Questions: set screws are used for permanent mounting of components on shafts. The point bites into the shaft to create a high axial and torsional locking strength. A. Oval point B. Dog point C. Cone point D. Cup point

The answer is the fourth one (or D): Cup point.

Explanation for each option:

• A. Oval point: Oval point set screws have a rounded end and are typically used where frequent adjustments are needed. They do not provide the high axial and torsional locking strength described in the question.
• B. Dog point: Dog point set screws have a flat tip and are used for permanent location of one part to another. They are not designed to bite into the shaft for high locking strength.
• C. Cone point: Cone point set screws have a sharp, conical tip that can penetrate the surface of the shaft, providing good locking strength. However, they are more likely to damage the shaft surface.
• D. Cup point: Cup point set screws have a concave tip that bites into the shaft, providing high axial and torsional locking strength without causing excessive damage to the shaft. This makes them ideal for permanent mounting of components on shafts.

Summary: The correct answer is D: Cup point, as it best matches the description of providing high axial and torsional locking strength by biting into the shaft.