2.6 Drills & Accessories


Drills are used to bore holes, tighten and loosen fasteners, and, with some models and accessories, mix paint, mortar, and similar materials, and to chisel and chip mortar, concrete, and other dense or hard materials. The selection of the proper dill for a job requires knowledge of the material being worked, the types and models of drills and their purposes, and the accessories that are appropriate for the task. Tool makers offer all of the types of drills in corded models and the majority of them are also available in variable speed and battery powered models that offer greater portability and reduced tool weight with lighter weight DC brushless motor technology.

Basic Drill Parts Identification

Portable Drill Parts by Gwen Arkin & Clifford Rutherford is licensed under CC BY 4.0

Drill Safety

  1. Wear safety glasses when operating with portable electric drill.
  2. Disconnect the drill from the electrical supply when installing bits.
  3. Clamp stock so it will not move during the drilling operation.
  4. Before drilling, turn the drill on to see if the bit is centered and running true.
  5. Align the bit with the desired hole location before turning the drill on.
  6. Hold the drill firmly with both hands while drilling.
  7. When drilling deep holes with a twist drill, move the bit up and down several times while drilling to remove cuttings and reduce overheating in the bit.
  8. Do not allow the cord to become wrapped around the drill when working.
  9. If the electrical cord becomes frayed or starts to separate from the drill housing, repair it immediately!
  10. Remove the bit from the drill as soon as the work is completed.
  11. Select the correct bit for the finish and material being drilled. Make sure the bit is securely tightened in the drill chuck.
  12. Be extremely careful when using larger portable electric drills (3/8″ and 1/2″). If the bit should hang or get caught the drill will twist in the operator’s hands causing a sprain or bruised fingers.
  13. Always remove the key from the chuck before drilling.
  14. To prevent seizing, reduce the feed pressure when the drill bit is about to come through the material.

Drill Operating Procedures

  1. Always center punch or make a starting indentation in the material being drilled to get an accurate starting point for the drill bit.
  2. Tighten the drill bit by rotating the chuck key to all three holes in the chuck. This will help to keep the drill bit centered.
  3. Apply moderate even pressure to the drill during the drilling operation. If excessive pressure is required to make the bit cut then the bit is dull and needs to be sharpened.
  4. Maintain good balance at all times when drilling.
  5. Use slow drill speeds for drilling metal and fast speeds for drilling wood.
  6. To obtain holes that are placed accurately, drill a small pilot first then drill the final hole.

Drill Types

Bits & Accessories

Along with using the driver bits for various fasteners discussed in the previous chapter, drills can be accessorized to perform a variety of functions.


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Building Maintenance & Construction: Tools and Maintenance Tasks (Interactive) Copyright © 2018 by University of Hawai’i Maui College and the Construction Technology Program is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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