WHAT causes this odd stridation?

[Debbie Sweet]

Hello

I have been experiencing this "streaking" "stridation" effect. Has anyone ever had this?

I have changed settings and raised the PPI but nothing is working except for sometimes making it less noticeable or more pronounced. Sometimes the area has a line (like the 2) or half the area is lighter and darker engraving (the 9)
I thought it was happening at a certain placing on the bed but I've moved the art and it still is happening. in the same place on the artwork -- it seems the ends of the art.

Any help would be greatly appreciated -- I'm have to do redo the work and driving me crazy:(
THANK YOU!!382864

[Keith Downing]

Hey Debbie,

It will help people offer solutions if you will list what type of laser you are running. Answers will differ greatly based on that. You might also want to put your laser type in your signature (seen below) so that you don't have to post it every time.

Also, can you try a better picture of your problem. I can't see anything in this picture that looks abnormal.

[Keith Downing]

On a normal monitor now and I can see a horizontal line near the middle of the two.

My first guess would be you might be getting some heat buildup. Are you using air assist while running these? And again, what laser is this on?

[Debbie Sweet]

Thank you Keith

I can't find how to put my laser info in the signature but I have a GCC Explorer 60W with a Coherent Gem laser tube. It is air assisted.
I found one trick to alleviate it which makes no sense why it works -- I put a little long thick line on the outside of the area -- Meaning these were table numbers so the line/bar was on the other side of the cut line of the rectangle. But I hate putting this bar on all my art. It just happens on solid areas - if it's on other areas I can't see it like it shows on a solid area.

[Keith Downing]

I can't find how to put my laser info in the signature but I have a GCC Explorer 60W with a Coherent Gem laser tube.

At the top of this page, in the menu bar at the very top, click Settings. Then about halfway down the left menu on the next page you'll see "Edit Signature".



It is air assisted.
I found one trick to alleviate it which makes no sense why it works -- I put a little long thick line on the outside of the area -- Meaning these were table numbers so the line/bar was on the other side of the cut line of the rectangle. But I hate putting this bar on all my art. It just happens on solid areas - if it's on other areas I can't see it like it shows on a solid area.


If the line you're adding is making the passes longer it could very well be heat buildup that's causing the difference.

There are two ways that I can think of to determine if this is the cause. One is to greatly increase your air assist on the entire piece.

If that is not possible, you could try pausing your machine 4 or 5 times during the engraving and waiting about 30 seconds each time, just as a test. Of course, I would not recommend that as a solution, just for troubleshooting.

I've never had this exact problem with acrylic, but I have had something similar happen with cermark where it was getting too hot and created the exact same little patch of inconsistency in the graphic.

[Kev Williams]

What Y resolution are you running? If 500 or above, try 380 (or whatever you're GCC's next lower res setting is)--

Another trick to try, and I'm assuming your print driver is similar to mine, is to engrave in black/white mode... res in the 400 range, for color try 70% gray, or just plain green works good as it translates somewhere to around 70-80% in grayscale... In the 'raster' settings try a 4x4 "dot" pattern. Try on some scrap first, but the dithering should help with hot spots, and produce a nice consistent 'frost' look...