As I’m on the topic now:
I replaced also the air compressor (now airbrushcompressor 50l/min@6bar and 6 liter buffertank) as the airflow was at its limits with the 35l/min one. The results are way better now. Less black residue when cutting wood.
Compressor is always on when the laser is on and delivers a minimal air flow to keep the lens clean. The valve bypasses the reduction for the minimal airflow and delivers high flow when cutting wood, leather.
The X-stepper also got some extra cooling : alu profile with a 40mm fan installed.