Patent ID: 7887269
Filing Date: 2011-02-15
Classification: B27G,Y10T

Abstract:
1. A spade bit, comprising: a shaft defining an axis about which the spade bit is configured to be rotated; a blade attached to said shaft and having a first blade portion and a second blade portion, wherein (i) said first blade portion defines a first concave leading face portion and a first convex trailing face portion, and (ii) said second blade portion defines a second concave leading face portion and a second convex trailing face portion, wherein (i) said first blade portion includes a first shoulder that defines a first cutting edge portion, and (ii) said second blade portion includes a second shoulder that defines a second cutting edge portion, wherein (i) said first cutting edge portion lies on a first border portion of said first concave leading face portion, and (ii) said second cutting edge portion lies on a second border portion of said second concave leading face portion, wherein said first cutting edge portion and said second cutting edge portion both lie in a plane P wherein (i) an area A wherein (i) an area A