ORIGINAL: Rafael23cc
Although interesting, I believe this is a very dangerous proposition.
From the way you are asking the question, I believe that you have zero experience in helicopters and much less in RC in general.
Why don't you pair up with an experienced modeler to help you along? Or you could buy a ready made helicopter and reverse - engineer it.
After 20 years of flying helicopters, if I knew anything about lathes, milling, and any kind of metal machining, I may give it a try.
Rafael
Yes very good advice. . . While i also admire the initiative and ability to build something from scratch you would greatly benefit from buying a cheap clone kit eg a Hobbyking helicopter kit and building it and flying it first. It could be your trainer. And the build process would give you invaluable insight into the workings of a heli. Then reverse engineer it and enlarge and or improve on it to your hearts content. .
Good luck with a very interesting and ambitious project