Looking for spare parts for your K40 laser machine? Check out Cloudray Laser!

The K40 laser machine is a awesome little product who makes it easy for hobby and semi-pro use to get going with laser cutting or engraving. It´s far from perfect and needs a hand to work as you intended. First reading should be the article about checking your machine – K40 electrical warnings – first setup.

K40 laser water cooling

Coolant tank
Depending on where you live, it might be a good option to have a bigger tank 15-25L or more. If you live in a hot climate, you need a bigger tank to keep the coolant colder for longer, a small tank will heat up quicker. Check out cooling upgrades below.
The included pump coming with the machine is good enough and will work as intended. Make sure the pump is at the bottom of the tank and return-hose below water level.
Optimum coolant temperature is below 22 Celsius. Anything above will slow down the regeneration-process inside the laser tube, where the gasses are recombined to new Co2. If this process slows down you are using more “power” out of the tube than it regenerates and you will get a tube dying on you prematurely. Read more about coolant types here
Cooling upgrades
This part could be a own article. But i keep it simple for this article. I would point at three types of cooling upgrades. 1: Radiator in the water loop, to cool the water with ambient temperatures. 2: Peltier cooler, very inefficient but does the job – to a certain limit 3: Gas powered coolers, dedicated coolers like CW5000 or DIY built from a refrigerator.

K40 laser exhaust

Sealing the machine
Smell from the machine is both annoying and might be dangerous depending on what you cut. Sealing the machine will help keeping the gasses inside the case and out the exhaust, this can be done with duct tape, hot glue or silicone to seal the openings and cracks in the machine.
Change the exhaust fan
The included fan is both dangerous and bad, it will partially do the work but there is much to do. Read this bigger article about exhaust fans.
Smoke assist
I coined this term a couple of years ago, to get a term that describes the work of fans inside the machine. Read more about smoke assist here and here.

K40 laser power supply

All electronic products have problems with heat, the more heat the lower the efficiency. Our K40 lasers has the same problems and the power supply is very sensitive.. To prolong your life on the PSU you can do a few fixes to help this out. 1: Add ventilation to the small compartment where the PSU is located. 2: Tilt your PSU, to draw ambient temp in to the fan on top. Tilt your K40 laser power supply.
Add extra PSU
Relieving the power supply from extra load is a approach you should have in mind every time adding anything to the machine. Never add lights or peripherals directly to the laser power supply. Install a extra PSU for all your needs. A old computer PSU will work fine! If you want, you can install a extra 24V PSU to run your controller board, taking even more load away from the laser power supply and minimizing the risk of anything going wrong. A power supply with 5V, 12V and 24V can be bought from Ebay, aliexpress and amazon for 30-50 USD.

K40 laser optics and mirrors

Change lens and mirrors
When delivered, most of the machines has the cheapest available mirrors and lens installed. Changing this up will gain you a lot. Both in cutting power and less power needed for cutting. Mirrors needed: 20mm MO or SI mirrors Lens needed: 12mm ZnSE, GAAS or GE mirror. Read more about mirrors and lenses here
Cleaning your optics are very important. When the mirrors get dirty the tend to allocate the energy and get hot. If your mirrors gets hot it is a sign that your mirrors are dirty. Read more about cleaning your K40 laser lens and mirrors here
Add a fan to the laser head
A small 40-50mm fan mounted on the laser head helps with keeping the smoke away from the lens so you dont need to clean it as often. Do not confuse this solution with a air assist.
Air assist
The air assist saga is a controversial one, i have written more detailed article about it Air assist on K40 laser machines The basic function is to keep the cut clear from smoke and debris to help out the beam evaporate the material when cutting or engraving.

Bed´s and jigs for the K40 laser machine

Change your bed
When the machine arrives, it´s often installed with a metal bed and a big clamp. The optimal focus for these machines are 50.8mm focal point. With the original bed, anything you put on top of the bed is out of focus, it´s actually inside the clamp. To use the full width of the machine you need to change your bed. Read more about upgrading your bed here
Why sax-lift tables are (often) bad
There is cheap lifts on ebay, aliexpress and similar you can buy that are attractive to use. Beware of this type of movable bed, they are often not tight in the joints making the bed wobble in all direction. As the focal point is very important you cannot have a bed shifting up-down with 2-5mm when you put anything on it. There is more premium ones that will work good, or you can DIY fix your cheap-o lift to tighten it up in the joints.
Jigs and edges
Jigs and edges will help your out aligning material, parts or products for cutting and/or engraving if you do a lot of series. A jig may be a piece you fit inside the machine with holes, and then drop in your 20 pencils inside these holes and opening your template changing the text to engrave. This is also good when doing double-sided engravings to get the engraving aligned on the piece. Read more here how to create your own jigs and templates

