I wanted to try air assist with a product from expocncondemand.com . The claim is that the new lens helps with the focus and it provides a direct connection for a air hose.

I think this product has some potential but I encountered a couple of issues related to my setup. The first one is after adjusting the focus, the nozzle is extremely close to the material. It's not a problem when everything is perfectly flat but when cutting thin sheets of plywood they always have a bend. Also, because of the "T" design of my setup and the heavy weight of the laser module, there's 2mm difference in height between the back position and the front position. With the original lens, it's not a big deal because the operating window is bigger then that but with the G8 lens I had some trouble.

The other issue is that my enclosure is very low profile and I need to elevate the laser module 40mm above the surface compared to around 25mm with the original lens. And the module can't do a homing without hitting the frame of the enclosure. 

With the original lens, I can even cut 8mm plywood without changing the height while with the new lens, I have to adjust it for every new material height.

I also tried with the air assist by connecting a aquarium air pump but I think my flow was not high enough because it didn't improve much.

Anyhow, I put everything back to the original setup and adjusted the focus again. I must say that even without any focused air assist, the combination of the fan from the laser module and the strong vacuum created by the air extractor is enough to make a nice cut.

Here's some examples

8 mm pine : 270mm/min @100% - 6 passes

The front has hardly any burnt mark

The sides are not charred - but that's only true when using raw pine

The back is quite burnt. I probably need one less pass or get a better grid support.