Fillet vs Round — Interior and Exterior Blends Is a fillet correctly defined as a rounded exterior blend between surfaces, or is a fillet specifically an interior concave blend while the exterior convex blend is called a round?

Introduction / Context:
Precise naming of blends is critical in design, machining, and inspection. The term fillet is often used loosely, but in drafting and manufacturing terminology it has a specific meaning. The stem claims that a fillet is a rounded exterior blend. That is not correct. Fillet refers to an interior concave blend between intersecting surfaces. The matching exterior convex blend is a round. Correct use of these terms avoids miscommunication when specifying radii and surface transitions.

Given Data / Assumptions:

• Two surfaces meet either internally or externally.
• Blending replaces a sharp corner with a radius to reduce stress and improve flow or safety.
• Drawings must call out radius values and tolerances.

Concept / Approach:
Interior corner: use a fillet. Exterior corner: use a round. This convention is widely taught and supported by drafting standards and CAD tools. The rationale is clarity: different machining or molding operations may create interior versus exterior blends, and inspection points differ accordingly.

Step-by-Step Solution:
1) Determine whether the corner is inside (concave) or outside (convex).2) If inside, specify a fillet with its radius value; if outside, specify a round with its radius.3) Ensure that fillets at boss bases and pocket bottoms are sized to reduce stress concentration.4) Verify clearance for mating parts when rounds are applied to external edges.

Verification / Alternative check:
CAD commands and CAM toolpaths typically label features as fillet for interior edges and round for exterior edges, reflecting shop floor practice.

Why Other Options Are Wrong:
Correct repeats the incorrect definition. Partially correct or Context-dependent suggests ambiguity where the standard usage is precise. Not enough information does not apply because interior versus exterior is clearly stated.

Common Pitfalls:
Using fillet generically for all radiused corners; forgetting that large rounds may interfere with assemblies or reduce sealing land width.

Final Answer:
Incorrect