Exploiting Kinesiology (a/k/a The Seven Minute Camber)

When it comes to sharpening plane irons I am a sidewinder.  I taught myself how to sharpen and this was the way that made the most sense to me as it exploits the natural kinesiology (the study of human motion) of the hand and arm.  Straight-ahead sharpening fights the natural motions of the body as you have to constantly adjust the angles of the shoulder, elbow, wrist, and hand.  Sidewinding takes advantage of the swinging motion of the arm.  All you have to do is establish the bevel angle of the iron and everything else takes care of itself with minimal attention.

The pendulum motion of the swinging arm makes it almost effortless to shape a camber on a plane iron.  This one was a new one for a Bailey #5.

My initial shaping of the bevel contour is done with a 60-grit belt on my 50-cent granite backsplash block.  My first step is to gauge the bevel angle, which I determine by setting the iron  bevel-down on the abrasive surface until the tip and the heel of the bevel are both in contact with it.

Then I start to introduce the curve on the bevel tip by rocking my body forward and backward, and swinging my arm in a pendulum fashion, moving the iron back and forth on the abrasive belt while maintaining the bevel angle.  As I am doing this I rotate my hand to push down with my thumb and grind away the trailing corner on the push stroke and press down with my index finger on the opposite corner on the return trip.  It really is almost effortless and idiot-proof.  For this part of the process I usually wear cloth work gloves as the iron gets really hot, really fast.

After I get the curved tip I want I move on to finish the iron on my 220 and 1200 diamond plates, then finish it off with the 8000 ceramic stone.  Sorry for the fuzzy pic, it’s the curse of the “Automatic” setting on the camera.  I use the exact same motion for the sharpening stones as I used for the rough shaping on the granite block.

Originally I titled this post “The 5-Minute Camber” but I timed myself as I created this one.  I was off by 40%.  It took me just over seven minutes to go from start to finish.  Shoot, I took longer to do the photography.  I’m trying to teach myself to make short “shop tip” videos, maybe this process would be a good candidate.