CentreDrill

Spot drills, commonly known as NC spot drills, are mainly used to drill an accurately positioned indention on a workpiece surface. The indentation acts as a guide and a reference point for non-self-centring drills. Using a spot drill will improve the overall accuracy of the finished hole. The design and substrate of NC spot drills vary, however typically feature a 90°, 120° or 142° drill point angle and are manufactured from HSS or carbide.

When choosing a spot drill, it is important to select the correct drill point angle. This is key to achieving and maintaining the highest accuracy. The chosen point angle determines the contact area and depth of the initial indentation or spot, also serving as a precise reference point for the drilling operation. Using the correct point angle ensures that the centre of the drill bit makes the first contact with the workpiece, reducing the risk of chipping the cutting edge and eliminates risk of deviations and improve overall precision.

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Spot drillvs centerdrill

Disclaimer This data is provided for general information only. The intention is to provide accurate information; regardless; errors may exist in the supplied information. If accuracy is critical, base your final decisions on the data provided in the root document: ISO 228; which is a copyrighted document. To purchase a copy visit an Authorized Reseller.

CenterDrill bit

NC spot drills can be used on various materials, with the exact material-set dependent on the spot drill substrate and coating. HSS (high speed steel) spot drills can be used on mild steel, alloy steel, tool steel, cast iron, non-ferrous metals and plastics. It's important to note that while HSS is a versatile material, it may not be the best choice for extremely hard or abrasive materials. Carbide spot drills are better suited to drilling difficult to cut metals like stainless steel, titanium, steel up to 50 Rockwell and abrasive non-ferrous metals. Having a coating on the spot drill will improve tool life and help protect against heat build-up, whereas uncoated spot drills are better suited to drilling plastics and sticky materials like aluminium. Not having a coating prevents material build up on the cutting edge.

Comments: Original Posting: 2/28/2008 Last Revision: 2/12/2013 Error corrections in, or comments about, the above data can be sent to: office@gagecrib.com

Like many cutting tools, spot drills are available in HSS (high speed steel) and carbide, both having different benefits:

When selecting a spot drill for your application, it's important to consider several key factors to ensure optimal performance: