Has anyone found an issue of low power engraves going lighter mid-engrave?
I had run a test of an olive art drawing/engraving converted to BMP using the 50% threshold, so there is only black/white data in the source file.
I first ran test runs on scrap of same manufacturer card stock to get a feel for quality/speed tradeoffs to get the effect I was looking for. I chose #3 which has speed 300; power 3; density 100 (dots); 125 lpi. This yields an 8x10 engrave time about 1hr45.
I chose a medium olive stock for my final project, but found that I had non-uniform art contrast across the sheet. It started off saturated like intended, then went lighter for a while, and then ended off sort of between intended engrave contrast/density.
So while uneven across sheet, I was concerned that difference was exacerbated by stock color. So I began re-running the file this morning on a dark olive (same manufacturer). (Though the olive looks about the same in this photo under the bright Glowforge lights, it is noticeably darker in person.)
It started out with the art looking much more contrasted, like hoped for, but turned “washed out” even quicker than yesterday’s engrave run:
And here are the two engraves after finished—with contrast issues showing up in different areas of the sheet despite the same art:
Does anyone have any idea of what may be going on? The sheet is held down by multiple hold down pins so the sheet is laying flat and is unmoved by the fan. All lenses have been cleaned two days ago and have run a couple other engrave/cut projects; the PG Plywood and Acrylic have generally been performing as expected:
So I am stumped regarding these low power engraves. It’s frustrating to waste material costs – though on textured card stock is cheaper than PG wood – but more frustrating to have the time wasted, too.