Abstract: A low resistance anti-crack screw structure, including a low resistance screw comprising an upper section of screw, a middle section of screw, a lower section of screw, and a cone-shaped screw tail. The lower section of screw is recessed with at least one chip ditch that gradually becomes deeper from top to bottom. The chip ditch is tilted with respect to the central axis of the low resistance screw and has a chip removal angle between 10 degrees and 20 degrees. The second ditch section is inclined relative to the radial direction having an incline angle between 79 degrees and 89 degrees, and the maximum depth of the second ditch section is less than 55% of the radius of the lower section of screw. The lower side of the chip ditch is tapered close to the screw tail and has a drag reduction angle between 15 degrees and 20 degrees.

Abstract: A wooden screw may include a shank, a threaded segment, a screw head, a tapered portion and a stem portion. The shank diameter is smaller than the horizontal distance defined as a distance between two opposite ends of the tapered edges, while the width defined as a distance between two symmetric rear portions of blades is between the shank diameter and the horizontal distance, so a drill hole on the wooden material is not contacted with the shank during the screwing process, and the wooden screw also can reduce the friction and provide a complete mechanism for wood chips in accommodation and expulsion. Also, because the diameter of the drill hole is smaller than the horizontal distance, the tapered edges on the threaded segment are much easier to be screwed into wooden material. Therefore, the bonding strength between the wooden screw and the wooden material is increased.

Abstract: A wooden screw may include a shank, a threaded segment, a screw head, a tapered portion and a stem portion. The shank diameter is smaller than the horizontal distance defined as a distance between two opposite ends of the tapered edges, while the width defined as a distance between two symmetric rear portions of blades is between the shank diameter and the horizontal distance, so a drill hole on the wooden material is not contacted with the shank during the screwing process, and the wooden screw also can reduce the friction and provide a complete mechanism for wood chips in accommodation and expulsion. Also, because the diameter of the drill hole is smaller than the horizontal distance, the tapered edges on the threaded segment are much easier to be screwed into wooden material. Therefore, the bonding strength between the wooden screw and the wooden material is increased.