Focusing Laser

[Ernie Woodburn]

Hi all. New to cnc laser, new to forum. Forgive this question but I have a diode 15 watt universal engraver (manual z axis) and I can't seem to etch glass. My question is do I HAVE to adjust the focus or can I just adjust the z axis until I reach the smallest beam?

[Matt Schrum]

I'm not sure if my Google-fu is at 100% this morning, but I don't think you can etch glass with that sort of laser. Adding a coating to the glass may make it slightly less impossible.

Also, here's a (brief) thread with similar thoughts:
https://sawmillcreek.org/showthread.php?243501-Diode-Lasers

[Ernie Woodburn]

Ok thanks. What about my question on focusing it?

[Chris DeGerolamo]

Ok thanks. What about my question on focusing it?

Focal plane plays a large role in lasering; such is an understatement. So yes, you most certainly want to be in focus. *thumbs up*

[Kev Williams]

Any method of closing or opening the gap between the lens and work is an act of focusing; IN focus is the goal, HOW you focus is moot :)

[Ernie Woodburn]

Any method of closing or opening the gap between the lens and work is an act of focusing; IN focus is the goal, HOW you focus is moot :)


Ok thanks Kev. So I've got better results now on glass. I had my laser about an inch or so high. Now I've raised it up 3 inches and played with the focus. How do you know when it's in focus though. Trial and error?

[Kev Williams]

you do a 'ramp test'-- since you now know your 'close' focus, to do a ramp test you find a length of engraveable material, 4" if you have room, place it in the laser and raise one end about 1/4" with some sort of shim. Focus so the middle of the ramp is your 'close' focus. Now raster engrave the length of the ramp at just enough power to mark the material. You should find the middle engraves while the power falls off at the edges of the engraving. The center of the good engraving is your prime focus distance-

[Ernie Woodburn]

Any method of closing or opening the gap between the lens and work is an act of focusing; IN focus is the goal, HOW you focus is moot :)


PERFECT. Thanks Kev