Enhance Your K40 CO2 Laser: 3d printed nozzle head with air assist and laser crosshairs

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An air assist upgrade for a laser cutter, such as the K40 CO2 laser, is a vital enhancement that significantly improves the machine’s cutting and engraving capabilities. This upgrade involves installing an air assist nozzle that directs a constant stream of air onto the material being processed. The primary function of this air stream is to clear away smoke, debris, and combustible gases from the cutting area, which helps in achieving cleaner cuts and reduces the risk of fire.

Enhance Your K40 CO2 Laser: 3d printed nozzle head with air assist and laser crosshairs
Enhance Your K40 CO2 Laser: 3d printed nozzle head with air assist and laser crosshairs

The air assist system typically includes a small air compressor or an air pump that provides a continuous flow of air through a hose connected to a nozzle attached to the laser head. The nozzle is designed to focus the air stream directly at the point where the laser beam meets the material. This focused air flow is crucial because it prevents the accumulation of debris on the lens, which can degrade the quality of the cut and potentially damage the laser system.

Upgrading to air assist also allows for cutting thicker materials more effectively. By blowing the smoke away, the laser beam can penetrate deeper without interference, resulting in smoother edges and reducing the thermal effect on the surrounding material. This is particularly beneficial when working with flammable materials like wood or acrylic, as it minimizes burning and melting at the edges.

Additionally, it is advisable to include air adjustment to accommodate different types of materials and thicknesses, ensuring versatility across a wide range of projects. For example, more delicate materials might require a gentler airflow to avoid unwanted material displacement, while tougher materials might need higher air pressure to effectively remove debris.

Overall, an air assist upgrade is a cost-effective way to enhance the performance of a K40 CO2 laser cutter. It not only extends the life of the machine by keeping the lens clean and reducing mechanical wear but also expands the machine’s utility by improving cutting speed and quality. This makes it an essential upgrade for hobbyists and professionals alike who are looking to get the most out of their laser cutting equipment.

Commercial head with air assist upgrade

When considering an upgrade to a K40 CO2 laser cutter, one option is to purchase a laser head that already includes support for air assist. This can be a convenient solution as it integrates the air assist feature directly into the head, eliminating the need for additional modifications or attachments. However, it’s important to consider the implications of this setup on the overall working space of your machine.

If you want get the head showed with integrated air assist support K40 Laser CO2 Laser Head with air assist

With a pre-equipped air assist head, the design may extend beyond the dimensions of the original head, potentially reducing the usable work area. This reduction occurs because the new head might not sit as close to the edges of the cutting bed as the original. Particularly, if you do not modify or replace the base where the laser head mounts, you may find that the added components of the air assist head encroach on the cutting area.

Furthermore, when you install the air tube necessary for the air assist system, it typically connects to the side or back of the head, protruding outward. This can lead to a loss of about 2 to 3 centimeters in the direction of the tube connector, depending on your system’s specific configuration. This might seem minor, but every centimeter of working space in a compact machine like the K40 is valuable, especially when working with larger pieces of material.

Custom nozzle with air assist and laser crosshairs

A pre-equipped air assist head offers convenience and integrated functionality, it’s crucial to weigh these benefits against the potential decrease in working space. For those who prioritize maximizing the cutting area, considering a more customizable air assist setup or making additional modifications to accommodate the new head might be necessary to preserve the workspace.

Here is my design of a 3D-printed nozzle to apply to the standard head of the K40 Laser. I use 2 diodes to prevent the problem of lost center when the pieces have different thicknesses.

STL file of nozzle 

This simple solution use 3M screw to fix It to the head and the same size to block the laser diode for the crosshairs.

Here the screw Aliexpress Countersunk Head Screw - Aliexpress Pan Head Screw - Aliexpress nut

I use a typical 12mm 5v laser diode.

Laser diode AliExpress

The final result

Air compressor

Choosing the right air compressor for your K40 laser cutter can significantly enhance its air assist functionality without breaking the bank. For my setup, I selected one of the more affordable air compressors that still offers all the necessary power for effective operation. This compressor features a 6mm tube that has a 4mm inner diameter, allowing ample air flow. It also comes equipped with a regulator, which is essential for both powering the compressor on and off and for regulating the air flow according to the needs of different projects.

You can find here 30L/Min Air Assist Pump

Initially, I considered placing the compressor inside the laser cutter to save space. However, I soon realized that the vibrations from the compressor could potentially add unwanted noise to the laser cutting process, which could affect the precision of the cuts. To avoid this, I decided to position the compressor outside the machine. I used the designated hole at the back of the K40 laser to pass the air tube through. This setup not only eliminated the issue of noise but also kept the laser cutter more stable during operation.

The results of this upgrade were very satisfying. The air assist function worked flawlessly, clearing away smoke and debris efficiently, which resulted in cleaner and more precise cuts. The overall improvement in the machine’s performance confirmed that investing in a good quality, yet cost-effective, air compressor and setting it up properly was a worthwhile decision.

Cable chain

It’s best practice to add a cable chain to prevent the cable from hanging from some base element. I found a very good project on Thingiverse, but it was too rigid for me, so I remixed it to make it simpler to manage.

End cable chain hodler 

Chain link 

Chain link end of bar 

STL file of nozzle 

And finally, the complete result.

Pipe and cable connection

Incorporating air assist into your K40 laser cutter is a straightforward process, thanks to a simple design feature. At the back of the laser unit, you’ll find a small hole specifically designed for this purpose. This is where the air compressor tube should be inserted. The tube channels a steady stream of air directly to the cutting area, which helps clear away smoke and debris, prevents flare-ups, and ensures a cleaner cut. This small but critical addition can significantly enhance the performance and safety of your laser cutting operations.

When setting up the laser diode for your K40 laser cutter, it’s important to connect the wire to the power supply correctly to ensure it functions as intended. On the power supply unit, you’ll notice there are two positions available for a 5V power connection. It’s advisable to use the middle position for this connection.

Remember, the 5V output can provide up to 500mA of current. Ensuring you do not exceed this limit is crucial to avoid overloading the circuit. This careful setup will power the laser diode effectively, allowing it to be a precise guide for your laser-cutting projects.


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