1, straight knife:
Rabbet of the chamfer of all sorts of width, mill mixes usable Yu Xi mortise, cooperate to be treated simply also can do straight tenon to join or point to receive or makeup. The dimension of straight knife is very much, the most commonly used is 1/4 inch with 1/2 inch straight knife. If want mill wide at 1/2 inch groove is OK much mill two, 1/4 inch - the chamfer between 1/2 Cun Zhi can use 1/4 inch straight Dao Xi two. Than 1/4 inch narrow still chamfer?
Additional: About the choice of handle diameter: If possible sentence chooses 1/2 inch, than 1/4 inch bear fruit force.