Frequently Asked Questions (FAQs)
1. What is the difference between a spotting drill and a center drill?
Spotting drills and center drills have different purposes and advantages. Spot drills are more accurate and prevent secondary drilling cycles from wandering. Center drills, on the other hand, are used to drill support holes in the workpiece for a lathe center and create a starting point for a larger diameter hole.
2. What size spotting drill to use?
The ideal spot drill diameter should be around 70% of the ultimate drill diameter. Additionally, the point angle of the spot drill should be different from the point angle of the final drill. It is not recommended to use spot drilling in hardened steel.
3. How deep should you spot drill?
To calculate the depth of a hole to be spot-drilled, divide the diameter of the spot-drilled hole. For example, if you have drilled a 0.25" diameter hole and want a 0.031" chamfer, the diameter to be spot drilled will be 0.312". Spot drills typically have a 90-degree point angle.
4. Is spot drilling necessary?
Spot drilling is necessary to ensure accurate hole location. The short and rigid nature of spot drills minimizes deflection during the drilling process. However, if you are using a carbide drill or a screw machine length drill, spot drilling is usually not required.
5. What does a spot drill look like?
Spot drills differ from center drills in two key ways. Spot drills are thinner and lack the conical tips of center drills. Their accuracy in drilling a precise starting point is also superior. In general, spot drills have a more specialized design for accurate hole placement.
6. What are the different types of spot drills?
There are various types of spot drills available, including KEO Spotting Drill- Narrow Chisel, MICRO 100 QCS Solid Carbide Quick Change Countersink & Chamfer Tools, MICRO 100 CS Solid Carbide Double Ended Countersink & Chamfer Tools, and KEO Spotting Drills- Metric- Long 90° and 120° Pt Angle Cobalt.
7. Do carbide drills need spot drilling?
Carbide drills or insertable drills are more rigid than HSS tools and generally do not deflect, eliminating the need for spot drilling. In fact, some manufacturers recommend against using a spotting drill with carbide drills or inserts to avoid chipping.