Thanks DK - I think I have resolved the jerk issue. Some time ago I looked at Rosetta stuff and yes its impressive but outside the hobby scope/cost area. I'm sure MC is lurking but there's not much meaty stuff on the forum at the moment for him. I'm having fun with structural design and AI, adaptive and generative optimisation design for my two new machines. Looking fwd to using Dynomotion on the upcoming machines... I'll have to brush up on my 35 year old C programming.... Peter