New laser tube. Worked perfectly first time. power dropped significantly 1 week later

[Joe Jordans]

Hi Everyone.
I have a 'China Blue' laser cutter/engraver. I recently replaced the tube that came with the machine with a new one from CloudRay. (45W tube https://www.cloudraylaser.com/collectio ... 6778244236) The sales team have been very good so far. I got an out of office reply when I tried to contact them today...)
I have an ammeter and have limited the current to 20mA
I also bought a radiator type chiller to make sure that the tube docent over heat. The chiller shows the temperature and and has an alarm for water flow and over temp.I also upgraded the mirrors to Si Mirrors.
My machine is in an uninsulated shed, It is winter here in Australia and it has been very cold. night time temperatures have been around 6C and I have operated the laser at about 10C.

The first weekend, my laser worked perfectly and I was presently surprised by the amount of power I had as my first laser was advertised as 50W. This weekend when I was testing on some 3mm MDF, I could only get a very faint line at 100% power 15mm/s. normally, I could cut with ~50% power. The mark made by the laser was very fine, ie. the laser is focused to a very fine point.

I tried to clean the mirrors and did not get any improvement.

has anyone had a similar problem? I thought about getting one of these https://www.bell-laser.com/product-page ... -200-watts power probes for $135USD to try to track down the problem. is there another (free or very cheap) way to test the laser power?

[Dave Vigness]

Touch base with Russ. His Dohicky goes for £29 and takes any K type thermistor. You can pick up a meter just about anywhere. I got mine off Amazon for $18 USD. https://www.amazon.com/gp/product/B00FF ... UTF8&psc=1

[Joe Jordans]

Thanks. How do I get in touch with Russ?

[Joe Jordans]

Don’t worry, I found his email address

[Dave Vigness]

Sorry I didn't get back right away, honey do projects.

I like the meter he uses in his videos, it has a max button so you can see what you had. The reading will drop immediately on beam off so it's a handy feature. My multi meter actually has a temp probe input, but it has a HOLD instead of a MAX. Not quite the same thing.

Check out his video on using it.

[Joe Jordans]

Thanks. I ended up emailing Russ. He suggested some troubleshooting steps. I’m pretty sure my laser is fine.
I think my problem is with the head. It is a bit flimsy and I think I knocked it out of alignment. I think that the laser spot is hitting the side of the tube. I’m still having trouble getting it aligned but at least I know where the problem is.

[Joe Jordans]

All working now. It was an alignment problem at the last mirror.
Diagnosed by burning acrylic after each mirror and removing the lens and testing on the table. There was power all of the way but nothing when the lens was replaced.
The beam was hitting the side of the tube and missing the nozzle. The last mirror is a bit low but I don’t have any vertical adjustment so I had to align it with the centre by adjusting the last mirror. The beam is now slightly off vertical.
I need to upgrade the head to get some vert adjustment

[Gene Uselman]

Russ and I collaborated on a tool to check how the beam is aligned with the nozzle-

.

anal thermometer2.jpg

The four corners of the bed should be checked for best alignment- the holes should just go outside of your nozzle.