That's pretty much what I did on the handlepost, using a Dremel metal cutting bur. On the seat tube, I used a smooth cylindrical steel tool in the Dremel at high speed to "treat" the cut aluminum... which I call "burnishing".
Off topic:
In dentistry, a "chamfer" is the term used for the finish line between restorative materials and a tooth. The material has to be able to take and hold a sharp edge; metals, especially gold alloys, work well with a chamfer finish line.
"Burnishing" means applying pressure with a smooth metal instrument to a metal chamfer to deform it into tight contact with the tooth, forming a very close fit. This works especially well with gold.
Porcelain and some other materials work better with "butt" joints.
Here endeth the lesson. I think we both have the same basic understanding!