It does the same thing. Always cutting a slope to one side. I don’t agree with it being a melting issue or it wouldn’t be uniform over every cut and where I cut in the length of material would also impact it.
If it is melting (always to one side) then it has to do with the laser’s limitations and not the material.
remember, your laser beam isn’t a flat shape. it’s a conical hour glass. the focal point is generally on the surface. so depending on the focal length a lens is set at and the thickness of your material, you will always have some slope in your cut. i don’t know how much of an angle you’re seeing, but that could account for some of it.
as far as melting on 1/2" acrylic, you’re definitely going to get some slump cutting it as slow as you need to on a 40w laser. i haven’t gotten the same kind of clean cuts on the GF that i do on the 75w universal. there’s just not enough power to go through quickly enough to avoid some of that heat melt.
And even that’s “ideally”. There’s no guarantee that we’re starting with a uniformly circular diffuse laser before focusing down, the effective shape might not be a perfect cone but maybe some sort of oblong thing that I don’t even know how to name.
not sure what that gets you. you can manually change the focal point whether the tray is in there or not.
that 5w wouldn’t make as much difference as you think. 40w or 45w lasers are not the best tools for 1/2" acrylic. it can work, but you’re really pushing the limits of that power level and you’ll have to live with the downsides.
… and here’s an example of how focus height can change the cut (end view of 3/8" maple which is actually .39"). Each of these pairs of cuts are at the same speed, but the right cut is focused on the surface, the left (deeper) one is focused at 1/2 that height: