How to Use a Laser Cutter: Hobbyist Guide

How to Use a Laser Cutter: Hobbyist Guide

How to Use a Laser Cutter: Hobbyist Guide

Laser cutting is a non-conventional machining technique that uses a high-energy laser to bring your ideas to life.

However, using a laser cutter to produce intricate cuts with a high surface finish can be quite challenging for beginners.

Moreover, operating a laser without proper precautions can be dangerous, and a proper guide is required to make things easy.

The process of using a laser cutter consists of selecting the suitable material, followed by preparing the design, and performing test runs to find the optimal parameters before executing the actual cut. Apart from this, regular maintenance of the laser cutter plays an important role in producing high-quality results.

This article provides a detailed guide about the operation of a CNC laser cutting machine and the things required to get started.

How to Use a CNC Laser Cutting Machine?

A laser cutting machine works by focusing a high-energy laser beam on the surface of the material to vaporize, and produce the required cut.

CNC laser cutter is an automated machine that takes the design and parameters as the input and produces the desired output.

Perfecting the results on a CNC laser cutter requires some hands-on experience as every material behaves differently when processed under a laser.

However, the basic steps involved in every laser cutting process remains the same.

Preparing the Design

Preparing the design in LightBurn
Preparing the design in LightBurn

Preparing the design is one of the most important step in laser cutting as it replicates the final output in a digital file.

A good design should replicate the final output and ensure that the product will maintain its structural integrity after being laser cut.

Generally, each element of the design should have a width greater than the thickness of the material being cut to maintain its structural integrity.

There are various laser engraver/cutter software and nesting software that can be used to prepare the design, optimize the design layout, and convert the design into G-codes.

You can also use free laser cut files that are readily available on various websites.

There are two techniques of material removal by a laser cutter, and therefore two types of design files: Raster and Vector.

Vector vs Raster
Vector vs Raster (Source: CorelDraw)

Raster

Raster is generally used for laser engraving and works in a similar way as a laser printer prints the ink on a piece of paper.

In this technique, the laser head starts engraving from the top or bottom of the engraving and follows a uniform left to right pattern on each line.

The laser works in a continuous on and off fashion that prints tiny dots on the surface of the material similar to the pixels in a JPEG or PNG image.

The number of dots per inch (DPI) determines the resolution of the engraving, and generally, the higher the resolution, the higher the quality of the engraving will be.

Vector

Vector is generally used for laser cutting but can also be used for engraving lines and patterns.

A vector image does not consist of pixels. Instead, it is made up of geometric curves and lines based on mathematical equations.

These images can be scaled easily without distorting the image.

In vector cutting, the laser does not necessarily start from the top or bottom but starts from a default or manually selected point in the design.

Instead of following the left to right pattern, it traces an entire curve or line (design element) and then moves to the next design element.

This enables to set the sequence for cutting the design elements, and generally, it is a good practice to ensure that the innermost element of the design is cut first.

Unlike raster engraving, which traces out the entire pattern, vector engraving/cutting traces the outline of the pattern, making it ideal for laser cutting.

Furthermore, when designing a vector file, it is recommended to maintain the thickness of the outline to around 0.001" (0.025mm) or less than the spot size of the laser.

Setting the Parameters

After preparing the design, the next important step in laser cutting is to set the process parameters.

These parameters play an important role in producing a good quality cut.

Setting the optimal parameters will result in a perfect quality cut with minimum cycle time.

Laser parameters (Source Instructables)
Laser parameters (Source: Instructables)

Power and Speed

Power and speed are the two main interdependent parameters of laser cutting that affect the quality of the cut.

Laser cutting with high power and low cutting speed can result in over-burning of the material, and using low power with high speed can result in an incomplete cut.

However, each material requires different power and speed settings. For example, laser cutting acrylic gives the best results with moderate laser power and slow cutting speed.

Whereas laser cutting metal requires high power with slow cutting speed, and laser cutting wood at this power and speed setting would probably result in a fire.

