In general, Ridgebacks absolutely hate to have their nails done. I have one that requires three people usually, two to hold and one to cut/dremel and I often have to use a muzzle. I would suggest putting a leash on him and either standing on the end while you dremel or tying him to something where he can't get loose, then be very firm with him. If he looks like he is going to bite you, use a muzzle. Better safe than sorry. The one I have to muzzle, usually wags frantically and gives me lots of kisses when I take it off. I know it is all an act, but it's very disconcerting all the same. They will also scream like you are going to kill them but again it is all an act. Only time you have to be really careful is if you are using clippers, then if you quick them they are going to remember and it's going to be harder to do them the next time.
Caroline