About TEK Screws

The following information is complied compliments of All Points Fasteners, Totally Nuts And Bolts, and Fastenermart
Tek® screws, which are self-tapping fasteners, have a very small carving at the end of its tip called a drill bit. This particular product is very popular since it is basically a self drilling  product cutting back on the number of steps necessary to complete projects by eliminating the need to pre-drill.hese screws are meant for metal to metal applications only with the exception of the reamer Tek® screw which is designed exclusively for a WOOD to METAL application.
Standard self-drilling tek® screws were never designed to go from metal to wood as the diameter of the hole that the drill bit will create will be close to the same diameter as the outside threads of the threaded portion of the fastener and will not allow the threads to tap into the wood to be secure. ​The exception to this are some self-drilling screws that are manufactured for roofing applications. The drill bit on those screws is very tiny, a #1 drill bit, and the diameter of the hole that the drill bit makes is substantially smaller than the diameter of the outside threads of the rest of the screw. This allows the threads to really bite into the material and allow the screws to self-tap into the metal or wood for a secure hold.​Contractors use Tek® screws  for screwing metal to metal and sometimes wood to metal. Depending on the thickness of the material you are drilling into, you have several drill points available, the longest being a Tek® 5, sometimes referred to as a ‘beambuster‘. These particular screws allow the user to fasten two pieces of material together without pre-drilling.
These screws come in varying sizes. In the case of hex head Tek® screws, check our our video to help you understand how to determine the size of screws based simply on the size of the hex head plus other additional information. Self-drilling screws, Tek® screws, are available in a variety of shank diameters and lengths as well as head styles.  Depending upon the type of work you are using them will dictate which type you need to complete your project.
 
Two of the most common types of head syles on Tek® screws that you will find on the market are the hex washer head and modified truss. Flathead screws are used when you need a flush surface. The hex drive is the preferred drive of most contractors doing heavy duty metal installations. Other than that, all other styles of heads on self-drilling screws generally have a Phillips drive although square drive is becoming more and more desired. Reamer tek® screws, self-drilling screws with wings, are the ultimate wood to metal screws.
 
Stainless steel self-drilling screws:  They are available but the tips are not  really the best for drilling into stainless steel. For this application, bi-metal tek® screws are suggested, where the body of the screw is stainless but the tip is made of carbon steel which allows the screw to drill into the stainless.

 

 

Standard Fasteners

 

Application

Use

Dia.


Material
Thickness

Point Length
Inches | Decimal

 

 

 

Light
Gauge
Metals

Teks / 2
tek_stand_2.jpg - 5874 Bytes

 

No. 4

.035 To .080

9/16

.140

No. 6

.035 To .090

9/64

.140

No. 8

.035 To .100

5/32

.156

No. 10

.035 To .110

13/64

.203

No. 12

.035 To .140

15/64

.234

1/4″

.035 To .175

19/64

.296

 

Medium
Gauge
Metals

Teks / 3
tek_stand_3.jpg - 4944 Bytes

 

No. 8

.100 To .140

13/64

.203

No. 10

.110 To .175

1/4

.250

No. 12

.110 To .210

9/32

.281

1/4″

.110 To .250

5/16

.312

 

Heavier
Gauge
Metals

Teks / 4
tek_stand_4.jpg - 4826 Bytes

 

No. 12

.175 To .210

9/32

.281

1/4″

.175 To .250

5/16

.312

 

Heavier
Gauge
Metals

Special Teks / 2
tek_stand_s4.jpg - 5411 Bytes

 

No. 12

.210 To .345

7/16

.437

1/4″

.250 To .375

15/32

.468

 

Heavier
Gauge
Metals

Teks
tek_stand_drillit.jpg - 4663 Bytes

 

 

 

Special Purpose Fasteners

 

 

 

Application

Use

Diameter

Recommended
Material
Thickness
Cold Rolled
Steel

Sheet
To
Sheet

Stitch Teks
tek_spec_stitch.jpg - 5342 Bytes

1/4″
5/16″

To 2
Sheets
of 24 Ga.

Plywood Or
Composite
(Over 1/2″ max)
To Metal

Plymetal Teks
tek_spec_plymetal.jpg - 5363 Bytes

No. 10

To .175
Max.

Plywood Or
Composite
(Over 1/2″)
To Metal

Plymetal Teks
with Wings
tek_spec_wings.jpg - 5911 Bytes

No. 10

.089 Min.
To
.175 Max.

Drywall
To Metal
Or Wood

Drywall Teks
tek_spec_drywall.jpg - 5911 Bytes

No. 6

No.8

Up To
26 Ga.

Gypsum To
Metal
Studding

Gypsum Teks
tek_spec_gypsum.jpg - 5911 Bytes

No. 6

.035
To
.090

2×4 Or
Firring
To Steel

tek_spec_header.jpg - 4213 Bytes

No. 12

No.14

.089 Min.
To
.210 Max

 

 

 

 

 

 

Self-drilling screws are available in the following material:

  • Zinc-Plated Steel – The most common and provides very good rust resistance.

  • Weather-Guard Coated (STALGARD®) – Helps protect ferrous metals from rust and corrosion better than many conventional finishes.

  • Stainless Steel – Both 18-8 and 410 are available. 18-8 provides excellent corrosion resistance. It can be mildly magnetic. 410 is stronger than 18-8 and is magnetic. It should be used in a chemical environment.

