Dang it!!

[Barry Clark]

I wasn't paying attention today while working on a design on glass...:(
I know better than to do what I did but for some reason my mind just wasn't in the game...
http://i656.photobucket.com/albums/uu282/Barry50_2009/lens002.jpg

http://i656.photobucket.com/albums/uu282/Barry50_2009/lens001.jpg

Don't try and vector glass using high power and low speed. :o
Actually the vector wasn't intend, I was using the lines as guides and forgot to turn off that function..

$230.00 out the window..

[Frank Corker]

What has happened? Can't make out from the photos (too blurred) I assume you've cracked a lens.

[Barry Clark]

Yep.. It has several cracks and a burn into the glass on either side.
Sorry about the pics, I should upgrade to a better camera.

[Frank Corker]

Maybe the same thing happened to the lens on your camera! What are the chances of that? Who would ever have thought coincidences could be so amazing.

[Barry Clark]

Good One:D
Actually that camera fell off my motorcycle while I was doing a short clip on a tree lined road several years back:o It's held together with superglue and duct tape.. Really

[Barry Clark]

Back on topic here:cool: Has anyone bought a lens off of the dealers on ebay? I found several lens that most likely will work in the $65.00 $70.00 range.

[Dean Fowell]

Hey Should be good try a company called II-VI rhis is all they do and build might get a dealI have always brought lenses off them for bigger machines

:cool:

[Curt Stallings]

I don't see why vectoring glass would do that. Are you sure that the lens wasn't dirty?

Curt

[Barry Clark]

Oh yeah It was the vector.. I was in the room and occupied and just happened to look over about 30 seconds into that point when the head started smoking and the beam futzed out. Maybe two hours since the last cleaning..

60 watts at full power and 2.5 speed over a masked image isn't a good thing..

[Kim Vellore]

I am curious, Why would your lens burn up if you vector glass? Is glass reflective still why would it burn your lens? Kim

[Garrett Nors]

Yeah, I don't understand either :confused:

[Barry Clark]

I don't think I'm being "baited" here...;)

Think about it.. If the beam is fully reflected back into the lens the full power in now applied to said lens.. It's going to act upon the lens in the same way it does the glass only reflected off the mirror to burn the opposing side of the lens also..
The cabinet enclosing the laser is there to protect the user from stray "beams" that could cause damage..
Unless one of the "wizards" here can prove otherwise, I'm pretty confident this is exactly what happened..

[Garrett Nors]

But regular mirrors shouldn't be able to reflect the beam like that, should it? I've been burning through mirrors for years (both sides) and nothing like this has happened. What a weird mishap.

[Barry Clark]

But regular mirrors shouldn't be able to reflect the beam like that, should it? I've been burning through mirrors for years (both sides) and nothing like this has happened. What a weird mishap.
Garrett,
Normally I don't have any issues either, but the power was 100% and speed was 2.5 on the machine. The vector area wasn't intended on this project but I didn't have that function turned off.

I've done dozens of mirror and glass projects and never had an issue prior to this:eek:

Lesson learned: Make sure to check your settings and artwork before running a job;)

[Curt Stallings]

Seems to me that when the beam hits the glass it immediately micro fractures it and makes it impossible to reflect back. Just seems weird.

[John Noell]

Back on topic here:cool: Has anyone bought a lens off of the dealers on ebay?
No, but I was happy with the lens I got from Laser Research Optics (http://www.laserresearch.net/).

[Doug Griffith]

I don't think I'm being "baited" here...;)

Think about it.. If the beam is fully reflected back into the lens the full power in now applied to said lens.. It's going to act upon the lens in the same way it does the glass only reflected off the mirror to burn the opposing side of the lens also..
The cabinet enclosing the laser is there to protect the user from stray "beams" that could cause damage..
Unless one of the "wizards" here can prove otherwise, I'm pretty confident this is exactly what happened..

Not a wizard but... besides the loss of energy absorbed in the glass being lasered and the mirror surface itself not reflecting the full C02 wavelength, the beam itself is focused on the surface by the lens. It converges the beam to a focal point that would then reflect back at that same convergence angle (and I'm sure very scattered). The energy will never be "fully" reflected back to the lens in focus. That's my take on it. See my exaggerated illustration.

Whoops, just realized my theory doesn't apply here. I was thinking it was a masked mirror being lasered.

[Doug Griffith]

Not a wizard but... besides the loss of energy absorbed in the glass being lasered and the mirror surface itself not reflecting the full C02 wavelength, the beam itself is focused on the surface by the lens. It converges the beam to a focal point that would then reflect back at that same convergence angle (and I'm sure very scattered). The energy will never be "fully" reflected back to the lens in focus. That's my take on it. See my exaggerated illustration.

On that same note, could it be that you were out of focus and enough energy was directed back to cause the damage?

Double Whoops!

[Dan Hintz]

This doesn't make sense... glass (molten or solid) does not reflect any appreciable portion of the beam. Is it possible you had some build-up from processing something other material (like wood or plastic) and it finally caught up with you?



Curt, the laser melts the glass... the fracturing occurs when it resolidifies via a stress point (I went into more detail in an earlier thread).

[Barry Clark]

* waving white flag * I give up..

Simply put, The lens got fried... Many glass projects prior to this. Improper Vector speed/power settings were the cause..:( Unintentional though they were.

Nothing I've read to this point proves it otherwise.

[Dan Hintz]

Nothing I've read to this point proves it otherwise.
I swear I'm not trying to be rude when I say "Nothing I've read to this point proves that was the cause, either."

If I were you, I would make sure you are certain of the reason for this happening, else it could happen again. What you're suggesting is a piece of glass (that does not reflect or pass energy at that wavelength) somehow reflected and focused that energy back onto a lens (transparent to 99.9% of that energy) with enough power to fry it. Unless the lens was contaminated...

[Barry Clark]

Do you think the tape over the glass may have caused this Dan? I'm quite confused as the lens didn't have but maybe two hours since it was last cleaned..

Possibly the tape burned and clouded the lens? As I didn't actually witness what happened only the aftereffects, I'm rather clueless at this point:confused:

[Mike Null]

I'm in agreement with Dan. What did you clean the lens with? I'm suspecting moisture may have caused the problem.

[Rodne Gold]

You could have had a misalignment and the frame that holds the lens overheated due to the beam hitting it - you said you saw the head smoke - the lens itself wont smoke..has to be something else like a deposit on the lens or the hot frame caused the lens to fracture.
Lasering glass will never reflect the beam back , glass is impervious to the laser - it heats up impurities in the glass and temp differences and cooling causes fracturing.

[Scott Shepherd]

Barry, it's quite possible it was the tape. Burning glue like that could have been the issue, in my opinion.

[Mike Gaston]

I've used my laser to score lines on glass often and never had a bit of trouble. Its how I break all the glass I cut. It had to be a heat build up at the lens for some reason.

[Barry Clark]

Thanks for all the reply's folks.
I'm pretty sure it was a buildup of residue from the burnt tape. If I had been hovering over the job I'm sure I may have caught it before any damage.

Found and purchased a lens from Laser Research Optics.. (http://www.laserresearch.net/)

Thanks John.

[Dan Hintz]

I agree with the tape being the likely cause... even a light burn on painter's tape can produce a surprising amount of particulate matter.