K40 laser controller boards

There is different solutions for the machines, with better control and handling and bigger options for settings and software to use with your K40. Here i list the most common upgrades.
This is a prepared kit to convert your K40 for use with LaserWeb4 and other Gcode-compatible softwares like Lightburn. This is by far the easiest upgrade with very similar results as the other ones. Seen to the price it´s #2 More details here: http://cohesion3d.com/
Lightobject DSP kit
This is a prepared kit to convert your K40 for use with a AWC DSP controller.. More details here: http://www.lightobject.com/X7-DSP-upgrade-kit-for-DK40-small-CO2-laser-machine-P942.aspx
Ramps 1.4 kit
This is actually a 3D-printer kit, but there is different firmwares focused on the K40 upgrade. I am still upgrading one of my machines, so i´ll add more information later. More details here: https://github.com/ExplodingLemur/presentations/wiki/K40-RAMPS-Conversion
The Smoothieboard is similar to Cohesion3D (smoothiebased). Read more about it here: http://smoothieware.org/laser-cutter-guide

K40 laser lights

Adding more lights to your machine is always a nice upgrade. More visibility and it looks good too. Use a external power supply and add LED-strips inside your machine of your liking. Adding them into the lid or under the Y-carriage will help a bit with blinding you when using the machine.

Your K40 machine suggestions

Do you have a upgrade, update or mod you want to share? Comment below!
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David Galvin

I have a new tube for my laser cutter now along with a new Cloudray laser power supply. My new PSU reads from left to right:
Laser, AC ground, AC, AC. There is a test button for the laser, then it continues with Laser control High, Laser control Low, Water protection, Ground, 0 to 5v input, 5v output and a cable connector with lights for Water protection and Laser. This connector has an attached meter with Water protection and Laser output. The old power supply reads: Laser, AC ground, AC, AC, a light, a test button, water protection, ground, K+, K-, Ground, In (?), 24V, Ground, 5v(?) and Laser 5v. I have changed the new power supply to a separate 24v source with about 6- watts. Just following the old “put the same lines in” doesn’t work, obviously. HELP!! I need to get these connectors sorted out! Oh, and I forgot to mention that the panel on my cutter has buttons to set the power. I may have bitten off a bit more than I can chew. I have a separate 12v supply for the temperature (it works) and a potentiometer for setting the laser. Can you help me with getting this monster up and running? Any help would be appreciated. Thanks a bunch.

David Galvin

I’ve finished upgrading my K40 laser cutter but when I turned it on the tube shot a laser beam but it didn’t exit the confines of the tube. It was a new tube, 60 Watt. I don’t want to believe it but it looks like the tube was bad. It played around the water exit of the tube. But never came on to the first mirror. Thoughts?


Hello, is a good idea to change focal lens from 50.8 to 38.1? what are the pron and cons? Is this safe for a machine life? And what will be different with cutting and engraving 3 and 4mm plywood?


My working desk on laser is mobile, i can move go and down but, i have a problem with cutting 4mm plywood. Sometimes some line are not cutted. And my questions is 38.1 more efective for cutting 3 and 4mm plywood Than 50.8


I just read that you say that 22C is the max temp for the tube – my question: how bad is it if I stick with the manual (up to 35)? I have my machine inside at 25C and I don’t really have a way to cool it further…


I’m interested about the bed’s and jigs links, but seems still disappeared. Any chance to have it again?

Ahhh..!! BTW, thanks for this page, it’s very helpul for me 🙂


Thanks a lot for your help.

I’ll wait for your new article 🙂


Article ever coming out?


It seems, that the links from the Bed´s and jigs section have been removed, could you add them again? 🙂 I couldn’t find the article on the site using the search function.

Brian Hornberger

Can you put a computer fan on the front of the k40 where there’s a hole to help with the smoke removal I should have mine by the end of the week can’t wait lots of things I would like to try Thanks for all the great posts Brian

Peter Plail

Not exactly an upgrade but a suggestion of what you can do with a dead machine. My first K40 died in a glorious blaze of violet light as the EHT from a cracked laser tube fount its way to earth! The price of a new machine compared with that of a replacement laser tube wasn’t that different so I went for a new machine. So what to do with the old one?
I volunteer at a local country park as a woodworker and there are sometimes requirements to engrave on slices of tree trunk which are too big to go inside the K40. So I took the mechanical parts out of the dead K40 and mounted them in an open frame, added the controller board and the power supply (with the EHT stuff stripped out) and mounted a 3.5W solid state (diode) laser in place of the final mirror assembly.
As there is no bottom to the frame the entire unit can now be stood on a plank and by adjusting the height of the laser diode housing to get the focus right, we can engrave logos and text direct onto our timber.


I just cut the bottom out of my machine and added an extension tube to the head to get the focus about right for doing large objects. Obviously care must be taken to prevent laser injury or fire so beware.

John Persson

What is the #1 controller upgrade in your opinion?

Geoff W

A great source of info, thanks.
What are your thoughts on the power sockets on the back of the machine? After the fan plug fell out for the third time I have removed them both & now plug bother the fan and the water pump into a separate wall socket, where the sockets were removed from gives more airflow to the psi.

Ian Dorney

Keep up the great work


Ian Dorney

That was a magninicent read thanks Hakan. As I have said to you earlier I am brand new to anything like this and have no idea even where to start so I am reading plenty then will try the software LOL I have no idea there either but I am enjoying reading all you info

Thanks again ian

Jonathan Lin

What is the recommended l/min for an air compressor for the legitimate air assist?


Can you give more details about the airpump HP?