Roger If you download Charlie Dockstader's valvegear program (best not done on dialup..) there's a Zeuner diagram program in there. There's are at least two more diagrammatic methods. One is a Reauleaux, and I can't remember the other. I only came across it the other week and determined to investigate it more thoroughly, but since I've forgotten it, I can't! Just to confuse matters, the term "Zeuner Diagram" also seems to relate to another diagram to do with population. JohnP MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.