When doing laser designs using Fixed Power, the laser power is being set for each element of the design using the following GCode:
; Laser: setting power
M3 P24 S61
This causes the laser to turn on for 1ms and then switch off. On sensitive materials (such as Rowmark Flexibrass engraving laminate) this can be enough to leave a tiny burnt dot in the centre of the material.
When using multiple elements, this happens for each element of the design, making the burn more obvious with each element.
I am currently working around this by not using fixed power, using multiple design passes for designs that require different power settings for different design elements, and masking the laser with a piece of cardboard when I change the power. However, this is a pretty major annoyance.
When using Fixed Power, rather than using the above quoted GCode to set the power, could the power instead be set on the first M3 command of the actual design being engraved? This would cause the burn from setting the power to be made on the material at a point that is going to be etched anyway, and should eliminate the impact of this.