Counter sinking: don't forget this step
The day has been long, it's getting dark outside, your stomach is growling, your arms are tired, and the project is still not completed. No matter how much passion you have for craftsmanship, there are situations when you just want to finish. That's when the question may cross your mind: Is this one small step really that important, or can I skip it just this once?
Countersinking is a candidate for exactly that question. Countersinking usually doesn't directly contribute to the success of a project and may seem dispensable at first glance. But appearances can be deceiving! Even if a borehole doesn't require countersinking, it doesn't mean you can achieve the same professional results without this technique. Moreover, countersinking with the right tools is not that difficult. Let's take a closer look at what makes countersinking special and what you need to keep in mind.
Why Countersinking Is Important
Countersinking is one of the material-removing processes. It differs from drilling because it doesn't work into solid material. Instead, the process can only be performed on an existing borehole. Material is removed from the edge of a borehole, creating a conical depression with various angles.
Conical sinking is applied for three main reasons:
Countersinking for Deburring
When drilling into metal, you can get burrs at the edge of the borehole. These are material fibers or splinters that are still firmly attached to the workpiece. Burrs are foreign objects that can cause significant problems, leading to parts not fitting or functioning as desired. Due to their sharp edges, they also pose a safety hazard and leave an unclean appearance. Countersinking is a simple way to completely remove burrs and create a smooth surface at the edge of the borehole.
Countersinking for Tapping
Countersinking is a popular technique, especially for tapping, as it makes it easier to start with the screw tap. Counter sinking increases the diameter at the entrance of the borehole. This requires less precision when starting with the screw tap. Essentially, countersinking creates a kind of funnel, making it easier to place the tapping tool correctly.
Countersinking Screws for a Clean Finish
Countersinking is also excellent for sinking screws. The head of a screw is larger than its body and, as a result, cannot completely disappear into the thread, which often wouldn't be practical. However, to ensure that the screw head doesn't protrude from the flat surface of a workpiece and cause interference, you can create space through countersinking. This allows you to sink the screw into the material without causing any disruptions. Additionally, countersinking provides an aesthetically pleasing finish.
Tools You Need for Countersinking
To perform countersinking, you need specialized tools called countersinks. These are tools with a conical head and multiple cutting edges. When countersinking, you can choose from various angles of depression created with the tool. To prepare for tapping and to sink screws, a 90° angle is commonly used. However, this applies only to countersinking metric screws. For countersinking screws following US standards, an 82° angle is needed. Countersinking to deburr can also be done at 60° angles. Other angles are used for countersinking rivet heads (75°) or sheet metal rivets (120°).
Additionally, there are specialized tools for countersinking. Guide pins, for example, ensure that the depression is centered with the borehole. A cross-hole countersink has a hole in its head with cutting edges at its edge to remove chips and prevent chip problems during countersinking, leaving a high surface quality. For the demanding task of deburring holes in pipes, a pipe deburrer is used. Due to its sophisticated geometry, it can countersink the cutting edges of such a borehole from both the inside and the outside simultaneously.
How to Succeed in Countersinking
Before you begin countersinking, you must always drill a pilot hole in advance. Start by using a twist drill bit of the appropriate size and design to create such a borehole. Now you need to choose the right tool to perform countersinking. A countersink must match the size and angle of the screw head you want to sink. Sets with various tools in different dimensions are particularly convenient.
Once you have found the suitable tool, you can start countersinking. The depth to which you penetrate the material depends on the purpose of the countersinking. To deburr the edge of the borehole, a few millimeters are sufficient — or until the burrs are completely removed. However, if you want to sink a screw, you should countersink the cone until it has fully entered the borehole with its full diameter. Only then can the screw head be sunk. Finished! Now you can tap the thread and sink your screw, leaving you with a flat, clean, and burr-free surface.
Convinced that countersinking is a step you shouldn't neglect? We have something for you! In the BAER online shop, high-quality countersinks made of high-speed steel are waiting for you, making countersinking effortless. With bit-shaft tools from us as your screw tap manufacturer , countersinking can even be done with a cordless screwdriver. If you need more information or have any questions, feel free to contact our customer service. We are here for you at all times!