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Zorluk: OrtaScrews

A technician is servicing marine hardware and needs to install a cross-recess screw that features sharp, 45∘45^\circ flutes meeting at a pointed apex rather than a blunt tip. Which type of screw drive is specifically designed with this geometry so that one screwdriver bit fits all standard screw sizes?

  1. A
    Phillips
  2. Frearson (Reed and Prince)Cevap
  3. C
    Torx
  4. D
    Robertson

Cevap

Frearson (Reed and Prince)
The Frearson (also known as Reed and Prince) screw drive features a four-point cruciform recess with sharp, true 45∘45^\circ flutes meeting at a sharp point. Because the angle is identical regardless of fastener diameter, a single Frearson screwdriver bit can drive all standard screw sizes while delivering high torque resistance without camming out.

Adım Adım Çözüm

1
Analyze the drive recess geometry described in the scenario
The screw features a cross-recess with sharp 45∘45^\circ flutes that form a pointed V-shape at the bottom rather than a blunt center.
Cruciform screw drives differ primarily in flute angle, corner radius, and center depth.
2
Match the identified mechanical characteristics to the appropriate drive standard
The Frearson (or Reed and Prince) design utilizes a true 45∘45^\circ angle across all sizes, enabling one standard bit to fit any Frearson fastener.
Unlike Phillips drives, which require separate driver sizes (#1 through #4) and have rounded corners designed to cam out, Frearson slots remain consistent in angle.

Anahtar Kavram

Cross-recess screw drive identification and geometry (Frearson vs. Phillips)

Alternatif Yöntem

Visually inspect the center of the cross: a sharp, deep point indicates a Frearson recess, whereas a blunt, rounded center indicates a Phillips recess.
Tahmini Süre:45s
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