They work very well for pipes with parallel walls. Many pipes are drilled that way and the Pip-Net gets right down to the bottom where the Senior leaves cake because of the angle of the cutters. The only disatvantage of the Pip-Net is the fixed diameter of the cutters. That doesn't make any difference if you are reaming one of your own pipes but if you are restoring an estate pipe and want to tale the cake completely out, they can be problematical.
