relied upon for many projects going forward. Without a doubt, some of those upcoming projects are directly related to this machine and making it a bit less crappy quality. But for now, it’ll be fine just the way it is, in its stock configuration and with a fish tank air pump.


If you have enjoyed reading this article please share with your friends and followers on social media! while you’re there don’t forget to follow me, RB42, on Twitter, Instagram, Facebook and Pinterest for updates and new releases. 

Baden Jones
Baden Jones

Automation electrician by day, blogger at night – Captivated by technology and always busy tinkering away on something in the workshop.

Leave a Reply