It was brought to my attention that a large problem with the encoder input for positioning is that when a person rotates the router it looks like a move left or right instead of a rotate. To keep the simplicity there I would like to keep the encoder for positioning, so here are my thoughts. Move the GT2 belts to the bottom. Make sure there is nothing to get in the way of them for 180 degrees. Find some way to move the first point that the belt touches on the shaper as close to the bit as possible. Then they need to do their best to keep it straight.