An embodiment of a spade bit has straight grooves at a lead angle of 4 to 8 degrees placed on flat edges of the spade bit. In an alternative embodiment, a spade bit has two steps of straight grooves at a lead angle of 4 to 8 degrees placed on flat edges of the spade bit. In other alternative embodiments, a spade bit has tapered flat edge which have straight grooves at a lead angle of 4 to 8 degrees placed thereon. The straight grooves on the flat edges of the spade bits allow the spade bit to pull itself through the workpiece with a minimal amount of penetration. The flat edges of the spade bit may also have cutting surfaces for cleaning the hole and permitting the easy removal of the spade bit from the hole after drilling.
1. A spade bit comprising:
a blade portion having opposite first and second surfaces and a predetermined thickness of approximately between 0.085 and 0.095 inches, said predetermined thickness being defined by a distance between said first surface and said second surface, said blade portion further having opposite first and second side edges which extend from a front end of said blade portion to a rear end of said blade portion, at least a portion of said first and second side edges having grooves formed therein to define a grooved portion of said blade portion; and
a shaft attached to said blade portion.
2. A spade bit as defined in claim 1 , wherein said grooves formed in said first and second side edges of said grooved portion of said blade portion are straight grooves.
3. A spade bit as defined in claim 1 , wherein said grooves of said grooved portion are formed at a lead angle of approximately between four and eight degrees.
4. A spade bit as defined in claim 3 , wherein said grooves of said grooved portion are formed at a lead angle of approximately six degrees.
5. A spade bit as defined in claim 1 , wherein said predetermined thickness of said blade portion is approximately 0.093 inches.
6. A spade bit as defined in claim 1 , wherein said blade portion has a rear portion proximate to said rear end thereof, said rear portion being positioned between said grooved portion and said shaft, said first and second side edges of said blade portion at said rear portion thereof providing cutting edges.
7. A spade bit as defined in claim 6 , wherein said rear portion has a diameter which is larger than a diameter of said grooved portion.
8. A spade bit as defined in claim 1 , wherein said shaft is elongated and joined to said rear end of said blade portion.
9. A spade bit as defined in claim 1 , further including a spur, said spur being provided at a front end of said blade portion.
10. A spade bit as defined in claim 9 , wherein said spur is provided proximate said grooved portion.
11. A spade bit as defined in claim 1 , wherein said first and second side edges of said grooved portion taper from a second end thereof to a first end thereof, said first end being proximate to said front end of said blade portion, said second end being proximate to said rear end of said blade portion.
12. A spade bit as defined in claim 11 , wherein each of said grooves defines a pair of adjacent crests and a root between said adjacent crests, said grooved portion has a root diameter and a crest diameter proximate to said front end of said blade portion, said root diameter is defined as a distance between said root of said groove on said first side edge which is most proximate to said front end of said blade portion and said root of said groove on said second side edge which is most proximate to said front end of said blade portion, said crest diameter is defined as a distance between said crest of said groove on said first side edge which is most proximate to said front end of said blade portion and said crest of said groove on said second side edge which is most proximate to said front end of said blade portion, said blade portion has a front portion proximate to said front end thereof, said front portion being positioned between said front end and said grooved portion, said front portion having a predetermined diameter which is defined as a distance between said first side edge of said front portion and said second side edge of said front portion, said predetermined diameter of said front portion being equal to or greater than said root diameter, said predetermined diameter of said front portion being equal to or less than said crest diameter.
13. A spade bit as defined in claim 1 , wherein said first and second side edges of said grooved portion are stepped to define a first grooved section and a second grooved section, said first grooved section being positioned between said front end of said blade portion and said second grooved section, said second grooved section being positioned between said first grooved section and said rear end of said blade portion.
14. A spade bit as defined in claim 13 , wherein said first grooved portion has a predetermined diameter which is defined as a distance between said first and second side edges of said first grooved portion, and wherein said second grooved portion has a predetermined diameter which is defined as a distance between said first and second side edges of said second grooved portion, said predetermined diameter of said second grooved portion being larger than said predetermined diameter of said first grooved portion.
