[Litografa]

I know, but if you want make tests - it's ok test with inert gas, and use nitrogen for commercial orders.

[avetek]

Aussiemate

I have an 80watt laser and I can assure you that it will not cut 9 mm ply - with the standard lens - it will just cut 7mm ply. With a 3" lens it will cut the 6 mm ply reasonably easily. The charring that most plywoods have is due ,in my experience, to the glue (water resistant) - I only use indoor grade ply which cuts fine - this has a different glue that doesnt char.
I would think that you will need at least 1oo - 120 watts and buy a 3 in lens - this will give you a longer focal length , less kerf and hence a stronger cutting beam - I can cut at about twice the speed with the 3" lens vs the 2" std lens

Regards,

[Litografa]

Are you sure about 3" lens? Standart sizes are 1.5", 2" and 4"