I made an interesting discovery yesterday; all plywood is not created equal. I’ve been using 3mm Russian birch from the same supplier for years and now, due to supply chain interruptions or whatever, it is no longer available and won’t be available until late 2021. (If you want to see something that’ll take your breath away, go see what a 2x4 cost at Lowes these days). Anyhow I substituted 2.6 mil plywood from another manufacturer and much to my dismay, I have discovered that its cutting performance is horrendous. It has a different core which results in ablation and charring which attenuates the cutting power. Initially, my instincts suspected a laser tube failure, but I checked cutting performance with a piece of old 3mil stock and it cut like butter.
Point is, seemingly similar products can have result in huge variations in performance which might lead you in the wrong direction.
This is what I THINK is going on…the 3mm Russian birch that I typically use has a double-sided finish. The core section is comparatively very thin (and I believe just binder and glue) making Russian birch mostly honest-to-god wood. This other stuff I tried, even though slightly thinner, was more core than wood.
I’ve been following this forum for a long time and guys routinely complain about cutting performance. The lightbulb went off for me yesterday; seemingly similar materials can have radically different characteristics that dramatically impact laser performance.