Therefore, a perfect balance between power and speed is important to make a good quality cut.

Frequency

Frequency is another important parameter that is used for vector cutting.

When performing a vector cut, the laser does not slice through the material like a continuous hot blade.

Instead, it directs pulses of laser towards the material. These laser pulses are so fast that the human eye perceives them as a continuous laser beam.

The frequency setting controls the number of laser pulses produced per second.

As the frequency increases, the energy transferred to the material also increases, which thereby increases the heat generated in the material.

Using high frequency for cutting flammable materials like wood and paper can result in excess heat generation and lead to fire hazards.

Similarly, when struggling with charred edges, lowering the frequency can sometimes improve the quality of the cut.

Generally, most laser cutters provide a frequency setting of 10-5000 pulses per inch (ppi).

Resolution

Raster engraving (Source Trotec)
Effect of resolution on raster engraving (Source: Trotec)

Resolution setting works similar to frequency and is generally used for raster engraving.

It determines the number of dots printed by the laser per inch during raster engraving.

Increasing the number of dots per inch results in a darker engraving with high contrast.

However, setting the resolution too high can result in a dark engraving at the cost of the sharpness of the design.

Generally, a resolution of around 600-800 dpi produces good results on most materials.

Air Assist

Laser head with air assit nozzle (Source fslaser)
Laser head with air assist nozzle (Source: fslaser)

Air assist uses pressurized air to blow the molten material out of the kerf.

It facilitates the laser in performing a clean-cut and enhances the cutting speed.

Furthermore, air assist protects the focusing lens by blowing the hot debris away from the lens.

Using air assist is strongly recommended for laser cutting, especially when cutting thick materials.

However, it is not recommended during laser engraving as the pressurized air blows the molten material, resulting in a sputter over the engraving surface.

Exhaust System

Exhaust duct connected to a laser cutter (Source: Instructables)
Exhaust system connected to a laser cutter (Source: Instructables)

Laser cutting of materials such as wood, plastics, leather, etc., generates heavy smoke, which degrades the quality of the cut and can result in smoke stains on the surface.

Furthermore, laser engraving certain plastics can generate harmful fumes that can be dangerous for the operator if inhaled.

A good exhaust system facilitates disposing of the smoke away from the workpiece to produce a clean-cut and protects the operator from harmful fumes.

Performing Test Runs

Test runs on cardboard (Source Fabacademy)
Test runs on cardboard (Source: Fabacademy)

The optimal parameters for laser cutting vary from one material to another and from one machine to another.

For example, the optimal parameters for laser cutting polypropylene can differ from the parameters for polycarbonate.

Although both belong to the family of plastics, they behave differently when processed under a laser.

Similarly, the optimal parameters for cutting a material on a particular laser cutter can be different from the optimal parameters of a same configuration laser cutter from another manufacturer.

Therefore, it is always advised to perform test runs before laser cutting the actual workpiece.

Test runs provide an understanding of how the material behaves under different parameter settings and helps you to attain the best quality cut on the actual workpiece.

Generally, it is recommended to perform test runs on a scrap material by cutting a grid of squares at different power, speed, and frequency settings.

Furthermore, you can also study the effect of air-assist and exhaust systems by turning them on and off during consecutive test runs.

Preparing the Workpiece

Applying masking tape on the surface of the workpiece (Source Exploratorium)
Applying masking tape on the surface of the workpiece (Source: Exploratorium)

After preparing the design and finding the optimal parameters for the material, you can start preparing the workpiece.

Cleaning the surface of the workpiece to remove any dust or dirt particles is considered a good practice as these particles can catch fire during laser cutting and affect the quality of the cut.

Rubbing alcohol is considered a good cleaning agent but is not recommended for materials such as wood and paper, as they can absorb the alcohol and result in a fire when processed under the laser.

Furthermore, when laser cutting materials such as wood and leather generate heavy smoke, it is advised to cover the surface of the material with masking tape to prevent smoke stains.

