if you use only glue (whatever variety), a good idea is to drill small holes all along the edge of the visor. actually, a more free flowing glue might work best on this. apply the glue along the inside of the helmet. when you apply pressure to the visor, capillary action will draw the glue up into the holes you've made and when dried, it will become kind of a "glue rivet". People use this technique to attach plastic hinges to RC cars all the time. thanks