What Is a Starting Drill?
A starting drill is a tool used in machining operations before a regular drill is used.
It is also known as a “leading drill.” As the name “starting” implies, it is used for initial positioning and chamfering of holes. Starting drills are characterized by a shorter twist section and a 90-degree tip compared to regular drills.
This structural feature allows positioning and chamfering to be performed with a high degree of accuracy. In addition, the drill has a good bite when in use, making accurate positioning and chamfering quick and easy. Starting drills are one of the essential tools for machining accuracy.
Depending on the material, drilling holes with a regular drill may cause distortion, but starting drills enable accurate drilling with minimal distortion. Starting drills are also useful for positioning holes before drilling. Accurate positioning improves the accuracy of the drilling operation.
Uses of Starting Drills
Starting drills are primarily used for positioning operations in drilling. By drilling a hole just large enough to accommodate the chisel edge of a normal drill, it is possible to suppress the shake of the material and drill during drilling. This improves machining accuracy.
Starting drills can also be used for a machining operation called V-grooving, in which a V-shaped groove is drilled using a starting drill to determine the approximate location of the area to be machined. Starting drills play a very important role in making V-shaped grooves.
In addition to drilling, starting drills are also useful in other machining operations, such as deforming and centering. In deformations, the starting drill is used to determine the location of the workpiece before drilling, and in centering operations, the starting drill can be used to find the center location of the workpiece to be machined.
Principle of Starting Drills
Starting drills are specialized for drilling positioning holes and can drill holes with high accuracy. The chisel edge is short and rigid, making it easy to drill holes even in smooth materials, and it can also be used for chamfering after drilling.
The angle of the drill tip depends on the relationship between the normal drill size and the size of the hole. If the hole is larger, the center of the drill is more likely to shake, but this can avoid drill wear when drilling. Conversely, if the hole is smaller, the blurring will be smaller, but the drill body will be more prone to wear.
Another product that has a similar structure to starting drills is called a center drill. The center drill can be used for other purposes besides positioning, but the risk of damage during machining is relatively high due to its relatively thin tip.
Starting drills have a 90-degree tip and a short chisel edge for accurate positioning and chamfering. It is an indispensable tool when high precision is required in drilling operations. By adjusting the angle according to the smoothness of the work material and the size of the drill, higher machining accuracy can be achieved.
Types of Starting Drills
There are three main types of starting drills: HSS starting drills, cobalt starting drills, and tipped starting drills.
1. HSS Starting Drill
HSS starting drills are starting drills for general steel materials and are durable and suitable for a wide range of applications. They are used for general metalworking, including steel, and provide high accuracy in drilling.
2. Cobalt Starting Drill
Cobalt starting drills are more durable and heat resistant than HSS starting drills, making them suitable for machining hard materials and in high-temperature environments. They are also used for machining materials other than steel.
3. Starting Drill With a Tip
Starting drills with tips can be fitted with replaceable tips at the end of the drill, which can be easily replaced when the sharpness becomes dull. They can be used for a wide variety of materials and provide high accuracy in drilling.