.25" Black Delrin I succeeded with great results using this method (borrowed the idea from above):
Pass 1 500 @ 95% - to get that first score down
Pass 2 300 @ Full
Pass 3 100 @ 100%
That first score at higher speed get’s it past the surface with minimal candle and lower smoke, that 2nd pass cuts it down to 1/2 way and since the surface is breached the separation is starting to maximize.
Its that last pass that really breaks through the 2nd half leaving clean straight edges and low melting on the back side. I tried other settings and I ended up having a lot of melt on the back side where the honeycomb meets delrin.