Incident Description

A student shop technician had a near miss incident while using the 12” sliding compound miter saw in a carpentry/ woodworking room. The technician was practicing straight cuts on a 3 & ¾” block of hardwood as part of their woodworking training when the workpiece bound to the blade and was thrown into the lower blade guard, fracturing both pieces and ejecting fragments into the room. The cause of the incident was determined to be improper setup, primarily due to the use of material that was too small for the miter saw. The technician was not injured.

What went right?

The student shop technician was equipped with all required PPE (safety glasses, closed toed shoes, long pants, and hearing protection) at the time of the incident. After the incident occurred, they immediately shut the machine down and reported it to full-time staff, who assessed them for injuries. Shortly after, the machine was locked and tagged out, and EH&S was contacted to determine the protocol for documenting and reporting the incident. 

Prior to the incident, the technician had been given a demonstration covering how to operate the machine/fixture workpieces safely and made multiple cuts under the supervision of full-time staff before being allowed to operate the machine on their own. The miter saw was appropriately guarded and maintained according to the manufacturer’s specifications, equipped with necessary parts and clamps, and in good working condition at the time of the incident.

There was an existing SOP (Standard Operating Procedure) for the miter saw.

What should have been done differently?

Because the workpiece was too short, the technician couldn't adequately secure the workpiece to the table using the fence clamps. Furthermore, the workpiece was not supported on both sides of the blade by the cut fence, which prevents the workpiece from being caught by the rotation of the blade. Instead, one side of the workpiece was positioned between the fences. As a result, when the saw started cutting, the workpiece shifted and bound to the blade, pulling it up into the retracted blade guard. This caused the guard and the workpiece to fracture and scatter outward into the room, including toward the user. It is possible to make cuts with the workpiece in contact with only one side of the cut fence, but only if it is securely clamped with the entire surface of the clamp. 

The user should not have attempted to cut a workpiece that was too small to be clamped sufficiently and supported by the fence on both sides of the blade. Although there is no written formal reporting protocol or response procedure the technician had to follow if unable to secure the workpiece, the technician was instructed during demonstration that if the fixturing felt unsafe or insufficient, they should stop immediately and consult a full-time staff member before proceeding.

How to prevent this in future:

Several steps can be taken to ensure near misses like this do not occur in the future.

1. Ensure effective communication between technicians and full-time staff, and there are issue reporting protocols in place. In particular, ensure that technicians understand they should communicate any uncertainties and have the authority to stop the task and request assistance.

2. Incorporate a hands-on quiz into machine training that tests users' judgment for safe fixturing. Potential users will be given workpieces of varying sizes and shapes and must determine if they can be safely fixtured and cut using the miter saw. If they can, they must demonstrate how; if not, they must explain why. This will allow full-time staff to assess the users' ability to make sound judgment calls in the woodshop and prevent the risk of injury.

3. Update safe operating procedures to include minimum and maximum allowable workpiece dimensions.

4. Update safe operating procedures to specify that the workpiece must be adequately clamped or supported on both sides of the cut fence.

5. Place tape outlines on the table to indicate the minimum allowable workpiece size.