Hoko River Shake Mill
     Ever seen a sawmill saw sharpened by machine? 
     Tim van Ripper runs the cedar shake mill at the Hoko River sawmill.  Even when he doesn't run into the rare rock, he has to regularly pull the big saw out of his shake cutter and sharpen the massive teeth (in the film, you can see the swoop of the metal rim that contains the saw as the camera swings back into the sawmill after showing the Hoko River and the old sawdust burner).

     Sharpening is a three-step process. The first two steps, which usually take from five to fifteen minutes each, true the teeth.  The final process (shown) normally takes about three complete revolutions of the saw in the sharpener.  If the cedar chunk contains a rock grown into its wood, it can chip a sliver out of a tooth and then re-grinding the teeth and final sharpening can take as long as three hours.

     This is van Ripper's newest saw.  He has two others; the oldest is marked 1899. These big circular saws have been sharpened by machine since they were invented, by devices orginally powered by steam and then by electricity. They required machine-grinding to keep them true, or lined up absolutely flat to their cutting surface. The sharpeners take surprisingly little power.  All that's required is a 1-horsepower motor to turn the saw and lift and apply the grindstone.  The grindstones are replaced every couple of years.
     Note to art welders:  Tim's got some old saws over ten feet in diameter and piles of massive old gears and parts. Think of those in your next installation.