When would you use a combination of tolerance types on a single feature?

When would you use a combination of tolerance types on a single feature?

• A. When the feature must meet both a specific shape and a specific location relative to datums
• B. To specify only size
• C. When only location matters
• D. When tolerances are not required

Answer: (A)

In GD&T, you apply more than one tolerance type to a single feature when both its shape (form) and its position relative to datums are critical for the part to function. The form tolerance controls how the feature’s geometry deviates from its ideal shape, while the position (and other orientation/locational) tolerances control where the feature sits with respect to the datum reference frame. A common situation is a hole or bore that must be true round (or cylindrical) and also located precisely relative to datums. You’d use a form control such as circularity or cylindricity to guarantee the hole’s shape, and a true-position tolerance to constrain its axis’s location relative to the datums. Used together, these ensure the feature is both formed correctly and properly located for assembly. If only size mattered, you’d apply a size tolerance. If only location mattered, you’d apply a location tolerance without a form tolerance. If no tolerances were required, nothing would constrain the feature.

In GD&T, you apply more than one tolerance type to a single feature when both its shape (form) and its position relative to datums are critical for the part to function. The form tolerance controls how the feature’s geometry deviates from its ideal shape, while the position (and other orientation/locational) tolerances control where the feature sits with respect to the datum reference frame.

A common situation is a hole or bore that must be true round (or cylindrical) and also located precisely relative to datums. You’d use a form control such as circularity or cylindricity to guarantee the hole’s shape, and a true-position tolerance to constrain its axis’s location relative to the datums. Used together, these ensure the feature is both formed correctly and properly located for assembly.

If only size mattered, you’d apply a size tolerance. If only location mattered, you’d apply a location tolerance without a form tolerance. If no tolerances were required, nothing would constrain the feature.