Strange lasering issues

[Mark Ross]

Take a look at the pics. Parts came back from a customer. Part is a 1/2 inch thick acrylic mirror, 23.5 inches in diameter. There are these weird little "tick" marks along the edge. The one picture I put it under my microscope and it looks like the acrylic is possibly super heating and blowing out?

Checked the master artwork file, it is locked down, read only, and I opened it up. The circle is one continuous circle. To me, it almost looks like the laser is pausing slightly? every so often and the slight pause is superheating the acrylic? Anyone else ever seen anything like this? I haven't had a chance yet to run the machine to see what it does during this.

I have another problem I will take pictures of and post. It definitely is my day for problems.

dscn1177.jpgacrylic crack 1.jpg

[Dave Sheldrake]

Looks like backscatter Mark, what kind of cutting bed are you using?

cheers

Dave

[David Somers]

Mark,

I am afraid I am no help with a question like this. Sorry..... I am curious though. Do many engravers keep a scope on hand? (dissecting I assume?) I have a dissecting scope with a 3rd ocular for photographing/video work, along with a compound scope and a boroscope. All are amazingly handy for a variety of things from just plain useful to just plain being curious. I was surprised to see someone else with one though. People look at me like I am a mad scientist when they realize I have them.

Dave

[Dan Hintz]

Looks like backscatter Mark, what kind of cutting bed are you using?

Dang, beat me to it, Dave...

I'm going to guess it's an aluminum grid.

[Dave Sheldrake]

the spacing looks about right Dan

cheers

Dave

[Mike Null]

I would suspect the same thing looking at the first picture but the second one leads me to think there is an issue with the artwork. I would open the file again and check the number and proximity of the nodes.

[Chuck Stone]

I just made a grid and overlaid it on the photo. Seems to line up pretty well..

[Joe Pelonio]

In the second picture, it also looks like it could be a reaction to cleaning with a solvent, though normally that will result in actual cracks. Denatured Alcohol, for example will cause that. If it's flashback, and the artwork is ok, try applying transfer tape to both sides instead of the original plastic, and mist both sides with water before cutting. You can also insert pins (even tinker toy pegs) into the honeycomb to raise up the material.