Adaptors like BT and HSK tool holders

Tool holders are used to adapt tools of different shapes and sizes accurately and securely to a milling machine spindle. Shanks are shaped to fit various standard machine tapers such as R8, NT 40, CAT 40, and BT 40.
The successful application of milling depends on how well the tool is supported by the tool holder. To achieve best results an end mill must be mounted concentric in a tool holder.