Self Tapping Screws
WHAT ARE SELF TAPPING SCREWS?
A self tapping screw is a screw that creates threads in the material that it is being fastened, unlike its machine screw counterpart. Self tapping is not a reference the tip of the screw but how the threads are designed to mate with the materials being joined.
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Diffrence between pointed self tapping & self drilling screws
Pointed self tapping screws
Featuring a pointed tip that can penetrate and fasten a wide range of materials including, sheet metal, wood, plastic, and drywall. For thick guage materials, a pilot hole is generally required
Self drilling screws
Some self tapping screws are also self drilling, providing a drill-like fluted tip that looks much like the tip of a center drill. Self Drilling Screws save on installation time and effort by drilling, tapping, and fastening materials in a single operation.
SCREW SIZE CHART
Sheet Metal Screw Size Conversion Chart
| Screw Size | Closest Fraction | Decimal |
|---|---|---|
| #0 | 1/16" | 0.060" |
| #1 | 5/64" | 0.73" |
| #2 | 3/32" | 0.086" |
| #3 | 7/64" | 0.099" |
| #4 | 7/64" | 0.112" |
| #5 | 1/8" | 0.182" |
| #6 | 9/64" | 0.138" |
| #7 | 5/32" | 0.151" |
| #8 | 5/32" | 0.164" |
| #9 | 11/64" | 0.177" |
| #10 | 3/16" | 0.190" |
| #12 | 7/32" | 0.216" |
| #14 | 1/4" | 0.242" |
PILOT HOLE SIZES
Sheet Metal Screw Pilot Hole Sizes
| Screw Size | Drill Size | Hole Diameter |
|---|---|---|
| #2 | No. 49 Drill Bit | 0.720" |
| #4 | No. 41 Drill Bit | 0.960" |
| #6 | No. 32 Drill Bit | 0.116" |
| #8 | No. 29 Drill Bit | 0.138" |
| #10 | No. 21 Drill Bit | 0.159" |
| #12 | No. 14 Drill Bit | 0.182" |
| #14 | No. 4 Drill Bit | 0.211" |
Where Are Self-Tapping Screws Used Regularly?
Since these are such diverse and versatile fasteners, they find use in many different applications. Some of the many industries where you may encounter self-tapping screws or self-drilling screws include the following:
- Construction and Building - self-drilling screws are commonly used in the construction industry to assemble modular structures, install drywall, and more.
- Woodworking and Cabinetry - Self-tapping screws can be incredibly useful when making cabinets or doing other forms of woodworking since they make the assembly process less demanding by creating their own thread.
- Automotive - The automotive industry often uses self-tapping screws when it comes to installing parts or attaching paneling.
- Electronics and Electrical - Electrical installations frequently make use of self-tapping screws, especially those with round heads, to accomplish a firm attachment.
- Roofing and Siding - Self-tapping screws are a perfect way to attach roofing sheets and metal siding.
Types of Self-Tapping Screws
Whether you're looking for self-drilling screws or self-tapping screws, you'll discover more types than you'd initially think. Let's discuss some of the different types of self-tapping screws.
Tapping Style
It's worth noting that both self-tapping screws and self-drilling screws have a few different versions of thread creation. Specifically, you may encounter:
- Thread-forming screws - The unique thread design on thread-forming screws displaces the material around the screw rather than cutting or removing it. They have shallower threads, placed closer together, than thread-cutting screws.
- Thread-cutting screws - The threads on thread-cutting screws are sharp and distinct, allowing them to cut into the material and create distinct threads.
- Thread rolling screws - This type of screw has helical ridges that are perfectly spaced according to a geometric construct. Rather than cutting or displacing the material, it rolls the material away from the screws.
Head Styles
One of the most significant differences between different types of self-tapping screws, the head shape, can make a significant impact on the potential uses of these fasteners. Let's investigate some of the different types:
- Flat - As the name suggests, flat-head self-tapping screws have a flattened profile from above. They're ideal for projects where the screw head should be flush with the surface of the project, or not protrude at all. For this reason, we also call them countersunk screws, since it has the same effect as when you countersink the project to make room for the screw head.
- Hex Washer - Hexagonal, Hex head, or hex washer screws have a much larger head than most of the other types. The enlarged head, along with the security provided by the hex shape, allows you to apply much more torque while simultaneously reducing the potential for stripping the screws.
- Round - The surfaces are fully rounded on round-top self-tapping screws, giving them a more polished appearance. They're ideal for plumbing and electrical applications, as well as any other applications that require ready access to the screws.
- Oval - Oval head self-tapping screws are slightly wider than round-head screws, giving them more surface area. Because of the increased surface area, they have a larger area of engagement. Additionally, they're more appealing visually, making them ideal for applications requiring practicality and aesthetics.
- Pan - Pan-head self-tapping screws have a rounded surface, much like the round-head screws. However, they're slightly convex. They have a larger surface area, ensuring that the screwdriver has more space to engage with. This type of self-tapping screw is ideal for many applications since the enlarged surface area helps prevent slippage during installation.
- Truss - Truss-head self-tapping screws have an increased bearing surface due to their low-profile wide heads. This makes them ideal for applications requiring heavy-duty bearing, or for attaching metal to metal.
How to Install a Self-Tapping Screw
Installing a self-tapping screw doesn't have to be a complex endeavor; however, it can be daunting if you haven't done it before. Here's a step-by-step guide:
- Choose the Right Screw: Ensure that you have the appropriate size and thickness of self-tapping screw for your application.
- Marking and Positioning: Mark the precise location where you want to place the screws, ensuring that it is 100% aligned to the appropriate position. You can use either a pencil or a marker of some sort.
- Pilot Hole (Optional): Drill a pilot hole, if desired, ensuring that you adhere to the pilot hole guide provided above. A pre-drilled hole will be of little use to you if it's the wrong size. If you only have a screwdriver and your self-tapping screws, skip this step. Bear in mind that harder materials like metal or hardwood may split, even if you're using a self-tapping or drilling screw. In these cases, even a small pilot hole can be useful for ensuring correct alignment and helping to get the screw into position.
- Inserting the Screw: Place the tip of the screw into the pre-drilled hole, or place it on the marked position. Ensure that your drill driver or manual screwdriver is in a 90-degree position so that the screw is perfectly level. This will ensure that the screw goes in straight.
- Start Turning: Now, you're ready to start turning the screw. If you're using a manual screwdriver, simply apply consistent pressure while turning clockwise. If you're using a drill driver, apply gentle pressure and start the drill slowly. It's better to insert the screw slowly and get it straight than to apply excessive pressure straight away.
- Creating Threads: As the screw turns, it will create threads for itself within the material. Keep turning until the head of the screw is flush with the material.
- Checking Alignment: Once the screw is installed, check that the screw went in straight and is properly aligned with the material. Make any required adjustments.
- Tightening (if needed): If you find that the screw isn't as tight as you'd like, or didn't go in all the way, now is the time to tighten it further.
Repeat: If you're installing multiple screws, repeat the process for each one.