well i have done Steps 1 and 2 with no significant improvement . im pretty sure that in my case the heated bed is causing my banding . my layer offsets are not in a particular pattern . .as we usually see when Z banding is caused by threaded rods wobble .

Im curious about the SS relay but i dont know how this work . for what i understand the rambo board (what i have on my printer) is capable of doing PWM on the HB . but im not sure if it can handle the current .

Also im planing to convert my I3v 12" to all metal similar to the new model that colin have on makerfarm (Pegasus) maybe if more users are interested in this solution we can work together to come with a good design.