try something called muriatic acid. I hear it works well. Olso, try sand/media blasting. Other than that, all I can tell you is sand, sand, sand. Of course, a small electric sander will speed up the process on the large frame areas. But let me ask- why do you want to strip it? Do you plan to paint it, or some other form of finish, like powdercoating? If all you want to do is paint, give it a good sanding with a fairly heavy grit sandpaper, cover it with primer and you should be fine.