The lens holder on my new laser has two places to install the lens (one on the upper end / one on the lower end). My old laser did not have this. My old laser, I always used 63.5mm (2.5 inch) focal length lenses. Therefore, the only workable position for that lens would have been in the lower end of the cone.
In my new laser, I have been using 101.6mm (4") focal length lenses. The lens is placed in the UPPER end of the cone. In this configuration, the cone tip is roughly 8mm from the work piece. Ironically, on my old laser, when using the 63.5mm lens in the LOWER end of the cone, the cone tip was roughly 8mm from the work piece.
So then I got to thinking… should I try out the 101.6mm lens in the lower holder? I like the idea if having more clearance from my work piece for sure. It would allow for more options for hold downs as well.
I use conditioned (dried) compressed air to my laser (on an independent regulator), so where I see that I may need to increase the flow / pressure to prevent combustion - I have that ability. The added distance would probably not allow for as fine of a stream of air. But testing will have to see if that makes a negative impact.
I am curious if anyone else has tried this. Below is a picture representing the option: