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Brian Knuckles
01-07-2010, 12:18 PM
Hello everyone. I have some glass that I am trying to burn the backing off, however most of the time I break the tile.

I run my epilog 120watt at 20s/100p/200dpi

When I speed up or lower the power it leaves residue behind. Anyway to keep the glass cool while its lasering?

thx

Dan Hintz
01-07-2010, 12:56 PM
I've similar issues with pre-made tiles, so I switched to painting my own glass. I thought about having the tile sit in a plate of water, but never got around to trying it. My concern was if the water did not keep the glass cool (never ran the calculations to see what kind of heat transfer I could expect), it would shatter and spray water up onto the optics... and then it would be a real mess :(

joseph zalewski
01-07-2010, 9:05 PM
Did you try laying it on a damp paper towel ?

Dave Johnson29
01-08-2010, 10:09 AM
I run my epilog 120watt at 20s/100p/200dpi


Why not try some faster runs but do 2 or 3 passes? Find a speed that does not crack the glass then repeat. At 120W that is a lot of heat to be pumping into the glass at that slow speed.

Do you have an exhaust or air assist system? One or both would also help dissipate heat.

Darryl Jacobs
01-08-2010, 1:47 PM
I have been lasering glass plate for a while to make inking plates for a friend of mine. (about 6" to 12" square and 1/8" thick glass) One of the issues with glass is the temperature differential between the top and bottom (also depends on the quality of glass and thickness).

What I mean is that if you keep the bottom of the glass too cold and the top only gets hot in a very localized area of the lasering, you will crack the glass. This is mainly true when you have to laser a lot of surface area on a smaller piece of glass. I usually laser with the exhaust fan on only. I have a lot of suction going so there is good airflow across the glass with the air assist off.

I have burnt paint off of glass successfully, but have done it in several passes and cleaning between the passes to get rid of the charring which just slows down the burning process of the next pass. I hate doing it as there is a lot of fiddling and practice pieces involved.

Don't know if there is anything usefull above, just rambling on how much I hate taking paint off glass!!

Darryl

Brian Knuckles
01-21-2010, 2:31 PM
Hey thank you everyone for your help...

I tried everything, evening cooling then in 20 degree temperature...
The best thing seemed to just run at a faster speed and just burning it twice.

Again...thank you

Doug Griffith
01-21-2010, 2:41 PM
What I mean is that if you keep the bottom of the glass too cold and the top only gets hot in a very localized area of the lasering, you will crack the glass.

If it's a heat differential issue, have you tried heating the glass prior to lasering? Just a thought.

AL Ursich
01-21-2010, 11:26 PM
If it's a heat differential issue, have you tried heating the glass prior to lasering? Just a thought.


Now that is a great idea.... I bet it would work....

And Remember, Glass is a Fluid that is a solid at room tempature.... From my Sony Picture Tube Glass Technology Class.... 1995

AL

Dan Hintz
01-22-2010, 10:48 AM
And Remember, Glass is a Fluid that is a solid at room tempature...
Pretty much everything that's solid at room temperature is a fluid at some higher temperature ;)

I think what you meant to say was glass is a fluid at room temperature, but one that moves at an extremely slow rate. Even though it is still debated some places, it is now (relatively) commonly agreed in scientific circles that glass is a solid at room temperature.

The wive's tale of glass being a slow-moving liquid at room temp came from people seeing old old old glass as being thicker at the bottom. This was actually done on purpose by glass artisans as it gave a sense of depth to their stained glass windows. Proof against the liquid theory can be seen in the fact that occasionally the thick part of the glass was found to be at the top, done either on purpose for some unknown effect or (more likely) by an unskilled apprentice.

Bill Cunningham
01-26-2010, 8:22 PM
These wouldn't happen to be the glass 'tiles' from HD would they? I seen some of these in the store and thought 'hey' these might be cool to engrave.. Nope!!! what ever they use for the coloured backing ain't going nowhere with my laser.. I did engrave them, but used a double transfer paper mask, lasered it, then finished it with the sand blaster..