Step drills has two or more different drilling diameters
[Upper image] This drill is used to create a hole with a smaller diameter at the bottom and larger in the upper parts in a single operation.
Since these types of holes are quite common, we do not count this type of drill as a custom drill, even if the production is based on specific customer needs.
The step to the larger diameter can be angled if the hole is to be threaded or flat if the purpose is to recline a flat screw head.
The drill type can be manufactured as a solid drill or with interchangeable inserts.
[Bottom image] Step drill is also the term for a tool that can drill different hole diameters in sheet metal. The deeper you drill, the larger the hole diameter gets.