Our CO2 laser cutter (60w Chinese red and black) works with reasonable power when we start it up and begin working, but after just 15-20 minutes, it loses significant power. When we start, it will cut 3mm acrylic at 15 mm/s (60-80% power), but this quickly drops to below 5 mm/s (80% power). We have replaced the tube without it solving the problem. There are new mirrors and a new lens in the machine. We can see that the water temperature stays below 20 degrees. We suspect it’s the power supply, but what do you think?
Have you also changed the power supply for the tube?
sorry, too fast reading, yes it could very well be your power supply
I have a similiar occurance with my 130w …
I found that it is the temperature of the tube….or so it seems…
When I come in to work usually early mornings… The temperature has been in the 50’s here in Florida and I find when I start cutting the Current is (lets say) 12ma on the inline meter…
after cutting for 10-15 minutes, the current will drop down about 1.5ma …
the tube
I have a built-in chiller and while it does settle out and become stable…there is this small drop in power…I believe my temperature is set to 25C max so this means that the tube is probably starting around 18C and stabilizing at the chiller max setpoint..
if you have a water bucket system, you can try cooling the water down a bit with some ice…
just to see if the power comes back up a bit…
But there are many folks on here that I am sure have some good advice…
I have wondered what a good temperature is for the CO2 tubes to run at..!
And if running the tube cooler is a problem with ‘shock’ say maybe around 20C…
Anyway I will investigate this a bit more…
chuck
EDIT: found on AI Search
For a CO2 laser tube, the ideal operating temperature for the cooling water is generally 15°C to 25°C (59°F to 77°F), with many users aiming for around 20°C (68°F) for optimal performance and longevity, as higher temperatures decrease power output and can damage the tube over time. It’s crucial to maintain this range with a reliable chiller and protect against freezing in cold conditions, as cracked tubes are a major risk.
Key Temperature Guidelines
- Optimal Range: 15°C - 25°C (59°F - 77°F).
- Ideal Target: Around 20°C (68°F).
- Upper Limit: Staying below 24°C (75°F) is recommended to preserve tube life.
- Lower Limit (Freeze Risk): Avoid freezing temperatures (below 0°C/32°F) which can crack the glass tube.
15 degrees C is probably just the lower limit, it depends on the ambient temperature. Condensation can be a problem.
At first, with my K40 I used a bucket and ice cubes. The temperature fluctuations are not good, from ice water to …25…30 degrees C. I quickly bought a real cooling machine. My temperature range is between 18 and 20 degrees C.
Went into the office this morning and set my temp to 20C
was set to 25c From the vendor, now running 18-20C 
so I guess I copied you
seems to,be running smoothly…
No, my friend, now you’re just using the same temperature set as the rest of us. 
However, I have only had good experiences with this temperature for almost 6 years, no condensation and the cooling compressor does not start too often during normal old boy driving.
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Then I am in great company !
had this laser for a year now and finally getting around to the items I should have looked at when I un- packed it
I do only us it at less than 35w most of the time , some thick acrylics 50w, but on a 130w tube it generally runs under 16ma…
…then you will have this laser for many years. That is more than double my 60 Watt. It is incredible that you can create such fine details with such a powerful machine as you often prove.
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I cut everything with a 3" lens adjusted at 11mm off the material, with 15psi air…
fantastic wood cuts
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