Stuff you SHOULD NEVER try to laser

[Mitchell Andrus]

I guessing any beam bouced back towards the lens would be as unfocussed as the beam that came through it the first time, so I think i'd be OK.

But....

You try it first and ley us know what happens.

Mitch

[Bruce Volden]

Wive's tales??? I've engraved many a mirror, both sides! Still have the original lens-11+ years old now. I have replaced a couple of bounce mirrors when the coating flaked off for whatever reason. I'm thinking that when the focused beam strikes the reflective surface of a mirror being engraved, the energy of the beam has already done it's "work" in ablating the surface thereby nullifying any reflection??? Doesn't that sound smart.
That 6 years of high school is really paying off.



Bruce

[Rodne Gold]

The mirrors in your laser are polished steel that is gold plated , if you do try laser something polished that wont absorb the beam , it will scatter it with potential harmful effects if you dont run a closed box. The beam will diverge a lot and pobably wont be that coherent by the time its bounced off so it's most likely not that big a deal inside the box.
We too have lasered many mirrors both sides and never had a problem , as Bruce says , the laser energy is absorbed by the time it has done its work on the glass.
You dont laser stuff like teflon either..be careful of plastics and some synthetic fabrics/foams , some will not respond well and some are toxic.
Of course flamable items are your biggest risk in a laser , far more damage caused by laser fires than most anything else.
We have tried just about anything we can get our hands on in the laser , in terms of plastics , if it smells funny , like acrid and/or discolours , we just pass.

[Joe Pelonio]

Stop by the shop here and I'll show you the etching on the inside of my glass top where the beam bounced off the front of acylic mirror. The idea that the laser "does it's work on the mirror" is only true for me if I apply transfer tape to it. You won't get me to put bare mirror face up in there again. A couple of marks on the glass I can live with, but that beam could just as easily cut through a wire, hose, or belt.

[Dave Jones]

I'll show you the etching on the inside of my glass top....

I'm guessing you meant "acrylic top". UV laser engravers use acrylic lids because glass would pass the UV through.

[Rodne Gold]

I wonder why you are having those issue Joe?
I do a lot of acrylic mirror work front and back engraved , same with glass and in fact the "vinyls" we use as masking for etching and sandblasting are polyester foils (silver and gold) and are highly reflective and we never have a bounce back or internal etching problem?

[Tom Radachi]

Could you put laser beams on a sharks head?

No, only on evil sea bass...

[Joe Pelonio]

I'm guessing you meant "acrylic top". UV laser engravers use acrylic lids because glass would pass the UV through.

No, Dave, my Epilog has a glass top. Rodne, I have cut through mirror gold and silver poly films on things with no trouble, but always put transfer tape on it.

[Joe Pelonio]

I went ahead and contacted Epilog technical support. They say mirror must be done upside down, or there's a "chance" that it will reflect back and damage the machine. I'd be curious if owners of other makes find that same recommendation from their manufacturers.

[Dave Jones]

This wasn't about mirrors, but about reflections. I saw a post somewhere by somebody using an industrial sized CO2 laser (hundreds of watts) that was cutting metal and said aluminum caused more problems than other metals when cutting since the beam would reflect back up and refocus through the lens, go along the optic path, and go back into the laser source and damage it. I think it was because the molten aluminum was very reflective. He mentioned some special device to reduce the reflection back down the optic path.

[Michael Wells]

I have to weigh in here and side with Joe... I have a 100W Explorer with a nice little black scar on the inside of the acrylic top from a mirror that I surface engraved, back when I was experimenting with my machine.

[jeremy levine]

This wasn't about mirrors, but about reflections. I saw a post somewhere by somebody using an industrial sized CO2 laser (hundreds of watts) that was cutting metal and said aluminum caused more problems than other metals when cutting since the beam would reflect back up and refocus through the lens, go along the optic path, and go back into the laser source and damage it. I think it was because the molten aluminum was very reflective. He mentioned some special device to reduce the reflection back down the optic path.

Could you mean this
http://www.nilno.com/laser_intro/optics.html
Search the page for "polarizer"

[Joe Pelonio]

I have a new material that you CAN use. I never tried it before today. I needed to make a mounting pattern for a cut acrylic logo to go on a wall and was all out of polytag which I normally use. I looked around and found a roll of Tyvek that I keep for doing cheap short term banners. It's made of pressed very fine, high-density polyethylene so is like heavy paper but
waterproof and tear resistant. It's like they make house wrap, shipping envelopes and painters throw-away coveralls with, but what I get is stiffer and pure white. Anyway it cuts beautifully. Unless you have a vacuum table he pieces like to fly out the exhaust. I used a temporary artist's spray adhesive to stick it onto a sacraficial piece of MDF so it would lay flat and not escape.

[Barbara Buhse]

Joe,
How about a picture of that cut tyvek?

[Joe Pelonio]

Maybe I'll do another sample of it tomorrow. It's going out for installation
in a few minutes and my camera is in my Explorer, which my wife borrowed to take her mother to the eye doctor (87 and can't get in my wife's Liberty, plus not enough room in it for the wheelchair)