Screw Points: A Guide to Their Versatile Functionality

Posted by Hugh Watson | March 4, 2016 3 Comments

A screw point is a small but essential tool available in a variety of forms and suitable for a range of applications. Useful for providing a transitional point between threads and points as well as ensuring proper hole alignment, screw points offer a plethora of simple but essential benefits.

A screw thread is a helical structure employed in order to convert between linear and rotational force and movement. Structurally, it consists of a ridge that is wrapped around a cylinder in a helical form. The screw thread is a pivotal feature of a screw as a fastener, as well as a simple machine in its own right.

A screw thread’s pitch is defined as the distance between two sequential thread crests. Optical comparators are the best tools to utilize when checking pitch.

When it comes to machine screws, there are two different types of measurable diameters — major and minor. The former is defined as the diameter that spans the crest of the thread, while the latter is the diameter that crosses the root of the thread. They are best checked with calipers and optical comparators, respectively.

Screw Points are available in a variety of forms and are applicable to a range of applications. They include:

Tapping Screw Types

  • Type A Point — A Type A point screw is employed for use with thin metal; it is utilized with drilled, nested, or punched holes in resin impregnated plywood, as well as sheet metal.
  • Type AB Point — This is a thread forming screw that fuses the locating point of Type A with the pitch and thread size of Type B.
  • Type B Point — Type B points are employed for use with heavier metal. It is equipped with a greater root diameter with a finer thread pitch.
  • Type BP Point — A Type BP point is almost exactly the same screw point as Type B, but is equipped with a cone point, to be used in places in which holes are misaligned.
  • Decking Screws — These are exterior screws used in applications such as arbors, decks, fences, and treated wood, as well as other applications that call for a high level of resistance to corrosion.
  • Decking Screws 17 — Type 17 screws allow a screw to penetrate into thick woods.
  • Particle Board Screws — Particle board screws are produced with asymmetrical threads equipped with the ability to resist pull out and slippage. Particle board screws offer exceptional holding power and quick assembly in many wood and particle board applications.

Thread Cutting Screws

  • Type F Point — A Type F point is a thread cutting screw with a machine screw thread that is equipped with a blunt tapered point. It is ideal for use with heavy gauge sheet metal, zinc, lead die castings, cast iron, and more.
  • Type 1 Point — Type 1 screws are equipped with a single flute made for general use. It creates a fine standard machine screw thread, used for field replacement.
  • Type 23 Point — This thread cutting screw provides maximum thread cutting area as well as exceptional chip clearing.
  • Type 25 Point — Similar to Type 23, Type 25 points are equipped with a coarse Type B thread.
  • Type 17 Point — This thread cutting screw is ideal for use with wood; it offers a coarse tapping screw thread as well as a special long sharp point that is fluted in order to capture chips.
  • Type BF Point — Type BF points are equipped with Type B threads and a blunt taper point.
  • Type G Point — Type G points are blunt die points with singular through slots used to form two cutting edges.

Thread Forming Screws

  • Tri-Round — This is a Type “TT” thread forming screw commonly used in coarse machine screw threads.
  • Type C Point — Type C point screws are equipped with a fine or coarse pitch machine screw thread as well as a blunt tapered point. They allow for replacement with standard screws in the field and eliminate chips.
  • Type CA Point — A Type CA point screw is equipped with a fine or coarse pitch machine screw thread. It offers a Gimlet point.
  • Type PT Thread Forming — This is a 48’ or 60’ thread option that lowers displacement of plastic, which decreases tendency to fracture bosses and reduces internal stress.
  • Type Hi-Lo Point — A hi-lo point is a dual lead screw commonly used in wood, plastic, nylon, and other low density materials. Its thread design improves upon drive to strip out torque, and decreases the risk of cracking the material.
  • Low Root — Low root thread is equipped with blunt points, and is ideal for use in plastic applications. There is a great deal of variations within this category of screws.

Self-Drilling and Self-Piercing Screws

  • Self-drilling — Self-drilling screws are equipped with drilling points that can drill through metal, plastic, and wood applications. Because it removes all hole preparation, self-drilling screws play an essential part in decreasing in-place fastener costs.
  • Self-piercing — Self-piercing screws provide for exceptionally stable sheet metal assemblies. These screws may be employed in order to drill through pre-punched holes in light gauge sheet metal.

Point Styles for Machine Screws and Tapping Screws

  • Header Point — A header point is one of the least costly pointing operations employed at the time of heading. It offers an end chamfer with a diameter smaller than the thread’s root.
  • Dog Point — A dog point is a straight pointed section decreased in diameter just slightly below the thread’s root diameter. Dog points help to ensure that fine threaded products are not stripped.
  • Rolled Point — A rolled point is an effective method of creating pointed long screws or studs equipped with an end chamfer similar to the die point.
  • Pinch Point (Rounded) — Pinch points are cost-efficient tools commonly utilized to assemble several parts that call for pilot action and aligning multiple sheets.
  • Nail Point (Pinched) — Nail points have a slightly squared surface and a sharp point, and are commonly employed for locking against wood and other soft material.
  • Cupped Point — A cupped point is comprised of a special cup section placed on the end of a threaded member, which will provide pressure without causing disfigurement.
  • Round Point — Round points consist of dome-like surfaces affixed to the end of a threaded piece, which offers pressure without resulting in disfigurement.
  • Cone Point — Cone points provide a smooth surface, a sharp point, and accurate length, which may be created to suit any desired contour needed to fit specific requirements.
  • Type U Drive Point — A Type U drive point is a thread forming screw offering a high helix thread useful for hammering into castings, sheet metal, plastics, or fiber for fast and efficient assemblies.

At Assembly Fasteners Inc., we offer consumers a wide selection of fasteners and different point types. For more information regarding our high quality products and the ways in which they can enhance your next project, please refer to our AFI Fastener Reference Guide here.