So, I think the problem was I spawned it too far forward and was testing on the 4g creative planet. I was able to get it to dock by adding 3 small thrusters across the top of the drill side then backing up with that thrust.

Great concept, but I'm having trouble getting the arm to dock. I think a bit of modifications might make it slightly movable and then dockable.

clever idea to get a moving part :)