Ok, I spent a looooong time building the excavator arm, and getting all of the motors to do what I wanted them to, but......
it was always a compromise between making something that I could fit the motors into, and making a scale model of something.
I thought that I was doing pretty well, but experiments and tests over the last week have taught me that there is going to be no getting away from the interference between the three RX18 boards and receivers that I have jammed into the lower hull. The AEV almost launched itself off worktops and the kitchen table a few times, it became totally unpredictable, and the range was reduced to a few yards. I even tried Alwyn's suggestion of three RX's onto one antennae but that didn't work either.
So, back to square one.
Designed a whole new excavator arm in Openscad, it had to be done in three sections, and despite my crappy engineering skills it has just come off the printer, and when clipped together it is exactly the correct length. This version will be static, or moved under human assistance as it has all of the hinges preprinted. Nowhere to put the motors though as the new sections are not hollow.
I intend to complete the build using the new arm, the dozer still functions, then if I need a project next winter I will take another look at it. I can modify and reprint the arms if I can figure out how to make a scale version work like the non-scale one did (eg cables running in PTFE tube, servo's, pet hamster etc. I have a few ideas knocking about but I have had enough of this problem for now.
RobG
Re the electronics I don't suppose there would be any mileage in put foil wrap around/between the receivers and rx18s to shield from interference between boards? It seems an awful shame to have come so far and be thwarted on the last lap as it were. 
Alwyn
Alwyn
