Spot Drill—The First Step in Precision Drilling
In precision drilling, the drill bit may wander and slip, resulting in unsatisfactory results. This can lead to hole deviation, insufficient accuracy, and poor hole wall quality.
After extensive testing, it was found that pre-damaging the workpiece surface before formal drilling can greatly improve drilling stability. Spot drilling has become the best tool for pre-processing.
What is a Spot drill?
A spot drill, also known as a CNC spotting drill, is primarily used to pre-machine precise, shallow indentations or guide holes on workpieces prior to drilling.
This indentation serves as the starting point for subsequent precision drilling, ensuring that the main drill bit follows the predetermined path accurately without drifting or deviating.
Specifications of spot drill
Drill tip angle: Common drill tip angles include 90 degrees for general positioning and 120 degrees for harder materials.
Shank type: Typically straight shank.
Overall length: Center drills are solely used for hole centering, so they do not need to be excessively long. Shorter drills offer higher rigidity and precision.
Coating: Select the appropriate coating based on the material being processed.
What is the purpose of a spot drill?
The purpose of a spot drill is to create a small hole when starting to drill, ensuring the drill bit is centered correctly. Additionally, in practical use, it can also chamfer the hole opening. By leaving a chamfer, the screw will be flush with the part after insertion.
How to select a spot drill bit?
Ideally, the center of the carbide drill bit should be the first part to contact the workpiece. Therefore, the drill point angle of the center drill should be greater than or equal to the drill bit’s point angle. If the drill point angle is too small, it may cause wear on the main drill bit’s cutting edge, reducing the drill bit’s service life. The following is a diagram of the drill point angle.
Correct angle Acceptable angle Incorrect angle
In drilling operations, a larger drill tip angle results in faster processing speeds and is typically used for soft metals such as aluminum and copper.
A smaller drill tip angle is more suitable for processing hard materials such as steel, as it provides greater engagement force. At the same time, a smaller drill tip angle experiences less wear and tear and is more uniform, but it is more prone to cutting.
Therefore, it is important to select a suitable spot drill that matches the main drill bit for pre-processing.
Need custom carbide drill bits?
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