Patents Assigned to Thomas Grismer
  • Patent number: 5094572
    Abstract: A flat drill for boring holes through hard metals and high heat resistance materials such as hard metal and fiberglass. The flute or fluid portion forms a spade with slightly cylindrically concave faces which tend to distally converge. The cutting edges at the base of the drill have a negative rake angle, but a relatively high clearance for this type of drill. The lateral leading edges have a positive rake angle, but are strengthened by cylindrically convex flanks. Nose splits form a small but relatively keen small central burrowing edge which stabilizes the drill.
    Type: Grant
    Filed: December 4, 1989
    Date of Patent: March 10, 1992
    Assignee: Thomas Grismer
    Inventors: Herbert W. Alsbury, Robert A. Sheffler