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Laser Moves but Does Not Fire: 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 moves but does not fire

Is your machine just tracing the cutting or engraving path without firing the laser?

This is a laser issue that often triggers panic in laser users, thinking that there’s something wrong with their laser module.

But don’t fret! It does not necessarily have to be as serious as it sounds.

I’m Unni, and I’m a laser engraving expert. In this guide, I will explain the possible reasons why your laser moves without firing and how you can fix it.

Faulty Focusing MechanismImproper mirror alignment or faulty laser focusing lensCheck mirror alignment and clean the focusing lens regularly
Broken Laser ConnectionFaulty connector or broken cableReplace faulty connector or broken cable
Incorrect Firmware SettingImproper $30, $31, and $32 settingsInput the right settings or reset to factory default
Worn-out Laser SourceImproper maintenance or exhausted laser lifespanReplace the laser source
Possible reasons your laser is not firing and their fix

1. Faulty Beam Delivery System

Beam delivery mirrors in a CO2 laser
Beam delivery mirrors in a CO2 laser

One of the most common reasons for this issue can be a faulty beam delivery system or the focusing mechanism.

If you are a CO2 laser user, make sure the focusing mirrors are aligned properly.

This is because even a slight imperfection in the mirror alignment can alter the course of the beam, preventing it from reaching the workpiece.

Similarly, for diode lasers, check if there is something blocking the focusing lens, such as dust or some other foreign object lodged into the nozzle.

In some rare cases, the housing of the lens or the lens itself is damaged, which blocks the laser from reaching the workpiece.

This type of issue can be detected by touching the laser nozzle after a few seconds of operation. If the nozzle housing feels warm to the touch, it means the laser is striking against the nozzle and increasing its temperature.

2. Broken Laser Connection

Checking the Laser Connector
Checking the Laser Connector

Another possible reason for your laser not firing can be a loose or broken laser connection.

In this case, the controller sends the command to execute the process, which is interpreted by the stepper motors to trace the design, but the laser does not fire due to its faulty connection.

Generally, the laser connection is present on the top of the diode laser module.

Therefore, it is important to routinely check the laser connection and ensure there is no damage to the cable.

If the cable is loose, you can tighten it and get back to your laser projects. Whereas, if the connector of the laser is damaged, you can purchase a similar connector and repair the connection.

However, if the cable is damaged, it is preferable to replace the entire cable to avoid accidental disconnections during future projects.

3. Improper Firmware Setting

Checking the machine settings in GRBL console
Checking the machine settings in the GRBL console

Now, if everything looks good in the hardware and your laser still fails to fire, then it is likely that you have messed up your firmware settings.

While improper firmware settings can be fixed, it requires patience and a good understanding of the machine setting of the laser.

To check this, first connect your laser to your computer.

Then, navigate to the G-code console and enter $$ to get all the values for the machine settings.

Under this, specifically look for $30, $31, and $32 settings.

Ensure that $32 = 1, as it activates the laser mode and allows the laser to turn on and off during the project.

Similarly, check the value corresponding to $30. Generally, it should be set to $30 = 1000 and $31 = 0.

The $30 and $31 correspond to the maximum and minimum power output of the laser, and it is important that the $30 value is equal to the S-value max of your laser software.

To check the S-value in Lightburn, you can navigate to Edit > Device settings and check the S-value Max in the lower right section of the menu.

If the settings do not match, you can navigate to the console, input $30 = 1000, and press enter. The console will register the new value.

Alternatively, if there are multiple settings that need to be adjusted, you can enter $RST=*, and this will reset all the settings to the factory default values.

4. Worn-out Laser Source- Worst Case Scenario

Replacing the laser module
Replacing the laser module

If you perform all the above checks and your laser still does not fire, then it is likely that you have exhausted your laser source.

Generally, a laser source exhausts gradually. So, if you had noticed that your laser is not cutting like it used to, before completely turning off, then it is likely the laser source is exhausted.

Another way to test a diode laser is to perform the 5V laser test.

Most diode laser manufacturers, such as Sculpfun, provide a 5V output in the control board of the laser.

To test the laser module, you can disconnect the laser from its original connector and plug it into the 5V output connector present on the board.

If the laser fires when connected to the 5V output, it is likely that there is some issue with your software compatibility, and your laser source is working fine.

Note: Use proper safety when performing a 5V test because the laser will fire at 100% power. Therefore, it is important to wear your safety glasses and place a non-flammable material like sheet metal under the laser to avoid burning the material.

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