Your life may depend on it.
Machine tools don’t care what you look like. They have demons inside just waiting to grab something and make a real close but very dangerous friendship with you. It’s better to have things like sleeves and hair tucked away where the machine cannot grab. It’s better to be safe than stupid. Don’t spoil your fun by being stupid. I’ve been banged or cut up enough times to know what that’s like far too many times. Besides blood doesn’t look good on your parts.