Loss of Power after aligning and cleaning mirrors

[simonsoot]

This is a second hand Chinese CO2 laser 80-90W, 20x28" bed.

Here is the backstory:

I've owned laser for two years, after a year the laser was not acting the same, and I thought the mirrors had come out of alignment. Fool that I was, it was just dirty optics. Doh! I did manage to align the mirrors, but in the end I made it worse.

So that happened one year ago and I recently noticed my engraving lines "walking", again I assume to poor alignment. This happened to be the farthest distance for the laser to travel (lower right of the bed), during movement if the laser was out of alignment I assume it would cause this.

So last weekend I though I would give aligning the mirrors another shot.

After aligning the mirrors for a second time, it seems the laser is cutting straighter than before, and is more aligned than before all over the table (based on the laser hitting the same spot on a piece of tape covering each mirror.

and here comes the but...I have lost power. I could cut through 3mm baltic birch with setting of 10 mm/s and 21% power. Now I must go to 70% power and 8mm/s.

Since then I read a post where the chiller had antifreeze in it, so I cleaned out my water reservoir, ran clean water and vinegar through the lines for 2-3 hours, rinsed the lines, and put in new distilled water.

Since there is no time machine to go back and undo my personal mirror alignments, what else can there be? Or, more importantly, is there a field technician in the Portland, Oregon area that anyone can recommend? If someone wanted to do this on the side for me, obviously I am only making it worse!

If the laser is not hitting the center of the focal lens, do you lose power? Or, am I hitting the first mirror in such a way to lose power?

I am probably missing some info...

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[Dean448]

The goal is the hit the mirror center but you shouldn’t loose power if it’s off center a bit.
I would check focal length. Take a series of test cuts at various heights to find the optimal height.


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[fixtureman1]

Is your nose cone heating up beam maybe bouncing off the side of it

[simonsoot]

Thanks Dean, I checked but will double check.

[simonsoot]

Is your nose cone heating up beam maybe bouncing off the side of it

This is something to look into for sure. I will take a look tonight and let you know.

[simonsoot]

fixtureman1, you were spot on, THANK YOU!!!! I was over complicating the solution, but the third mirror was not pointing close enough to center that it was hitting the side of the nose cone upon exit. 1/8 of a turn on each thumb screw and miraculously i had the same, if not better power than before. Turned another 1/8 turn to ensure it was completely off the side.