I think you better have other reasons than, "Jim and Jack make 1/2 their labor rate and I make 1/3." Every company I've worked at has had rules that did not allow employees to discuss their compensation with each other. Maybe that isn't the case where you work, but I still think you look a little underhanded if that is your only justification for a raise. If you feel you deserve one, ask for one for that reason. Your compensation should be based on your performance, and no one else really has anything to do with that.