Problem with focus lens 130W CO2

Hello, for some reason my 130W CO2 seems to cut plywood (3 to 6mm) better with a 38.1 focus lens than a 50.8 or 63.5mm. I thought that 50.8 or 63.5mm would have more power to cut. I tried cutting a 5.5mm plywood sheet using al three lenses with the same power, speed and with their respective focal height for each lens, but the 38.1 was able to cut through the material and the other 2 didn’t. Not sure what I am doing wrong! I wanted to use less power and increasing the speed of my cuttings.

While the depth of focus increases with longer focal lengths, so does the spot size (and thus minimum kerf). This means that the power per unit of area is lower, so you need higher power to cut with a longer focal length, though you get a straighter wall on your cut. @NedMan just posted this:


Thank you Michael,

It makes a lot of sense!