The cutter heads are normally turned by hand and the angles are fixed so they are always correct. The cutter head for the throat angle can be ordered with a top narrowing angle on the opposite side of the head. Likewise for the popular size range, you can choose a cutter head with the top narrowing and seat cutting angles on opposite sides.
The seat angles you require on the cutters can be specified to suit your exact requirements and you can have the choice of cutter heads with either 3 or 5 blades per side (more on the sizes over 2").
By utilising cutter heads with 15° or 75° blade angles it is possible to produce three angles on the seat which allows you to control and maintain a constant seat width throughout its circumference