Returning to the clamp example from this previous article, let's take a closer look at how the bolt holes were made through the side of the clamp.
In the photo below of the two clamp halves, you will notice that the clamp has indendations along the cut line where the bolt holes go. This makes it easier for a drill press operator to precisely locate the position of the holes.
Illustration : The two halves of the split clamp before the bolt hole
is drilled in the cut edge. Note the indentation which indicates
where the bolt holes will be located.
Illustration : Drilling a bolt hole in the cut edge of the clamp with a drill press.
The indentation in the cut line helps locate the correct spot for the hole.
A similar indentation in the cut line can be used to mark the location of blind holes or other features created by secondary operations.