3. Drills

3.1 Tool selection

The first question to answer when choosing a tool is whether it should be an indexable or regrindable insert drill. As the first of these two types of drill cannot be used for small-diameter holes, the choice in such a case must necessarily be a resharpenable drill. In any case, it's a good idea to start by considering the diameter of the hole before choosing the appropriate tool.

• Small-diameter holes

  Resharpenable drills with Delta geometry (Sandvik-Coromant nomenclature) are available in three versions, with partially overlapping diameter ranges (figure 27...