David Marshall Barr

US Patent:

50727150, Dec 17, 1991

Filed:

Apr 25, 1990

Appl. No.:

7/514152

Inventors:

David W. Barr - Houston TX

International Classification:

F41B 302

US Classification:

124 201

Abstract:

An improved slingshot includes an elongated mainframe and a fork assembly pivotally mounted about a transverse axis at the forward end of the mainframe. The fork assembly includes a pivotal flip-fork resiliently biased to normally assume a lowered neutral non-shooting position in which is lies below the path of flight of a projectile shot by the slingshot. The flip-fork is pivotally movable against the bias to an upright shooting position upon stretching of a power band connected to the flip-fork. Upon being moved to its shooting position, the flip-fork stores energy in addition to that being stored in the elastic power band as the latter is stretched to load the slingshot. The mainframe of the slingshot includes a hand grip located between forward and rearward ends of the mainframe and rearward and forward frame portions extend respectively rearwardly and forwardly of the hand grip. The rearward frame portion is connected to a lower end of the hand grip for placement under a user's wrist and forearm when the hand grip is held by the user's hand, whereas the forward frame portion is connected to an upper end of the hand grip and extends inclined forwardly and downwardly therefrom so as to position the forward end of the mainframe on a centerline through a user's arm and hand holding the slingshot.

US Patent:

59608960, Oct 5, 1999

Filed:

Sep 8, 1997

Appl. No.:

8/925883

Inventors:

David H. Barr - The Woodlands TX
Danny E. Scott - Montgomery TX
Craig H. Cooley - South Ogden UT

Assignee:

Baker Hughes Incorporated - Houston TX

International Classification:

E21B 1046

US Classification:

175431

Abstract:

A rotary drag bit equipped with a plurality of cutters, each including a superabrasive cutting face, wherein cutters carried by the bit have at least two differing chamfer geometries adjacent their cutting edges. Chamfer geometries are selected according to location on the face of the bit responsive to the relative ease or difficulty of cutting formation rock and the severity of dynamic loading at that location. The bit face may be characterized as comprising at least two areas or regions bearing cutters having differing chamfer geometries to maximize rate of penetration of the bit while preserving cutter integrity when subjected to differing stresses and encountering zones of the formation exhibiting different strengths. Characteristics, such as hardness, abrasiveness and homogeneity, of the target formation or formations to be drilled by the bit may be considered when selecting appropriate chamfer geometries for the cutters allocated to cut each formation zone opposite the bit face.