Pencil milling
Introduction
[thumb\|300px\|Pencil toolpath diagram](/wiki/Image:Pencil2.png "Pencil2.png")
[thumb\|300px\|Pencil milling diagram](/wiki/Image:Pencil3.png "Pencil3.png")

**Pencil milling** is a cleanup toolpath generated by [computer\-aided manufacturing](/wiki/Computer-aided_manufacturing "Computer-aided manufacturing") (CAM) programs to machine internal corners and fillets with smaller radius tools to remove the remaining material that are inaccessible with larger tools used for previous roughing, semi\-finishing, and finishing toolpaths. The name comes from the way that a pencil could naturally be drawn along these corners. It is sometimes called a rolling ball toolpath.

Often a [constant step\-over passes](/wiki/Constant_step-over_passes "Constant step-over passes") are derived from single pencil pass to create parallel pencil passes that are very good for cleaning up corners and fillets where excess material remains from a bigger cutter.


How does pencil milling affect the overall shape of an object?