The Dormer First stage rotary burr is used for removes broken bolt. First stage broken bolt removal has carbide tipped with toughened and hardened steel shank and bright finish. When a bolt is broken and needs to be extracted first use P100 to flatten the broken bolt surface. Secondly use P101. This series of burrs makes sure the threaded hole is not damaged when removing the broken piece.

End cut burr end
Dormer standards
Single cut flute style
Bolt removal cut geometry
Cylinder with end cut design