Upgrades & improvements on the K40

The K40 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 – read it here.

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.


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.

Power supply


All electronic products have problems with heat, the more heat the lower the efficiency. Our K40 lasers has the same problems.
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. See article here.

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.

Optics and mirrors

Change lens and mirrors

When delivered, most of the machines has the cheapest availible 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 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 here
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

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

Machine 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.

Cohesion3D Mini

This is a prepared kit to convert your K40 for use with LaserWeb4 and other Gcode-compatible softwares.
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/cohesion3d-mini-laser-upgrade-bundle/

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


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 suggestions

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

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HP Persson

Digging up the strange ideas and convert them into useful tools and addons for the lasers.
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3 thoughts on “Upgrades & improvements on the K40

  1. 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

  2. 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.

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