Steph what colour are his nails? If they are white you should be able to see the quick fairly easily, if not get a torch and shine it through the buns nails, this will show you where the quick finishes. We usually cut ours and any boarders a few mm's away from it. Be very careful not to cut the quick though as this can be uncomfortable for your bun and it will bleed profusely, if you dont have any styptic powder you can use cornflour to stop it if it happens. Some small animal nail clippers are the best thing to use. HTH