Home built machine using the Lasertree K60 60W diode laser. The clock is 332mmx500mm. Speed is 3000mm/min at 60% power with the laser on the 40W setting. Scan angle is 90 degrees. This is the first time I’ve engraved the majority of the material. Could the air assist be causing this issue? It’s strange in that there are multiple “bands” appearing. It kinda looks cool, but it’s not an effect I want!
I’m wondering if turning down the power and doing multiple passes might resolve it.
My call is that you are seeing different density in the wood aka: wood grain. See how the odd color bands are not at 90 degrees? That is a material issue rather than a laser issue.
What flavor of wood are you using? More passes at less power can reduce the difference between the bands of grain, as does using different wood species.
I run my rotary at 90 degree angle, but don’t usually run the flat diode plotter at 90 degrees unless I open the lines per inch to achieve a desired texture.
The grain runs the same direction the laser is moving. The pattern of the ghost lines matches the material that’s not being engraved.
Are these the ghosts that you are talking about? I see those on Y axis when the acceleration is very high and the speed is also high. I have called that artifact “ringing”, it is indicative of a harmonic vibration induced in the gantry and amplified by the mass of the gantry. This is one of the reasons that the gurus on this forum do not like to use 90 degree scan angle. Try it again on a 00 degree angle and see if you get the same “ghosts.”
I plan to do it again with the scan angle at 0.
The head was moving in a single pass from top to bottom, non stop, all 500mm in each pass, in line with the grain. It wasn’t engraving the image in parts.
I found that the “white space” speed was 6000mm/min, so it was toggling between 3000 when engraving & 6000 when it wasn’t. I set the white space speed to 3000 to match the engraving speed, & the problem went away. This was with the scan angle still at 90 degrees.
For this particular project, having the scan angle at 90 degrees isn’t a problem now that the head is moving at a constant speed from top to bottom & back, but I now understand why using 0 degrees is better overall.
Thanks Jim!
Glad to know how you fixed it. There are many skins on that cat, and just as many ways to fix the problems.
I really appreciate the follow up post 
