The Case of the Miscalculating Rock Saw

THE MYSTERY

A quarry providing limestone for construction and landscaping called ACES because their rock saw wasn’t cutting stone to the proper width. The saw operator had to subtract 18” from each cut to arrive at the proper stone width.

THE CLUES

The operator said the problem began after an encoder bracket was installed. The CSI on the case removed the bracket with no improvement in the problem. Upon further investigation the CSI ascertained that the full 430” travel length was off by 34”, and the error varied along the track — sometimes positive, sometimes negative. Replacing the encoder bracket had no effect.

THE PERP

Finally the CSI determined that the operator wasn’t measuring and entering the blade width data into the computer for proper stone measurement. The 34” error was traced to the rack gear on the gantry. Turns out it was not installed correctly producing positive and negative errors as the saw moved down the track.

THE SOLUTION

After the CSI trained the operator to regularly measure and enter blade width data, the rock saw cuts proper stone width every time. The improperly installed rack gear was not changed as the measurement error within a block of stone was negligible.

CASE CLOSED