Laundry Cart Cap with set screw

I have a laundry cart with a bar across the top for hangars, but the only thing to keep those hangars from sliding off the end is a slight upturn. Hangars slide easily enough that a little bit of momentum will carry them right off. So I designed this simple sleeve with a hole for a set screw to provide a barrier. It's not a big barrier, but I don't think a big one is needed, since it's just stopping them from jumping on their own when the cart is rolled.