Alan showed us a few tricks in the latest version of Lightburn.
Travis showed a few wonderful hacks of the Chinese RuiDa lasers.
| 00:36:16 | SD Fine Woodworkers: | Marsh Stencil Ink |
|---|---|---|
| 00:50:18 | Alan L: | Air Assist |
| 01:03:32 | SD Fine Woodworkers: | https://www.youtube.com/channel/UCqCyShJXqnElPTUnxX0mD5A |
Alan, I like the “shelf” you made for holding up your flow meter and current meter. 
LOL
Sounds like it would be just as easy to add a 2nd flow “sensor” for redundancy. After all, that’s what is inside the chiller, ie a 2nd flow sensor.
Because it is less likely 2 flow sensors will fail at the same time and in the same way the easy solution, besides the visualization is to install a 2nd flow sensor.
BTW, my K40 has no flow sensor( some K40D models do ) so I put a visual indicator with built-in temperature sensor early on.
On the air assist, I use a shop compressor regulated to 80PSI at the compressor and then I have another regulator at the K40 regulating down to 5PSI. BUT, I only use the laser head “nozzle cone” for keeping the lens clean and I have an air assist tube which provides a very small stream of air at the cut.
I like the idea of a fish air pump for the nozzle cone and controlling the “air assist” tube for when it’s needed.
milliAmpere meter is one of the MUST HAVE for the K40. The $300 K40 only has the mA meter and a knob to adjust power but the “higher end” K40 have a digital control. BUT, that digital control is very inaccurate and most of the time anything over 40% setting on the control panel is over driving the tube. So because of this and how many people have killed their tubes in only a few months, it’s one of the MUST HAVE upgrades and I recommend they not use the machine until they either measure the current with a multi-meter or install the mA meter.