The problem with pine for fine detail is that the grain is very large, very long, and very straight, as well as being very soft. It’s totally fine in structural timber, but for fine detail work it’s going to be very hard to cut that detail without chipping out long fibers, when you’re using a spinning tool. Basically, every characteristic of the wood is fighting your desire to do fine detail work.
However, you can do a few things:
- Higher speed.
- Very sharp bit.
- Very shallow passes.
Doing this will allow your router bit to actually sever the fibers, instead of pulling them up (causing tear-out).
If you want to do fine engraving, you should look at harder woods; something at least like poplar, if not more robust (like oak, walnut, etc.).