Whether you’re an avid do-it-yourselfer or just want to make some quick home repairs, knowing how to properly tighten set screws is a good skill to have.
This guide will help you understand everything you need to know about set screws, the different types, the varying set screw drives, and how to tighten them effectively and accurately.
What Are Set Screws?
Set screws are a type of threaded fastener used to secure components in place. This often means affixing two or more loose parts to one another, most often using a wrench, and some kind of screw, which you install and securely fasten to ensure that quality furniture will stay set.
The pinning action of a set screw is a key difference when compared to a general-purpose screw.
They are used to create compression, which can hold two loose objects together firmly without using a nut or any other kind of socket or even a screwdriver or electric screwdrivers to keep everything together after assembly.
The intended purpose of a set screw is to fasten down parts that would otherwise slide and move relative to each other especially when there is torque applied.
It works by passing through a threaded hole in one component and positioning it against the surface of a second component on the rear side, and is used in conjunction with an fallen wrench.
The wrench bends the screw into place, using tightening torque.
Set screws are common in all variations of engineering, alongside other equipment, repair services, and product design to keep parts of an object locked into place.
Types of Set Screws
There are many different variations of set screws on the market that serve different functions and purposes. While most have a few key features in common, they have varying characteristics that are specific to certain uses and to a specific job.
1. Plain Cup
A cupped set screw has a slightly concave recess in the flat end of its tip, that allows you to link the screw to a particular key that twists it into place.
So, instead of the entire flat tip making even contact with the back component, all of the pressure is applied to the cup’s narrower circumference.
This design reduces the risk of damaging the screw shaft end by over-tightening while also providing good torque and locking force.
2. Flat
Flat point screws are made with a completely flattened end, which provides a more evenly distributed compression force when they make contact with a surface, which means that whatever it is used on will not eventually loosen from its socket and easily release.
These types of screws cause little damage to surfaces as the tip does not penetrate the surface significantly.
They are also reusable and can be removed without damaging them, and tightening them is incredibly easy, as you can set out on tightening them whenever you need.
3. Oval
Oval point set screws have a rounded tip that is slightly convex in shape. This design minimizes the risk of damage to a surface when components are locked in place.
Due to the screw’s smaller, rounded end, it is easier to make adjustments without having to completely remove or reset the screw, as movement against a fastened surface is made much easier so you can focus on the rotation of the screw in its socket, as you thread it through.
4. Knurled Cup
Knurled cup set screws are similar to plain cup set screws except that the outer edge features jagged teeth, also known as knurling.
The knurling on the screw is designed to latch onto the surface that the screw is positioned against to provide a stronger grip. They are often used in permanent assemblies as there is less risk of them coming loose over time.
5. Cone
Cone set screws feature a sharpened tip that is made to penetrate an underlying surface to a certain degree, allowing them to be tightened to a much stronger degree, and to allow the shorter end to plunge much lower into the surface.
The wedge effect that these screws have means that they provide a very strong grip along the shaft, much stronger than other types of set screws.
They are used exclusively in permanent fixtures as they are damaging to component surfaces especially at a certain angle.
6. Dog Point And Half-Dog Point
Dog-point and half-dog point set screws have a long, protruding tip that flattens out at the end. These extended ends are made to fit into a specific hole relative to its size, and the size of its shafts.
These screws are a middle ground between cone set screws and flat point set screws. They can also be removed and reused, but this is generally dependent on the permanence of the fixture they are being taken from.
7. Soft-Tipped
A soft-tipped set screw has a generally malleable end that is softer than the main body of the screw. The ends of these screws are often made from softer metals like brass, but can also be made from nylon, or a similar correct material that has a measure of strength to it.
The design of this screw allows the soft tip to morph against the surface material for a better locking grip on uneven planes, without looking crooked, or requiring you to unscrew them in order to have a room look just right.
8. Ball-Point
Ball-point set screws feature a ball tip at the end of the screw. These are less commonly used than other types of setscrew.
This type of setscrew is often used when two non-parallel surfaces need to be fixed together, allowing for easier affixing.
Types Of Set Screw Drives
1. Hex Socket And External Hex
The most popular drive type is typically the hex socket setscrew. This will most commonly be a drive socket that is internally recessed.
The head of the setscrew may occasionally have a more conventional projecting design that resembles a regular bolt, which can impact the overall quality of the job.
Hex set screws give the user a secure driving socket that is non-slip and deformation-resistant, allowing them to apply more torque while seating the set screw, no matter the diameter.
2. Square Socket and External Square
Square drive socket set screws come in both recessed and exposed forms, and save you from needing to use a screwdriver. Although it is typically regarded as less secure than a hex equivalent, the square-shaped drive also provides more torque and less slippage than a single slot version.
3. Bristol Spline
Bristol spline set screws have an array of four to six small teeth that project inward from the outside of the spline socket depression.
This configuration minimizes the possibility of stripping the socket drive under high torque by ensuring that all driving force is applied at a precise right angle to the fastener splines.
4. Straight Slot
A straight slot set screw is intended to be driven by a traditional drill bit or flathead screwdriver. It features a single recessed slot, much like general use screws.
How To Tighten Set Screws
When you have properly tightened a set screw, your components should lock into place firmly and not come loose.
Below are instructions on how to tighten a screw with an Allen key effectively. Don’t worry, you won’t need a screwdriver to drop the screw into place. For straight slot set screws, you can use a flathead screwdriver or drill bit.
- Place the set screw into the drilled and tapped hole made in the component.
- Using the long end of an Allen key, begin by turning your screw clockwise into place.
- When the head of the screw has reached the surface, use the other end of the Allen key in a back and forth motion.
- Continue to turn it and back off alternately until the screw is fastened into place and hidden inside the component.
Frequently Asked Questions
How Tight Should A Set Screw Be?
In general, a set screw should be as tight as possible but should not be forced if there is no more give.
It should be tight enough so that the components hold together, but not so tight that the screw’s threads are damaged. Make sure not to go overboard when using tools like a screwdriver.
How Do You Adjust a Set Screw?
Some set screws are not designed to be removed or adjusted once they are set in place.
If you think you will have to make adjustments often, then opt for an adjustable screw type, such as an oval point set screw.
Final Word
With this guide, you should be able to tighten a set screw properly so that your components are firmly fixed into place.
Consider which type of set screw you need before you get to work on your project so you can make sure your fixture is as sturdy and effective as possible.general-purpose