The air assist is critical for keeping flare-ups at bay, mitigating smoke, helping keep the lens cleaner and cooler (it really shouldn't get that hot if it is in proper order anyway), and, when cutting, catalyzing the ablation of material and evacuating the debris field through the bottom of the substrate and out the downdraft exhaust.
THIS ARTICLE IS MEANT ONLY FOR THOSE USING AN EXTERNAL AIR COMPRESSOR
STOCK AIR PUMPS WILL NOT OUTPUT A PRESSURE THAT WILL REGISTER WELL
Here is more on external air: Thunder Laser External Air Compressor Guidelines
Other than sound, feel, and maybe little bit of napkin math, there is no real way to apply a metric without a gauge. You can monitor the pressure at any point in the air assist system... the question is, which point?
Gary Wiant measures at each stage and outlines his setup and parts list here:
Here is his part list:
I chose to monitor the line going to the nozzle upstream of everything else because that is where the reading will be close the nozzle pressure. I am using an SMC ISE30A digital pressure switch that was used on the Mars series lasers:
Here is the digital pressure gauge mounted and displaying psi. i can set a lower limit and the display goes red if that limit is reached. it can also trigger an output when in alarm state. I am not going to signal the dsp to interrupt for low air assist pressures air but it is an option. Here is the link: https://www.smcpneumatics.com/ISE30A-N01-N-L.html