Thanks for answers, appreciate it.
I know I was running prob abv recommended speeds with the Makita, not having the rough equivalency chart at the time, so wonder if that is why my MDF machining turns out furry. Was a brand new 1/4" end mill for the rough cut, and a 1/8" ball for the final, but maybe I am not tweaking things quite right, yet. (Frankly, can’t remember if up cut or down cut bits.)
Ah, an hour or so is more like it. And the ‘smoothness’ issue you were talking about (obviously important to keep the yarns from fraying/wearing/fuzzing), I was wondering, that if you did use acrylic (not much experience, some small things here and there), whether you could flame-polish the slots with a torch or whatever, OR, if that would cause the slender openings to warp or deform too much.