I use one of those little nail grinder things, because I don't want to cut the quick, and hurt my pups. The noise of the grinder scared them a little, at first. But, if you train them a little, and don't be so direct, and in a hurry to do it, they'll calm down.
I realized, when I'd go to trim their nails, I grab the grinder, and tell them to come to me. Then grab their foot and go right into it, and they'd panic. Now, I get the grinder, and sit down with it. I'll hang out for 15 minutes or so, just watching TV, and the dogs forget about it. Then, I play with them, but set the grinder to where they can see it. Next, I get them to lay down, and start touching their feet. Eventually, I pick the grinder up, and work into using it.
It took all that, to make them calm, but now they don't mind it much.