Well time for an update here with my quest for consistant depth when engraving....
I am lasering into 1/8" baltic birch ply, all taped down to keep things flat. I am engraving 24 identical pieces: 4 columns X 6 rows on a single sheet. I am still using the old mirror as Epilog sent me the wrong one this week. I cleaned everything up and rotated the damaged mirror to see if that would make a difference. I did an alignment and leveled the table as well. The rails and lens carriage were all cleaned up as well before this project was started.What I see now is the engraving is looking distorted or bold looking going up the column from piece to piece in the exact same spot. Looking over to the next row is the same thing but in a different area of engraving. SO it appears almost like a band that runs up the entire row. The vertical bands occur every 1 1/2" across the table. So it definitely has a repeating pattern at the exact same spot running through it. Has anyone seen a vertical banding effect with their laser? I did 4 sheets of 12" X 16" and they are all identical as far as the placement of the banding.
I know I will eventually get this pinned down with the help of the members of this forum... New mirror should be here this week, but not sure if that will solve the problem.