Yeah, that's where I'm confused. I konw the oxide layer will grow, but my understanding of it is that it grows *into* the material. Your saying that screws can become too tight seems to be at odds with that, though.
And that could be a problem, because giving threaded holes some wear resistance is something I want. Though my major concern is the wear of the large 1.25" hole from repeated toolholder changes.
I'm not doing hard anodizing, just the regular DIY type of anodizing with a quick etch, anodize for 1-2 hours, dye, and seal. I'm going to try the dye, but it's not that important for me as I just want it to distinguish one toolholder from another.