No one has seem to found the answer to these stubborn bumps.
Lens checked if clean
Calibrated jump settings
Adjusted parameters i.e. power, speed, kHz, line intervals
Used clean up passes
Air flow
I have been doing 3D slice engravings (256 and 512 passes) where these bumps have shown in the same area of every coin, of every design. These only began happening when i switched from my 110mm lens to my 70mm lens with the coin being set in a different main location on my working table for each lens.
I have an air pump that pushes particulates from my engraved coin into the exhaust that is sucking in air. Both are close to the coin. Funnily enough, the bump spots seem to be in part of the coin that is closest to the air pump that is pushing out air.
I have unscrewed the lens 1/8 and 1/4 turns, each for 256 3D slices to see if the bumps will move. They both stayed relatively in the same area but the 1/4 turn 3D slice produced bumps that are more spread. My assumption is that brass particulates were dragged across the coin and hardened when engraved, from my exhaust’s improved suction for that 3D slice from my adjustments.
My last hope which is has not been attempted is to clean my galvo mirrors. I have watched quite a few videos on how to do this and noticed that all galvo mirrors in the videos are clean and blank whereas mine have writing on them. Possibly another clue.
These are all the clues i have that i know of. Feel free to ask me anything as this is the most stubborn issue i have faced. I have yet to receive a reply from the manufacturer. Also, i only have my 70mm lens to use at the moment. my 110mm got damaged due to debris inside the lens and other lens have been ordered.
Machine: 30W JPT-LP LiteMarker Fiber Laser
Thank you all in advance. I hope to hear from you all!
Based on my telescope experience, those are front-surface mirrors. (Home mirrors are back-surface.
I have never seen a green front surface mirror. Is there a chance that is a protective film that did not get removed? and yes, there should be NO writing on the mirror surface.
If it is not a protective plastic film, be VERY careful cleaning those mirrors. If you scratch one, get your checkbook out.
Thank you for your valuable insight Mikey! I have spoken to the company where i got my machine from and APPARENTLY this does not impact engravings and that they also have it on theirs… I seriously have my doubts. Before i do anything, i’m going to see if i can contact the actual manufacturers of my machine to see what they think…
I think you are correct with the assumption here. the 1/4 turn would change the focus plane slightly.
How frequently do you do clean up passes? What settings do you use for them? Do you increment the angle per cleanup pass?
What’s the final depth?
One thing you can try is running one without any air in/out. If it the case of particles being remelted onto the surface, I’d expect a more uniform distribution of bumps. Doing so would give useful data on how the air plays into the overall problem. Obviously not recommended for long term!
