I was just looking a OO's beautiful fletching and it brought up a problem I'm having. When I clamp and grind my feathers I wind up with a lot of shaft left on one side of the vane. In the first picture you can see the difference in the amount of vane showing between the black and white feathers. The second(blurry, sorry) picture shows the other side of the black feather. I'm grinding them at 90 degrees and if I was to grind any deeper I would wind up with no shaft at all on one side. I use farm turkey and Canada goose feathers and they both seem to do the same thing. Any suggestions?