I was working at a yard in Seattle, Blanchard Boat. The yard was repairing a large wooden sailboat and all the rigging. Inspection found that one of the wooden masts had serious rot so a replacement was built. The mast was a hollow one. Not all hollow but large portions were 'coped out' to reduce weight aloft.

The process entailed gluing up long lengths of Sitka Spruce about 60'  overall. Then running them inverted, as in inside down, over the shaper with a 2  bladed cutter head to hollow out the interior prior to gluing the 2 halves together. It required most all the gang to handle the stick and guide it over the shaper head. First one went well and after lunch the second was prepared to be passed over the shaper.

About one third of the way through there as a tremendous "Bang" and the stick exploded and snapped in two. After the dust settled, it was discovered that there was a hole in the sheet metal wall behind the shaper and that the knives,tool steel, were shattered!

Investigation showed that a piece of one of the knives had gone through that sheet metal wall across a 12 foot alley and through a concrete block wall and wound up lodged in a typewriter which was in use at that moment by one of the office ladies. She had fainted and was taken to hospital in shock. Further investigation revealed that it was a bullet lodged in the wood and the shaper head had struck it. It could easily have been a tragedy.