Maybe this will help to understand what you’re seeing…or maybe it won’t.
The bevel angle is fixed only on a circular line projected radially around the center of the pivot point and offset by half the thickness of the block. Anytime you leave that arc of travel, the angle changes.
As the block follows the curve of a blade, the actual bevel angle rotates with the block, which tends to remain flat against the blade and aligned with, but offset to the pivot point.
To see this clearly, take a block with your hand and hold it against the top edge of the vise. Look at the angle and see what the bevel would be. Now take the block and rotate it away from you and hold it against the opposite (vertical) side of the vise. Now look down on the block and see what the bevel angle would be. Not the same, is it? This is the geometry effect that changes bevel angles as the blocks move along a blade.
I first saw this when I tried sharpening a very long jerky knife, which is completely straight and about 12″ long. It was obvious that the bevel angle at the far tip was going to be higher than nominal. I also noted that if the tip had curved down, the bevel angle would have been lower than nominal.
When you select an angle for sharpening any knife on the WE rig, you have to accept that this is a nominal, and that actual bevel angles produced along the edge are variable, depending on the curve and length of the blade and its position in the vise. The big advantage of the WEP is that the angles are smooth, flat and repeatable.
By the way, jerky knives are known to remove bits of fingertips at the far extension of the rods. Always keep your fingers behind the block face – don’t leave your pinkies dangling.
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