CFS CFS Fastener Head Styles & Drive Types

Question 1

Which head style provides the largest bearing surface and is commonly used in wood and soft material applications?

Accepted Answer

Truss head

Answer

Truss heads have an extra-wide, low-profile design that distributes load over a larger bearing area, making them ideal for soft or thin materials.

Question 2

A Torx (star) drive fastener is designated by the letter 'T' followed by a number. What does the number represent?

Accepted Answer

A size code corresponding to the drive tool tip dimensions

Answer

The number following 'T' in a Torx designation (e.g., T25) is a size code that specifies the dimensional geometry of the drive tool tip, not a direct measurement.

Question 3

Which drive type is specifically designed to provide a 'cam-out' effect to prevent overtightening on assembly lines?

Accepted Answer

Phillips

Answer

The Phillips drive was engineered with angled flanks that cause the driver to cam out when a set torque threshold is reached, limiting overtightening in production environments.

Question 4

What distinguishes an oval (raised countersunk) head from a flat (countersunk) head?

Accepted Answer

Oval heads have a slightly domed top surface above the countersink bearing surface

Answer

An oval head has the same conical countersink bearing surface as a flat head but features a slightly rounded dome above the surface for a decorative or finished appearance.

Question 5

Which head style is most appropriate when a fastener must be flush with or below the work surface in a countersunk hole?

Accepted Answer

Flat (countersunk) head

Answer

Flat (countersunk) heads are designed with a conical bearing surface that seats into a matching countersunk hole, allowing the fastener to sit flush or below the material surface.

(CFS) Certified Fastener Specialist Practice Test

(CFS) Certified Fastener Specialist Practice Test

CFS CFS Fastener Head Styles & Drive Types