Measure Twice, Drill Once

Once more I was sent to a bank to work on a Banking On Line installation.  On this particular job I needed to drill a hole through a concrete wall from a hallway into a room with a plethora of file cabinets.

We didn’t want to move all the file cabinets, and the drill we were using required water cooling.  The hallway did not have sufficient room to set up the drill, so we covered the cabinets with visqueen and set up a hose with running water to cool the bit.

I was told that the wall was filled with rebar made of steel, not iron.  Whereas we would have been able to cut through iron, the steel rebar would perhaps ruin the bit.  I got a blueprint of where the rebar had been placed in the wall.  There was no reference point inside the room with the file cabinets to determine where the rebar was.  It was necessary to determine the location from the hallway area.

In the hallway I carefully measured to an exact point where the rebar was located and marked an “X” in a location as the place I wanted to be sure to miss.  I then calculated the distance from that spot to the floor, measured 30 feet along the floor (a sloping floor), then I turned and measured down two steps and 8 feet laterally, then I turned again and measured up a step and into the file cabinet room 20 feet, then I turned and measured behind the file cabinets, and finally I measured back up the wall and put a dot on the wall where we would be drilling.

The “we” in this instance was a young apprentice that was helping me do all the measuring and marking and would be assisting in the drilling procedure.  I could tell he was doubtful that this method was going to work.  I didn’t tell him, but I was also doubtful.

We got on top of the file cabinets.  One of us would handle the water hose and the bucket to catch the water.  We took turns handling the drill and hose and bucket.  The drill bit was actually a hole-saw that cut a core out of the cement.  We would drill a while, pull the drill out and break out a piece of the core and drill again.  When we finally broke through we pulled out the drill and the last of the core.  There, right in the center of the core was the “X” I had made on the hallway wall.  The spot I had intended to miss.

I said to my apprentice, jokingly, “See how close we measured?”  We cleaned up our mess and I looked in the hole.  We had just skimmed the edge of one of the rebars.

The apprentice was called to another job our company was doing downtown and I finished up at the bank.  Then I was also sent to the same job he had been sent to.  The guys on that job said the apprentice had told them of measuring down the hallway across the room and up the wall and hitting the spot right on the mark.

I tried to explain to the other guys that it was the spot I had intended to miss.  Somehow they wouldn’t believe me.  I guess I had built up a reputation by that time.

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