15. A spade bit as defined in claim 1 , wherein said blade portion has a front leading edge at said front end thereof, said front leading edge is at least partially sharpened in order to act as a cutting edge of said blade portion.
16. A spade bit comprising:
a shaft having a forward end and a rear end, said rear end of said shaft being configured to be received and held by a tool;
a spur having a forward end and a rear end, said forward end of said spur generally forming a point; and
a blade portion having,
a forward end and a rear end, said forward end of said blade portion being joined with said rear end of said spur, said rear end of said blade portion being joined with said forward end of said shaft,
first and second spaced-apart surfaces, said first and second surfaces being generally parallel, said first and second surfaces being spaced apart by a predetermined thickness of approximately between 0.085 and 0.095 inches,
first and second side edges which extend from said forward end of said blade portion to said rear end of said blade portion, and
first and second portions, said first portion extending from said forward end of said blade portion to said second portion of said blade portion, said second portion extending from said first portion of said blade portion to said rear end of said blade portion, said first portion having grooves formed therein along said first and second side edges thereof, a distance from said first side edge to said second side edge of said first portion being less than a distance from said first side edge to said second side edge of said second portion.
17. A spade bit as defined in claim 16 , wherein said grooves formed in said first and second side edges of said first portion of said blade portion are straight grooves which are formed at a lead angle of approximately between four and eight degrees.
18. A spade bit as defined in claim 16 , wherein said first and second side edges of said second portion are formed as cutting edges.
19. A spade bit as defined in claim 16 , wherein a cutting surface is provided between said spur and said blade portion.
20. A spade bit comprising:
a shaft having a forward end and a rear end, said rear end of said shaft being configured to be received and held by a tool;
a spur having a forward end and a rear end, said forward end of said spur generally forming a point; and
a blade portion having,
a forward end and a rear end, said forward end of said blade portion being joined with said rear end of said spur, said rear end of said blade portion being joined with said forward end of said shaft
first and second spaced-apart surfaces, said first and second surfaces being generally parallel, said first and second surfaces being spaced apart by a predetermined thickness of approximately between 0.085 and 0.095 inches,
first and second side edges which extend from said forward end of said blade portion to said rear end of said blade portion, and
first and second portions, said first portion extending from said forward end of said blade portion to said second portion of said blade portion, said second portion extending from said first portion of said blade portion to said rear end of said blade portion, said first portion having grooves formed therein along said first and second side edges thereof, said first portion being stepped to define a first grooved section and a second grooved section, said first grooved section extending from said forward end of said blade portion to said second grooved section, said second grooved section extending from said first grooved section to said second portion of said blade portion, a distance from said first side edge to said second side edge of said first grooved section being less than a distance from said first side edge to said second side edge of said second grooved section, a distance from said first side edge to said second side edge of said second grooved section being less than a distance from said first side edge to said second side edge of said second portion.
21. A spade bit as defined in claim 20 , wherein said grooves formed in said first and second side edges of said first portion are straight grooves which are formed at a lead angle of approximately between four and eight degrees.
22. A spade bit as defined in claim 20 , wherein said first and second side edges of said second portion are formed as cutting edges.
