Bottoming tap and chaser and method of use
View Patent ↗A tap and chaser are provided each having a cylindrical tool receiver connected to a threading section by a shaft. The receiver and shaft are of diameters sufficiently small to enter the bore hole and distribute any off axis load onto a number of internal threads of the bore hole to dissipate loading. The threaded section includes a group of longitudinal flutes. Each of the lands of the threaded section includes a novel cutting face, tooth angle and rake angle to advantageously allow for threading deep blind holes.
1. A tap comprising:
a receiver, with a first diameter, having a drive socket, a longitudinal axis and a radial axis;
a shaft section, with a second diameter, connected to the receiver, coaxial with the longitudinal axis;
a threading section, connected to the shaft section, coaxial with the longitudinal axis;
the threading section further comprising a set of longitudinal flutes with each longitudinal flute of the set of longitudinal flutes, forming a helix angle with the radial axis;
the threading section further comprising a set of threads having a crest diameter and a root diameter;
wherein the root diameter is greater than the first diameter and the second diameter; and
wherein the receiver has a first length, the shaft section has a second length and the threading section has a third length;
wherein a ratio of the first length to the second length to the third length is between 1:2:1±10% and 1:0.5:1±10%.
2. The tap of claim 1 , wherein the threading section further comprises:
a land, having a cutting face, perpendicular to the longitudinal axis; and,
wherein the cutting face has a hook angle of between 0°±0.3° and 15°±0.3°.
3. The tap of claim 2 , wherein the hook angle is between 3° ±0.3° and 5°±0.3°.
4. The tap of claim 2 , wherein the land further comprises a rake surface at a reduced rake angle.
5. The tap of claim 4 , wherein the reduced rake angle is between 0°±2° and 15°±2°.
6. The tap of claim 4 , wherein the reduced rake angle is between 2°±2° and 8°±2°.
7. The tap of claim 1 , wherein the set of longitudinal flutes further comprises:
a set of three equally spaced longitudinal flutes at a 90°±2° helix angle from the radial axis.
8. The tap of claim 1 , wherein the drive socket has a spanner cross-section.
9. The tap of claim 1 , wherein the receiver has a first circular cross-section and the shaft section has a second circular cross-section.
10. The tap of claim 1 , wherein the receiver, the shaft section and the threading section are oil quenched.
11. The tap of claim 1 , wherein the set of longitudinal flutes further comprises three spiral flutes at a 120°±2° flute distribution angle.
12. The tap of claim 1 , wherein the threading section is blunt ended.
13. The tap of claim 1 , wherein the first diameter is larger than the second diameter.
14. The tap of claim 1 , wherein the receiver, the shaft section and the threading section are carbon steel.
15. The tap of claim 1 , wherein the receiver, the shaft section and the threading section are cylindrical.
16. The tap of claim 1 , wherein the first diameter is between 2%±5% and 20%±5% less than the root diameter.
17. The tap of claim 1 , wherein the threading section further comprises:
the set of threads includes at least a top thread and a bottom thread; and
the top thread directly connected to and engaging the shaft section, coaxial with the longitudinal axis;
wherein the second diameter is constant from the top thread to the receiver.