Placing the Workpiece on the Work Table

Honeycomb bed down-pins for holding the job (Source Glowforge Community)
Honeycomb bed down-pins for holding the job (Source: Glowforge Community)

After preparing the workpiece, its time to place the workpiece on the work table.

Place the workpiece on the work table and ensure that it lies in the working area of the cutter.

Almost every laser cutter provides a reference outline to depict the cut area.

Ensure that the cut area lies on the workpiece at the desired location.

Although laser cutting is non-contact machining that does not exert any mechanical force on the workpiece, it is recommended to hold the workpiece in place when laser cutting light and flexible materials.

There are various ways of holding the material on the work table, such as magnets, tape, clamps, weights, pins, etc.

The primary purpose of holding the workpiece is to ensure that it lays flat on the surface to produce the best results.

Furthermore, work holding also ensures that the workpiece does not deflect under the action of the high pressure applied by the air assist.

Focusing the Laser

Using the focusing tool to set the laser focus (Source Thunderlaser)
Using the focusing tool to set the laser focus (Source: Thunderlaser)

The laser focus affects the laser's spot size, which in turn affects the kerf width.

Generally, most commercial laser cutters have an autofocus feature that sets the optimal focus for producing a precise cut with a narrow kerf.

For laser cutters that do not have the auto-focus feature, the manufacturer provides a focusing tool to set the optimal focal point.

However, when engraving certain flammable materials, it is recommended to defocus the laser to attain a relatively larger spot size, reducing the energy density and preventing over-burning.

Start Cutting

After setting the parameters and focusing the laser, you can close the lid (for the enclosed laser cutter) and begin the process of laser cutting.

Although CNC laser cutting is an automated process, it is advised to monitor the cutting process to prevent any accidents.

Good knowledge about the safety features of your laser cutter can help you take control of the process in case of an emergency and prevent accidents.

Finishing & Inspecting the Results

After completing the cutting process, inspecting the results without moving the workpiece is recommended.

In case of an incomplete cut, performing another pass over the workpiece can help achieve a clean cut.

Once you get the desired cut, you can remove the workpiece from the work table and inspect the final result.

It must be noted that laser cutting of metals can render the workpiece hot enough to cause skin burns if touched with bare hands.

Generally, the cuts made by laser cutter are extremely precise and do not need any secondary machining to improve the surface finish.

However, it is advised to clean the workpiece with a brush to remove any debris or sputter from the surface of the workpiece.

Maintenance of The Laser Cutter

Maintainance of the laser optics (Source Epiloglaser)
Maintainance of the laser optics (Source: Epiloglaser)

Laser cutters require minimum maintenance, and regular cleaning of the focusing lens and other optics of the machine will improve the quality of the cut and enhance the life of the equipment.

It is recommended to use a lens cleaning paper or a cotton swab with a liquid cleaner to clean the focusing lens after completing every cut.

If you are using a CO2 laser, it is recommended to clean and adjust the mirrors of the laser delivery system once a week.

When cleaning the lens and mirrors of the laser cutter, it is advised to hold the lens cleaning paper in a round-tip holding tool such as plastic tweezers to minimize the risk of scratches.

What's Required for Laser Cutting

The versatile nature of the laser cutter and its ability to cut various materials with a quick cycle time has made it popular among large-scale businesses.

Moreover, the availability of small-size desktop and portable laser engravers at a budget-friendly price point is attracting DIY enthusiasts and small-scale businesses to add a laser cutter to their workshop.

However, getting started with laser cutting requires more than just a laser cutter.

Laser Cutter

The primary requirement to get started with laser cutting is to have a good laser cutter.

Although laser cutters are generally costly, you can look for some budget-friendly laser cutters that can cut and engrave thin materials.

Fiber lasers are comparatively more costly than CO2 and diode lasers but are ideal if metal cutting is your primary objective.

Having access to a MOPA fiber laser cutter can even provide the ability to perform color laser engravings on metals such as titanium, stainless steel, and aluminum.

However, if purchasing a new laser cutter does not fit your budget, you can always look for used laser cutters.

