Hi Gang - I'm at my wits end with my latest job. I have a few hundred pint glasses to do and my laser isn't cooperating with me, or I'm not cooperating with my laser (the latter is more likely).
On this job the trouble I'm having isn't 100% of the time, but it is occurring on at least 8 out of every 10 glasses I'm running.
The trouble is the engraving isn't consistent across the entire surface of the graphic. You can see in the example images that the leading edge of the art has a different surface finish than the rest of the engraved area.
The one consistent theme with the trouble I'm having is that it's always on the leading edge of the engraved area. That said it doesn't always occur at the same point on the art and it happens to differing degrees as seen in the images.
IMG_0442.jpg IMG_0443.jpg IMG_0445.jpg IMG_0447.jpg IMG_0446.jpg
Now for my settings and technique. I've tried many different settings and techniques in an effort to improve or at least make the trouble consistent so I can begin tweaking settings, but up until now the settings and techniques have not shown much in the way of a difference to the outcome.
I am using a Trotec 400 Flexx (120W CO2) with the rotary accessory and using the hot dog roller attachment (not the clamp).
I've tried settings from 90% power at 100 speed to 75% power at 65 speed - No real difference
I've tried it as vector art and raster art (using CorelDraw) with Ordered Dithered from 333dpi to 1200dpi - No real difference
I've tried liquid soap on the surface, wet newspaper and dry - No real difference
I've cleaned the mirror and lens (2.85" flexx lens) at the laser head - No real difference
At this point I am not getting consistent results to where I can start chasing down what's really happening here.
I would point out that when I started running the pint glasses, I really only saw this occurring subtly on the first paw print, but since then it has gotten worse.