Using a smaller tool will produce less cutting force. As mensioned earier in this thread feeds and speeds have to do with Machine, Cutter, and Part Rigidity. In other words you have to aquire a FEEL for the Cut. That is why the best CNC Machinists were the Good Manual Machinists of days long past.
You will develope your own feel over time and be able to look at a Machine, set-up, and know what Feeds and Speeds to start at. A word wisdom, HSS takes less HP and Torque to run over carbide on manual machines. LOL, I use carbide anyway, because, I like too. You will develope your own methods and ideas. As long as you can make a good part in reasonable time, your fine.
Just my 2 cents
tobyaxis
