About Us



Follow Us

Laser Not Cutting Like It Used To: How to Fix



Hey I'm Unni. I am a laser and CNC expert at Mellowpine. You can also find me on Mellowpine Lasers YouTube channel. If you have any questions related to CNCs or Lasers, I'd be happy to answer them. Reach me at mail@mellowpine.com


Laser not cutting like it used to

Do you feel your laser is not performing like it used to when you first got it?

Well, there are a couple of reasons that can make lasers less effective over time.

I’m Unni, and I’m a laser engraving expert. In this guide, I will explain the possible reasons for the deteriorated performance of your laser and how you can get it back to its original potential.

Top Two Reasons Why this Happens

If you feel like your laser is losing its power, it is not necessary that there is something wrong with your laser source.

There are a couple of reasons that can degrade the performance of a laser.

1. Dirty Focusing Lens- Maintenance Issue

Cleaning the lens of a diode laser
Cleaning the lens of a diode laser

The most common reason for a laser losing its power is a dirty focusing lens or dirty focusing mirrors in a CO2 laser.

This generally happens due to the smoke and fumes generated during the laser cutting and engraving, which gets deposited on the lens.

This smoke smudges the lens and degrades its ability to focus the laser properly, leading to a loss of power in the poorly focused beam.

Apart from reducing the ability of the laser, this can also damage the lens as the laser can burn the accumulated dust and grime and melt or crack the focusing lens.

How do you Prevent the Lens from Getting Dirty?

To avoid this issue, always clean your laser lens after every 5-8 hours of operation.

If you are working with materials like MDF and wood that produce heavy smoke during laser cutting or engraving, then it is advised to clean the lens every 2-3 runs.

Apart from that, using an air assist will blow the smoke away from the lens, minimizing the accumulation of smoke and thereby reducing the need to clean the lens frequently.

While it is advised to use air assist only during laser cutting, if your setup allows you to control the air pressure, then it is recommended to use a low-pressure air assist during engraving to protect the lens from smoke and dust.

2. Faulty Focusing Mechanism- Mechanical Error

Using a focusing block to set laser focus
Using a focusing block to set laser focus

Another possible reason for reduced laser performance can be due to a faulty focusing mechanism.

Most entry-level diode lasers come with a convenient mechanism to set the right laser focus, such as using a focusing block or a metal probe.

These probes are manufactured to set the exact distance between the workpiece and the laser to set the laser focus.

However, over time, the focusing block can be slightly deformed due to repetitive use, which leads to improper laser focus.

This deviation in the laser focus can sometimes drastically impact the ability of the laser to make a clean cut, like it used to make before.

How do you Keep the Laser Focus in Check?

If you feel that your laser is not cutting like it used to, even after cleaning the focusing lens, then it is likely the issue is with the focusing block that you use to set laser focus for the project.

In that case, you should perform a focus test that helps to find the right focus distance for your laser.

To perform this test, you need to engrave multiple lines with laser set at different focus distances.

Once you complete the test, analyze the results and look for the focus distance that produced the finest line.

If that distance does not match the thickness of the focusing block of your laser, then it is likely that your focusing block has deformed over time, and you need to look for a new focusing block.

3. Exhausted Laser Source- Worst Case Scenario

Replacing the laser module
Replacing the laser module

While the above-mentioned factors are the most common culprits for a weakening laser, it’s also possible that the laser source itself has reached the end of its lifespan.

This is especially true for diode lasers, which have a limited operating time due to the gradual degradation of the diode source.

Similarly, CO2 lasers can also lose their power over time, and you might need to replace the laser tube to get your laser back to its full potential.

Identifying a Worn-Out Laser

Here are some signs that your laser source might be exhausted:

  • Significant power loss: Even after cleaning the lens and adjusting the focus, the laser power seems significantly weaker than it used to be.
  • Uneven cutting/engraving: The laser cuts or engraves unevenly, with varying depths and inconsistencies across the design.
  • Burning instead of vaporizing: Instead of cleanly vaporizing the material, the laser starts burning and charring the edges even after setting the right parameters.
  • Laser beam discoloration: The beam of a diode laser appears duller or discolored compared to its original bright, vibrant state.

Extending Your Laser’s Life

Here are some tips to maximize the lifespan of your laser and minimize the risk of premature exhaustion:

  • Avoid using the laser at maximum power output frequently.
  • Clean the lens and other optics regularly.
  • Use air assist to protect the lens from debris and dust.
  • Follow the proper maintenance and operation practices.
Hey I'm Unni. I am a laser and CNC expert at Mellowpine. You can also find me on Mellowpine Lasers YouTube channel. If you have any questions related to CNCs or Lasers, I'd be happy to answer them. Reach me at mail@mellowpine.com

Leave a Comment