lasering tin foil, damage potential?

[David Fairfield]

Guys, I'm trying to think up a way to block the laser from cutting past a specific depth in a "parts sandwhich" Its a bit complicated to explain why I need a pre-assembled sandwhich.

Anyway, I'm considering inserting a layer of kitchen foil underneath a layer of cardboard to stop the beam from penetrating past that depth.

So my question is, does anyone forsee any potential to damage the machine by lasering tinfoil, and if so, what can be done to prevent it? I'll be using 35w and vectoring at about 30% power

thanks!!
Dave

[Doug Griffith]

I use tin foil quite often. You may want to put the shiny side down.

[Frank Corker]

Not long after I got my laser I was engraving something and it caught a piece of tin foil, that bounced up and seared the perspex cover on the laser. Never tried it again after that.

[Doug Griffith]

I think if the foil is beneath the layer of material being cut and can only bounce within the thickness of the kerf (.030?) there shouldn't be a problem. I wouldn't recommend using it to mask areas when engraving though. Again, keep the shiny side down.

[Brian Robison]

David, is it a flat area? If so, use a piece of aluminum or brass or what ever you have around.

[Robert Ray]

I have tried all kinds of ways to cut aluminum foil and copper PC traces with my 35 watt over the past 5 years, all without reflection incidents. You will probably be ok in using it.

The aluminum spreads out the heat very fast, and only if you stay in the same spot with the beam on too long would it melt the metal, becoming a front surface aluminum mirror. At that point it would retroreflect back through your lens, and the lens beam will be expanded.

By the way, I did find a way to cut the foil, but it is not clean. I layed a piece of 1/16" CPVC over the foil, set my power to 100%, speed to 4%, and as the laser cut through the PVC, it releases Chlorine gas, which plasma cut through the foil no problem. And the foil did not stick to the PVC, which cut very straight, but with lots of orange powder all over and a stink to high heaven! This will void the warranty of any laser and can corrode your machine, but I needed to find a way to cut thick aluminum foil for a project of mine.

As far as the PC board material? Well it won't cut because the FR fiberglass material swells up into carbon black under the copper foil. You can raster PC boards just fine for etching thouhg, just spraypaint, then raster away the paint leaving shiney copper ready for FeCl etchant!:D

-Robert Ray

[David Fairfield]

OK cool, I'll use it carefully! Thanks for all the input.

So Doug, what do you use tin foil for?

Dave

[Doug Griffith]

OK cool, I'll use it carefully! Thanks for all the input.

So Doug, what do you use tin foil for?

Dave

I cut quite a bit of fabric that I sandwich between clear acrylic fixtures that have "grooves" for the laser paths. I use foil a few layers down to keep from cutting my fixtures apart. This allows me to build my fixtures entirely on the laser and be more or less "laser proof" when finished.