I have a 60W Chinese laser etcher with a Ruida controller. I am running Lightburn. I am trying to etch glass cylinders using a rotary attachment. It is a cylinder style rotary. I have calculated my steps per rotation by creating a line box in Lightburn, and setting rotary numbers accordingly: SPR - 1180.5. Roller diameter - 24mm. object diameter - 38mm. Circumference - 119.381. Running my laser at speed - 100 and power - 20%.
To test the calibration, I created a box and sized it to fit the cylinder - 119.381mm high x 80mm wide. The box etched perfectly with the horizontal lines matching exactly.
Then I created a graphic in photoshop and brought it into Lightburn. I set the size at the exact same size, in fact setting it precisely over the box I created earlier.
The graphic etched with a 6mm gap! But the box still etched perfectly.
How can two different objects that are exactly the same size under exactly the same rotary settings etch at different sizes?? The only thing I can think of, the only variable that I cannot account for, is that etching the box takes seconds and only four movements while the graphic takes 1200 movements and about 20 minutes. Does this mean my rotary is inaccurate?