Question 7 of 7: Case Study — Drill-Press Operator's Glove Caught in Revolving Drill During Tool Change

Question 7: Case Study — Drill-Press Operator's Glove Caught in Revolving Drill During Tool Change (20 marks: 6/7/7)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

(i) Cause of the Accident

Direct cause: the operator's glove caught on the still-revolving drill bit/chuck while she attempted a tool change with the machine running at slow speed rather than stopped, and the resulting entanglement pulled her hand into the rotating spindle, amputating the middle finger.

Contributing/root causes:

• Gloves worn while operating rotating machinery — a fundamentally incompatible combination: a glove that would protect the hand from a sharp-edged fastener during handling becomes an entanglement risk the instant it contacts a rotating spindle or bit, because the glove's fabric can catch and wind in where bare skin would simply slip.
• Tool change attempted without stopping the machine — the task ("make a tool change") requires direct hand contact at or near the chuck, which is only safe with the spindle fully stopped and, ideally, locked out; performing it "at a slow speed" treats a reduced RPM as equivalent to stopped, which it is not — a slow-turning spindle can still catch and wind in a loose glove just as effectively as a fast one.
• No engineering control preventing hand access to a rotating spindle — no spindle guard, interlock, or spindle-lock requirement that would have made the tool change physically impossible without first stopping the machine.
• Inadequate procedure/training on the tool-change task — no enforced safe-work procedure requiring "power off, spindle fully stopped" before any hand contact with the chuck area, and no job safety analysis had evidently flagged glove-plus-rotating-spindle contact as the specific hazard combination it is.
• Likely production-pressure influence — changing tools "at a slow speed" rather than stopping suggests an implicit expectation of minimizing cycle interruption, a common latent organizational pressure behind exactly this kind of shortcut.

(ii) Corrective Actions Required

• Mandatory stop-and-lock before any tool change — revise the standard operating procedure to require the spindle be brought to a complete stop (and, where the drill press has the capability, mechanically locked) before any hand contact with the chuck or bit, eliminating "slow speed" as an acceptable in-between state.
• Prohibit gloves at the point of operation — establish and post a rule that gloves are removed before any tool-change or chuck-area contact task on rotating-spindle equipment (administrative/PPE-selection correction); where handling sharp fastener edges is a genuine hazard elsewhere in the task, use cut-resistant handling methods that do not create the same entanglement risk at the spindle.
• Install an engineering control that removes the option — a spindle guard or interlock that must be retracted (which itself stops or prevents spindle rotation) before the chuck can be accessed, so the safe sequence is enforced by the equipment rather than relying solely on the operator's judgement.
• Retrain every drill-press operator on the corrected tool-change procedure, specifically addressing why "slow speed" is not a safe substitute for "stopped," and why gloves must never be worn near a rotating chuck.
• Conduct a job safety analysis (JSA) for the tool-change task on every drill press in the facility, explicitly identifying glove/rotating-spindle entanglement as a hazard and documenting the required control sequence.

(iii) Follow-Up Action Required

• Regulatory incident reporting — report the amputation to the applicable provincial OHS regulator within the mandated timeframe (a critical/lost-time injury of this severity is reportable), and to the Workers' Compensation Board.
• Formal incident investigation and documentation — complete and retain a documented investigation using the root-cause approach from part (i), forming the basis for the corrective actions in part (ii).
• Extend the corrective actions plant-wide — audit every other drill press (and any other rotating-spindle machine tool) for the same missing guard/interlock and the same glove-use practice, rather than treating this as a single-workstation fix, since the underlying unsafe condition is a task type, not one machine.
• Verify and audit implementation — confirm the guard/interlock is actually installed and functioning, the revised procedure is trained on and followed, and schedule a follow-up audit (e.g. at 30/90 days) to confirm the correction has not quietly lapsed once production resumes.
• Review through the joint health and safety committee — present findings and corrective actions to the workplace health and safety committee to close the loop with worker representatives.
• Update the injured worker's return-to-work and accommodation plan, coordinated with the compensation board, reflecting the permanent partial disability from the amputation.
• Feed the incident into ongoing training as a case example for future machine-tool and glove-use training, closing the loop from a real event back into prevention.