On the Lathe today. Essentially these are the same part with different threads. It was a threading exercise. The thread is M36 with a pitch of 2. The 1st on the left has a right-hand thread, the middle one has a left-hand thread and the one on the right has a double start right-hand thread. They are 3 modifications of the same program. The right hand thread was done using a conventional threading cycle. The left hand one was achieved using the same cycle but adjusting the Z axis co-ordinates so that the threading tool runs in the opposite direction. The double start was achieved by doubling the pitch and doing 2 runs - the 1st from Z4 and the 2nd run from Z2. It was a very interesting project. Later we're supposed to be doing a part with internal threads that screw on to these. Hopefully I'll get to mill some of my remaining CAM programs next though. I've 3 programs ready to run on the CNC milling machines.