Yes I never used a rotary and so?

Well, It's because you don't have a basis of how they work in the hand. How they should run or how you would want them to run. I understand wanting to experiment and doing things yourself,thats cool.Nothing like doing it yourself and have a machine you created but without knowing what you like in a rotary machine your jus putting parts together. To me ,I love building things on my own but i also want function with form. Thats why and so? It sounds like you got defensive when theres really no need to be ,if you are? I was just wondering why if there was no experience with them. Usually,you would use something and then try to make it better or then create your own. Good luck with your new build.