I'm milling small parts out of 7075 on a 3 axis cnc with a high speed spindle (6k to 24k). Bearing pocket sizes range from 8mm to 25mm, all have a square bottom lip. Rpm range means no boring. Up to 10mm or so I use a 1/8 3 flute carbide zrn, for over 10mm I use a 1/4, same type. Here's where I have issues, I like to get a nice perfect press fit so I prefer to start a bit tight and sneak up on it. Once I'm taking very small bites for final sizing, it doesn't like to bite. Seems like I have to overshoot by quite a ways to get to proper size. If I go for dead on size right away when it has a decent step over to cut, sometimes it's perfect but there's possibility of over shooting and scrapping a part. I understand that cutters like to take an actual chip or they tend to rub instead of cut. My current method of sneaking up does work eventually, just seems to take forever since it doesn't like to cut with such a small step over and sometimes I end up with a slight taper since the tool is deflecting as it resists cutting.
What would be the best approach for handling this? Would a different type of endmill be better at taking very light cuts? I've heard hss can have a sharper edge than carbide, but less rigid so maybe no help there. I could probably be close enough 90 percent of the time if I measure tool run out after loading it and then go for dead on first try but some of these parts are very complex with multiple setups and holding positions so I prefer to slowly sneak up to make sure I don't overshoot.
Is there a better way to do this or a better tool than what I'm using? Any suggestions are much appreciated