TrueGrid® uses the numbers you specify in the cylinder command as the angles for interpolation. So, for example, if you set the radius and angle on one end of an edge to (80,-15) and the other end to (60,165) and then ask TrueGrid® to interpolate a node between then, you will get the point at (70,75). This is placed perfectly between the two endpoints, in the polar coordinate system.
In most meshes using the cylinder command, you must keep all angular coordinates within a period that is 360 degrees wide. You need to also choose the minimum angle of the period wisely so that you do not attempt to interpolate from the maximum to the minimum angle of your period. The cylinder part is not a general purpose part like the block part. There are certain parts or geometry that are ideally suited to be interpolated in cylindrical coordinates. This feature in TrueGrid® makes it easy, for example, to create a helix. But for most meshes, the block part is best.
