Determining and Testing the Wattage of Your Laser
It is important to test your laser’s performance on a regular basis to ensure the laser is operating as it is intended. Below is a simple method to do so by determining the maximum speed necessary to cut through a 1/8’’ thick piece of acrylic. The benefit of this method is that it doesn’t just measure the power of the laser coming directly out of the tube, but it also takes into account the optics (lenses and mirrors) and the laser’s focus.
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What You’ll Need:
(1) A piece of acrylic. The acrylic must be at least 12” by 7” in order to use the included color-mapped file and should ideally be 1/8” thick, but a 1/4’’ thick piece will also work. In order to keep track of your laser’s performance over time, you should always use the same thickness of acrylic for repeated testing. We recommend that you repeat testing every six months and keep a record of your previous results.
(2) A color-mapped file. We provide a color-mapped file below in a variety of different formats and versions, including CorelDraw and Adobe Illustrator, at this link: Files for Testing Laser Wattage
(1) On the Printing Preferences General tab, enter your “Raster Settings” as indicated below. In this particular example, we are using a 50-watt Epilog Helix. The recommended Raster Settings are 300dpi, 90 speed and 70 power.
(2) On the Printing Preferences General tab, select “Combined” so that the job can both Raster and Vector cut, and use Center-Center Engraving. The Vector Settings on this tab will not be used since we will be utilizing the color-mapping function, so those settings can be set at any value.
(3) On the Printing Preferences Color Mapping tab, enable the color-mapping function, and enter the power and speed as shown below.
NOTE: For lasers that operate below or above 50-Watts, the speed range should be adjusted accordingly. For example, if this method is used with a 30-Watt Epilog laser, the starting speed should be no faster than 9, whereas if the method is used with a 75-watt laser, the starting speed should be no slower than 20. Choose successive speed increments that make sense for your specific laser and wattage.
RGB values and corresponding power and speed settings for the included laser file are shown below. If you modify the speed settings for a different wattage laser, the text in the laser file should be edited to correspond with the color-mapped settings you used. All text in the file provided is editable.
(4) Place the acrylic in your laser, and send the project to the laser. If everything is set up correctly, your laser will raster all the black text and attempt to vector cut all the colored text using different speeds based on the color-mapping settings.
(5) Evaluate the marks. Once the job has been completed, remove the piece of acrylic and evaluate which of the stars fall or can be pushed out of the acrylic. With this particular 50-Watt laser, stars cut at speeds 15, 17, and 19 are removable, but the laser does not cut through any of the stars at higher speeds, and the stars at higher speeds were therefore not removable.
According to the recommended settings from the manufacturer, a 50-Watt laser should be able to cut through 1/8’’ thick piece of acrylic at 100 power and 15 speed. This laser was successful at those settings and is therefore operating better than expected.
What if Your Laser Can Only Vector Cut at a Speed Lower Than Recommended?
For example, if you have a 50-watt laser, and you have to run it at 12 speed to cut through the acrylic, you should try to determine the cause of the problem.
First, we recommend that you clean all of your optics. Follow your manufacturer’s recommended instructions, and use only the recommended cleaning products. Be careful not to scratch any of the lenses or mirrors during the cleaning process.
When you are finished with cleaning, repeat the speed-cutting test on a new piece of acrylic, and evaluate your results. If the results are the same, you should next evaluate the laser’s focus.
If you are using the auto-focus, compare the focus height set by the auto-focus with the manual-focus gauge provided by the manufacturer. If there is a difference, you should experiment running the test again with the laser focused at different points. You may need to go closer to the acrylic or further from the acrylic to bring the laser to its optimal focus point if the auto-focus and/or gauge are not calibrated correctly.
Other potential issues you should consider are:
- Scratched or damaged optics. Check your lens for scratches, and if scratches are visible, contact your manufacturer for replacements.
- Scratched or defective mirrors. If any of your mirrors are not highly reflective or have visible flaws, contact your manufacturer for replacements.
- A defective or old laser tube. Laser tubes lose power over time. A brand-new laser tube is expected to perform better than a 5-year-old laser tube. The life span of laser tubes varies substantially by manufacturer. Based on message-board reports, tubes from American manufacturers tend to be of a higher quality and have longer lifespans than tubes from non-American manufacturers. Depending on the manufacturer, tubes can last as little as 2 years or as long as 10 years. The good news is that most tubes can be recharged, which is a much more cost-effective solution than buying an entirely new laser or laser tube. Contact your manufacturer for more details.