New to laser Etching, how come laser is loosing power

[Rich Ebner]

I'm new to this and after making etched wine and beer glasses for my wife and friends I've got so many requests from friends and projects at work that I decided to get a laser. So, after looking and seeing how the response would be I decided on getting a low budget (2800.00 form Amazon) 40w laser. Currently, it takes me about 12-15 min to etch a glass by sandblasting. I was hoping that I could cut that cycle time to about 3 min with the laser. Anyway, I got the laser and after looking on this site and others trying to get tips on how to get the finish looking acceptable I decided that I'm kind of stumped. I've got about 3 min of power on time on the laser (in 24 sec increments). Yesterday I turned on teh laser and was going to try the wet paper technique but the laser would't even make any marks on the wine bottle I was using. I tried it on a bare bottle and no marks at all. I checked the alignment and I adjusted to get in the center of all the mirrors except the head, which I haven't figured out how to check. I tried a test name on a square of 1/4" plywood and the lettering is lighter than expected. What could be the problem? Is it possible that the laser tube is going bad or maybe the power supply is out of adjustment. The manual is sooo bad that it concentrates on software and nothing about the machine.
Any help would be great.

I got this last week so I can do an event which is the second one for me and it's a big one which I'm hoping to kick off my business with. I'll be pretty handicapped if I have to rely just the sand etching since there is going to be a bunch of people at this event.

[Bert Kemp]

I would check and make sure the cone on the laser head is tight and not getting in the way of the beam coming out.

[Dave Sheldrake]

Sounds like heat, make sure your water connection is the correct way round and you don't have any air bubbles in the tube.

cheers

Dave

[Rich Ebner]

I've checked the water and that's correct. How do you check the focal length of the head. The laser came with a plastic gauge that's about .1 X .4 inches (2.8 X 10mm) and I assume that the thin end is the focal space gauge. But, nowhere in the manual is there a reference to head height or the head.
During the first phase of trouble shooting I did remove the head lens and found some debris so I cleaned and re installed it. It didn't make a difference in the output though.

[Dave Sheldrake]

Just read it again a bit more carefully ....yup I'm with Bert, the final cone alignment or focal distance is the problem.

What model of laser is it? the focal point is measured from difference places on different machines (even though the lens's may be the same focal length)

cheers

Dave

[Clark Pace]

Ditto on checking power in different places. Do a cut or etch in the upper left and corner. Usually but not always the best alignment. See if it cuts and etche well there. Do 1 1/2 cut or etch.

[Rich Ebner]

I'll redo the alignment and check. The laser is Shen Huil. Amazon has it listed as a generic 40W desktop laser engraver but it's about the size of a large office network copy machine.

[Rich Ebner]

The alignment works! Thanks for the help. I also guessed the the focus spacer is to be on the long end 10mm or .4" Now to continue looking up past posts on how to get a better finish on the glass by messing with the DPI / MM speed and wet paper/ dish washing soap stuff. I've got a HUGE learning curve to get through in a short time.