As CO2 lasers have been around longer than fiber lasers, there are better chances of finding a used CO2 laser for a cheap price than a used fiber laser.

Furthermore, if you occasionally require laser cutting and are not willing to spend on buying a laser cutter, you can always rely on outsourcing.

You can look around your area and search for laser cutter owners who provide laser cutting services at reasonable prices.

Apart from that, you can also contact some online businesses that provide laser cutting services and deliver the product to your doorstep.

Here are the websites of some popular online businesses that offer laser cutting services in the US.

Workpiece/Material

After having access to a laser cutter, it is important to know about the materials suitable for laser cutting and materials that are not recommended to be cut or engraved by a laser.

Almost all the materials can be cut and engraved by a laser, except for some PVC and vinyl-containing plastics that produce harmful fumes of chlorine gas and hydrochloric acid.

Laser cutting vinyl materials is not only dangerous for humans, but the corrosive nature of hydrochloric acid can also damage the laser cutter.

Furthermore, laser cutting reflective surfaces like mirrors can be challenging as they reflect the laser, resulting in loss of laser energy.

Check out these guides on laser cutting and engraving some popular materials.

MaterialLink to Guide
AcrylicLaser Cutting and Engraving Acrylic
AluminumLaser Cutting and Engraving Aluminum
LeatherLaser Cutting and Engraving Leather
PlasticLaser Cutting and Engraving Plastic
PolypropyleneLaser cutting polypropylene
BrassLaser Engraving Brass
Paper
Fabrics
Plywood

Laser Cutting Guides for different Materials

Laser Cutter/Engraver Software

LightBURN software
LightBURN (CAD/CAM) software

A CNC laser cutting machine takes the design as the input and performs the required cut by controlling the movement of the laser head over the material.

Therefore, a computer loaded with CAD/CAM software is needed to execute the laser cutting.

These softwares are used to prepare the design (CAD), convert the design into G-codes (CAM), and acts as an interface to interact with the laser cutter and control its parameters.

There are various free and paid laser cutter/engraver softwares available in the market.

While some softwares perform all the function, others require two separate software for CAD and CAM.

Safety Instructions/Manual

Laser Safety
Laser Safety

Before getting started with the laser cutting process, it is strongly recommended to read the safety instructions and be wary of the laser hazards, risks, and control measures.

Flammable materials like wood, plastics, fabrics, and paper should never be left unattended during the laser cutting as they can catch fire and cause fire hazard.

Furthermore, it is advised to wear proper safety glasses when operating the laser cutter, especially when laser cutting reflective materials like copper and aluminum without a safety enclosure.

Laser Cutter and its Applications

Wooden Artwork (Source: Etsy)
Laser- cut wooden artwork (Source: Etsy)

Laser cutter is a versatile tool used for cutting, engraving, or etching various materials.

It uses a powerful laser beam to burn, melt, and vaporize the material and produce the desired result.

The laser is passed through a focusing lens to converge into a tight spot.

This enables the laser cutter to perform intricate cuts with high precision and narrow kerf width.

Laser cutters are well known for their high processing speed and precision, making them ideal for large-scale industries.

The type of laser used in the laser cutter determines its material flexibility.

A CO2 is best suitable for cutting organic materials like wood, plastics, paper, fabrics, etc.

However, a high-powered CO2 laser can also be used for cutting metals except for some highly reflective ones, like copper, silver, and gold.

On the other hand, a fiber laser is recommended for cutting metals. The wavelength of a fiber laser is readily absorbed by metals and is, therefore, best suitable for sheet metal industries.

Although fiber laser can mark and etch some plastics, it is not suitable for cutting organic materials.

A detailed article about the difference between a CO2 laser and a fiber laser can be found here - Fiber Laser vs CO2 Laser.

Another type of laser that is used in laser cutters is the diode laser.

These lasers can be used to cut both metals and non-metals but are generally available in low-power options, making them suitable for cutting thin materials only.

Recent developments have introduced high-powered industrial diode lasers that can cut and engrave almost any material.

