I'm experimenting with cutting pink and blue styrofoam from the local hardware store. The pink is more open in structure, is harder than the blue and seems to give more consistent results.
I decided to compare climb and conventional milling, as I noticed when I used a mix of both, I was getting varied results.
I used a 2 flute .25" flat end carbide bit. 4000 rpm (max on my machine) at 100 IPM. All groves were milled to a depth of .3". On all images, the top groove is .10" per pass. The middle is .15". The bottom is .3" all at once.
The part that surprises me is that climb machining is supposed to give better results, yet that is not the case in these examples.