"used to " = made familiar with or accustomed to. Example: I am used to having tea and toast for breakfast. ( it also takes an infinitive or implied infinitive) used as an auxiliary to express habitual or accustomed actions, states, etc., taking place in the past but not continuing into the present . Example: I don't go fishing these days, but I used to catch fish here every day. "used for" here "for" is a function word to indicate an action Example: A spade is used for digging in the sand. A knife and fork is used for eating your food. A hairdryer is used for drying your hair.

There is another possibility than the one Jura gives (though she may be right). "I use a hammer to pound a nail." "I use a hammer for pounding nails." With the gerund (-ing form) you would use "for". "To" simply takes the infinitive (Jura, correct me here if my use of "infinitive" is wrong).

You use a hammer to pound nails. **"The hammer is used to pound nails." We don't really use this form in the passive. Instead we say: A hammer is used for pounding nails.

I like it :) that's great thanks all