I work in south carolina in construction work 4 nine hours days and one 4 hour day some times the boss ask us to work later on the 4 hour day and work on sat but they will not lets us get ot they tell us to go home early some days and tell us not to come in some days just so we dont get ot is that
with in state laws to do that

Your employer has no obligation to allow you to work more than 40 hours so that you receive overtime pay. If your boss wishes to send you home when you hit 40 hours for the week or not have you come in some days to avoid paying any overtime, that is perfectly legal.

Your post is a bit confusing so if you are saying that you ARE working more than 40 hours some weeks and aren't being paid time and a-half for your overtime hours, then that is unlawful and you may file a complaint with SC's Department of Labor.