To secure my four 10 inch alnico speakers to the baffle board I built. I purchased 1/4 inch bolts, along with washers, lock washers and nuts. When I tightened the nuts enough to compress the lock washers, I was getting what I think was voice coil rub when playing notes on the low E string. I didn't over torque the nuts, but apparently it was enough to deform the speaker baskets. Fortunately, when I backed off the nuts the voice coil rub is gone, so I haven't damaged the speakers. Right now the nuts are just finger tight, so the lock washers aren't doing anything, but over time I don't think finger tight will be enough.
I have thought about using NYLOCK nuts and doing away with the lock washers. Would a 1/4 turn with a wrench or socket just past finger tight be sufficient? Hopefully someone has some experience in this area that will help me avoid damaging some fairly expensive speakers.