Nail Penetration
Nail penetration can happen with ALL trigger types. Nails can pass through a work piece and either hit the worker's hand or fly off as a projectile nail.
A blow-out nail is just one example. Blow-outs can occur when a nail is placed near a knot in the wood. Knots involve a change in wood grain, which creates both weak spots and hard spots that can make the nail change direction and exit the work piece.
Nail penetration is a real concern for placement work where a piece of lumber is held in place by hand. If the nail misses or breaks through the lumber it can injure the hand holding it. As you can see in the image above, some other part of the body may also be injured.
Real World Accident
Two framers were working together to lay down and nail a subfloor. One framer was waiting and holding the nail gun with his finger on the contact trigger. The other framer was walking backwards toward him and dragging a sheet of plywood. The framer handling the plywood backed into the tip of the nail gun and was shot in the back. The nail nicked his kidney, but fortunately he recovered. As a result of this incident, the contractor switched to using only sequential triggers on framing nail guns. Co-workers can get injured if they bump into your contact trigger nail gun. You can prevent this by using a full sequential trigger.
Knowledge Check Choose the best answer for the question.
3-3. What is a special concern when nailing a piece of lumber that is held in place by the hand?
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