Rvjimd-I wasn't sure if you were interested in this but myself I like to learn about other things. On the drag rope lengths, I think you are doing the right thing by experimenting. Most machines especially models are different. As you have seen the drag ropes affect the way the bucket dumps and carries. I think the correct position for the bucket to carry is with it slightly tilted back when hanging under the boom point but this is hard to achieve on a model because of the lack of weight. Just work with this and get it the way you like and the way it operates the best. Also adding weight to the bucket is good if it makes it work better and if your servos have the strength. On the big gear I think you are correct. They are used on smaller machines and I believe they act as flywheels to keep things running smoothly.You could possibly use a small electric motor to run this gear slowly and continuosly and it would look really good but I'm sure you can work this out. As far as casting I think only some small machines can do that and they must be equipped with clutches and brakes. Where you are working it looks like your boom is long enough so you probably don't need this. Watch this video and you can see that the bucket is almost dumping as he is swinging-
http://www.youtube.com/watch?v=3GX481pFhE8