As the title says what is the best way to take an existing sans serif font, such as Helvetica, and add a grunge effect to the text for die cut vinyl? I know it can be done manually but that tends to take time.
Take a picture of some 'grunge' or scan in some 'grunge'. Crank the contrast up in Photoshop to make a black/white image. Bring that into your vector illustration tool and auto-trace it.
Then take your letters, join them into one object. Take your grunge, join that into one object. Then use pathfinder tools to 'punch' the grunge out of your letters.