Lightpath alignment on DIY CO2 Laser setup

[Wayne Rees]

Is your Laser tube perfectly parallel to the y rail, and is the y rail perfectly parallel from front to back, if it is hitting the same spot on 3 corners first check your y rails are parallel and there is no twist across the frame. if you raise the anode end ( not the output end) the beam should drop slightly at the point you are having an issue with, you then need to re run the alignment procedure all over again, you only need to raise it half the amount of error you are experiencing

[Jefferybarf]

sounds like a twisted bed, try X 650 Y 0 and see if the beam is 1,5 mm high.