This link is about measuring the kerf. @BillieRuben built a vernier scale kerf tool. It’s pretty slick…
If you follow the link to my tool you’ll see that I measure about 0.164 for the kerf on 3mm basswood. Considering these were done with a 2" lens, which has a spot size of ~0.10mm. The proper kerf would be 1/2 the measured kerf 0.082mm… You want half the kerf applied to each side of the cut…
Your beam size or kerf would have to be 1.8mm, something is wrong here…
If you are making a dot that is smaller than 0.10mm you’re doing good for a co2. Do you know what length of lens is in that polar?