23. A spade bit as defined in claim 20 , wherein a cutting surface is provided between said spur and said blade portion.
24. A spade bit comprising:
a shaft having a forward end and a rear end, said rear end of said shaft being configured to be received and held by a tool;
a spur having a forward end and a rear end, said forward end of said spur generally forming a point; and
a blade portion having,
a forward end and a rear end, said forward end of said blade portion being joined with said rear end of said spur, said rear end of said blade portion being joined with said forward end of said shaft,
first and second spaced-apart surfaces, said first and second surfaces being generally parallel, said first and second surfaces being spaced apart by a predetermined thickness of approximately between 0.085 and 0.095 inches,
first and second side edges which extend from said forward end of said blade portion to said rear end of said blade portion, and
first and second portions, said first portion extending from said forward end of said blade portion to said second portion of said blade portion, said second portion extending from said first portion of said blade portion to said rear end of said blade portion, said first portion having grooves formed therein along said first and second side edges thereof, said first portion being tapered such that a distance from said first side edge to said second side edge of said first portion proximate to said forward end of said blade portion is less than a distance from said first side edge to said second side edge of said first portion proximate to said second portion, a distance from said first side edge to said second side edge of said first portion proximate to said second portion being less than a distance from said first side edge to said second side edge of said second portion, and said second portion not having grooves formed therein along said first and second side edges thereof.
25. A spade bit as defined in claim 24 , wherein said grooves formed in said first and second side edges of said first portion are straight grooves which are formed at a lead angle of approximately between four and eight degrees.
26. A spade bit as defined in claim 24 , wherein said first and second side edges of said second portion are formed as cutting edges.
27. A spade bit as defined in claim 24 , wherein a cutting surface is provided between said spur and said blade portion.
28. A spade bit comprising:
a shaft having a forward end and a rear end, said rear end of said shaft being configured to be received and held by a tool;
a spur having a forward end and a rear end, said forward end of said spur generally forming a point; and
a blade portion having,
a forward end and a rear end, said forward end of said blade portion being joined with said rear end of said spur, said rear end of said blade portion being joined with said forward end of said shaft,
first and second spaced-apart surfaces, said first and second surfaces being generally parallel, said first and second surfaces being spaced apart by a predetermined thickness of approximately between 0.085 and 0.095 inches,
first and second side edges which extend from said forward end of said blade portion to said rear end of said blade portion, and
first, second and third portions, said first portion extending from said forward end of said blade portion to said second portion of said blade portion, said second portion extending from said first portion of said blade portion to said third portion of said blade portion, said third portion of said blade portion extending from said second portion of said blade portion to said rear end of said blade portion, said second portion having grooves formed therein along said first and second side edges thereof, each of said grooves defining a pair of adjacent crests and a root therebetween, said first side edge of said first portion being positioned between said crest and said root of the groove of said second portion along said first side edge thereof which is most proximate to said first portion, said second side edge of said first portion being positioned between said crest and said root of the groove of said second portion along said second side edge thereof which is most proximate to said first portion, said second portion being tapered such that a distance from said first side edge to said second side edge of said second portion proximate to said first portion of said blade portion is less than a distance from said first side edge to said second side edge of said second portion proximate to said third portion, a distance from said first side edge to said second side edge of said second portion proximate to said third portion being less than a distance from said first side edge to said second side edge of said third portion.
29. A spade bit as defined in claim 28 , wherein said grooves formed in said first and second side edges of said second portion are straight grooves which are formed at a lead angle of approximately between four and eight degrees.
30. A spade bit as defined in claim 28 , wherein said first and second side edges of said third portion are formed as cutting edges.
31. A spade bit as defined in claim 28 , wherein a cutting surface is provided between said spur and said blade portion.
32. A spade bit comprising:
a blade portion having,
opposite first and second surfaces defining a predetermined thickness of approximately between 0.085 and 0.095 inches,
means for cutting a hole through a workpiece, said cutting means including a spur, and
means for pulling said blade portion through the hole of the workpiece said pulling means not being provided on said spur.
33. A spade bit as defined in claim 6 , wherein said rear portion does not have grooves formed therein along said first and second side edges.
34. A spade bit as defined in claim 16 , wherein said second portion does not have grooves formed therein along said first and second side edges.
35. A spade bit as defined in claim 20 , wherein said second portion does not have grooves formed therein along said first and second side edges.
36. A spade bit as defined in claim 28 , wherein said first portion does not have grooves formed therein along said first and second side edges.
37. A spade bit as defined in claim 28 , wherein said third portion does not have grooves formed therein along said first and second side edges.