A detailed article about the difference between a fiber laser and a diode laser can be found here - Fiber Laser vs Diode Laser.

The introduction of CNC laser cutters has opened the doors for using a laser cutter for various applications.

Applications of a Laser Cutter

The ability to control and manipulate various parameters of a CNC laser cutter enables it to perform different processes on various materials.

Cutting

CNC Laser Cutting Machine
Laser Cutting Metal

The primary application of a laser cutter is to perform intricate cuts in different materials.

A CNC laser cutter can be used to perform through cuts in various materials like wood, plastics, metals, food, etc.

The cuts produced by laser cutter are precise with a smooth surface finish, making it ideal for cutting intricate patterns for applications such as manufacturing of dies and molds, jewelry, medical equipment, artwork, fabric cutting, etc.

Furthermore, the ability to automate the process with high repeatability index makes it ideal for large-scale manufacturing industries.

Engraving

Wood engraving in Muse 2D Vision
Laser engraving a photograph on wood (Source: fslaser)

The ability to control the process parameters of a CNC laser cutter makes it stand out from all the other machining techniques.

It enables a laser cutter to engrave the material without changing the cutting tool.

Generally, when compared to laser cutting, a lower power laser and a faster cutting speed are recommended for engraving the material.

Laser engraving uses the laser to remove layers of the material and produce a void of the desired shape without performing a through cut.

The major difference between a laser engraver and a laser cutter is the ability to perform through cuts in materials of various thicknesses.

Laser engraving is primarily used in applications that involve enhancing the beauty of a product.

It can be used to engrave a pattern or a design on almost any material. There are various profitable projects, such as laser engraving knives, that you can make using a laser engraver.

Furthermore, it is also used by artists and designers to engrave a photograph or a design to produce personalized artwork and clothing.

Marking

Laser Marking (Source Trotec)
Laser Marking (Source: Trotec)

Marking is yet another application of a CNC laser cutter that involves altering the top surface of the material to produce a permanent mark in the desired shape or pattern.

This process does not necessarily involve the removal of the material. Instead, the heat from the laser oxidizes the surface and produces the mark by decoloring the material.

Laser marking is generally used to print valuable information, bar codes, and QR codes on products.

In some cases, the laser melts the top surface of the material, and a laser marking ink is used to add contrast to the mark. This process is often known as Laser Etching.

Frequently Asked Questions (FAQ)

Can a laser cutter be used to cut glass?

Yes, a laser cutter can be used to cut glass. But glass has an extremely high melting point, making it challenging for low-powered lasers to cut glass. Generally, high-powered industrial CO2 lasers are recommended for laser cutting glass.

Can a laser cutter perform welding?

No, a laser cutter cannot perform welding. Laser welding is a different technique that requires a purpose built laser head suitable for welding operations. Using a laser cutter head for welding or a welding head for cutting will not produce the required results and is therefore not recommended.

Can we laser cut PVC and vinyl?

Yes, you can laser cut PVC and vinyl. But the fumes produced by laser cutting vinyl and PVC contain harmful chlorine gas that is toxic to humans. Furthermore, when in contact with the atmosphere, these chlorine fumes undergo a chemical reaction and produce hydrochloric acid, which can damage the laser cutter.
Therefore, it is strongly advised not to cut PVC and vinyl with a laser.

About John

Hey I'm John. I talk about CNCs and Power Tools at Mellowpine. I'm a CNC hobbyist who has been making CNCs and writing about CNCs for a while. I currently also work as a consultant for business owners and hobbyists setting up their own CNCs. If you have any questions related to CNC, I'd be happy to answer them. Reach me at john@mellowpine.com

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John

Hey I'm John. I talk about CNCs and Power Tools at Mellowpine. I'm a CNC hobbyist who has been making CNCs and writing about CNCs for a while. I currently also work as a consultant for business owners and hobbyists setting up their own CNCs. If you have any questions related to CNC, I'd be happy to answer them. Reach me at john@mellowpine.com

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