In addition, a special hybrid consisting of a hard steel driver fused at mid-body with an 18-8 head provides superior drilling and excellent corrosion resistance.

STYLES

  • Hex Washer Head – The built-in washer provides an excellent bearing surface. They can be slotted or unslotted, although unslotted is most common. The length is measured from under the head.
  • Pan Head – This low profile head can be a phillips or a square drive. The length is measured from under the head.
  • Flat Head – This countersunk head sinks into wood for a flush finish. The length is measured from the top of the head.
  • Oval Head – A countersunk base (like a flat head) but with an oval on top for a finished look. The length is measured from the top of the head.
  • Flat Head Reamer – A flat top and phillips drive ream wood and then cut steel in one operation. Wings ream clearance hole in thick layers of low density materials to prevent thread engaugement. When the point penetrates the metal underneath, the wings break off and the threads engauge normally. The length is measured from the top of the head.
  • Round Washer Head – These are similar to HWH but have a round head with a phillips drive. They are also known as Metal Lath or K-Lath or Modified
  • Truss Screws – The length is measured from under the head.
  • Wafer Head – Also know as plymetal because they can be used to attach plywood to metal. The large wafer head sinks into the plywood and has a large bearing surface. The length is measured from the top of the head.
  • Drywall Bugle Head – These will fasten drywall to metal studs (0.105″). The length is measured from the top of the head.
  • Pan Framing – A phillips drive stud-framing screw for attaching stud to track. The length is measured from under the head.
  • Pancake Head – A very low profile head with a large bearing surface. The length is measured from under the head.
  • Square Trim — A square drive and reduced head for tight spaces. The length is measured from under the head.

 

 

Tapping screws, especially Type A, are referred to as “sheet metal screws” because one of their first applications was in ventilation ducts made of sheet metal. Over time, though, different types evolved. We’ll cover the common groups: thread forming, thread cutting, thread rolling and self drilling. The combination of point and thread style determines to which group the screw belongs.

 

Types of Tapping Screws

In general, if the letter “B” is in a screw’s designation, such as Type AB or B, it has spaced threads. If the “B” is absent, as in Type F, the screw has machine screw threads. There are two exceptions: Although considered obsolete but still available today, Type A has spaced threads. And metallic drive screws, denoted Type U, have spaced spiral threads.

Hole size is important for all tapping screws except those capable of self drilling, which includes sharp point types. If the hole is too large, the screw will be loose, the hole could strip during assembly (you can’t properly tighten the screw), or the screw could pull out under tension. If the hole is too small, higher driving force will be required possibly causing the screw to break, or the material may crack or split. Consequently, it’s important to always drill or punch the correct size hole.

Thread forming screws have coarse threads and are designed to be used in thin gauge malleable material; a hole of the proper size is required. As the fastener is installed, the hole is enlarged by merely pushing the material outward. Consequently, burrs are common. Types A and AB, which have a standard point, and blunt point Type B, are common sheet metal screws; Types A and AB are usually considered interchangeable. Sizes typically range from #2 to 3/8.

If the metal is thicker—and harder—thread cutting screws are used. Cutting flutes at the tip of these screws act like a tap to create mating threads in the material as they are installed. Like taps, the correct size hole is required. And, also like taps, chips are created. If installed in a blind hole (the hole doesn’t go through the material), the chips will collect in the bottom of the hole so make sure there is sufficient depth. If the screw is inserted into a through-hole, the chips will be deposited on the exit side. Be careful that metal chips do not create electrical shorts, contaminate lubricants, or somehow inhibit mechanical operation. Type F is a very popular thread cutting screw. Because these screws are essentially machine screws, their threads are more closely spaced than sheet metal screws. After a hole has been tapped by a thread cutting screw, it can be replaced by a machine screw of the same size (diameter and number of threads per inch). Sizes of 4-40 to 3/8-16 are common.

Self drilling screws, also called Teks®, have a tip that resembles a drill, and often have spaced threads, like sheet metal screws. In a single time-saving operation, these screws drill, tap and fasten. Do not use self drilling screws in blind holes (holes that do not pass through the material). Also, the drill point must drill completely through the material before the first thread begins to thread into the material. That ensures proper fastening because the material will be fully engaged by threads. Drill chips are created that affect electrical and mechanical equipment. Four different point styles—#2, #3, #4 and #5—are available. Generally speaking, a #2 point is used with light gauge materials, #3 for medium gauge, and #4 and #5 points with heavy gauge materials.

Type U metallic drive screws have spaced spiral threads and a blunt point. These screws are forced under pressure into the material. Drive screws are considered permanent whereas other tapping screws can be easily removed.

If you are working with low-density materials like plastic, particle board, Masonite® and wood, consider using fasteners with High-Low threads. The “high” thread is quite sharp, while the “low” thread is more conventional and about 1/2 the height of the “high” thread. These screws are easier to install (less driving torque is needed), thread stripping is reduced, pull-out strength is increased, and there is less chance of splitting or cracking the material.

One final design that is very common is the drywall screw. Available in sharp point and self drilling styles, the sharp point is used with wood and light gauge steel studs, and the self drilling style is designed for heavy gauge steel studs. The unique bugle head is self countersinking, resists tearing the drywall paper surface and is said not to damage the gypsum core.

 

Nov 6, 2017   7591    Engineering Principles    
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