Safety Alert 87 – Safe use of battery operated drills

27 August 2020


The apprentice was working on a mezzanine level in the hallway installing an isolator for a machine. He took a 25mm hole saw out of the drill (Milwaukee 18 volt 5ah battery operated drill) and tried to loosen the hole saw from the arbor. The hole saw was jammed on the arbour so the apprentice put the hole saw back into the drill to get a better grip, to do so he put the arbour shaft into the drill’s chuck and operated the drill to tighten the chuck.

His right hand was around the chuck holding it to tighten the drill tooth and his left hand was on the drill trigger. As he was tightening the drill chuck his protective glove got caught between the drill tooth and the hole saw arbour, which caused his right hand thumb to rapidly twist causing injury.

Root Cause

  • Inadequate training – insufficient on-the-job training on the safe use of a drill
  • Lack of knowledge – incorrect placement of his hand on the hole saw arbor

Contributing Factors

  • Failure to follow procedures – safe use of battery operated power drill
  • Improper placement – incorrect hand position to tighten hole saw


  • On the job training for the safe use of powered drills is to be delivered to ensure that they are used in a safe manner to avoid injuries

How to safely attach a hole saw:

  1. Disable your drill by unplugging it or removing the battery.
  2. Open the chuck far enough to insert the hole saw arbour shaft into the drill.
  3. Hold the saw by its base while you tighten the drill chuck manually, either by turning it with your hand or using a chuck key, depending on the drill.
  4. Tighten the chuck as much as you can to prevent it from opening while you’re using the saw.
  5. Rotate the chuck a few times by hand to make sure the saw is centred, when satisfied, plug in the drill or insert the battery and commence use.


For further information regarding this Safety Alert, please contact EGT on (08) 6241 6100 or talk to your Field Officer.

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