2. Split pins are frequently used to secure other fasteners, e.g. clevis pins, as well as being used in combination with hardboard discs as a traditional joining technique for teddy bears. A common application of this is when used to secure a castellated nut. One problem with this type of use is that the castles on the nut must line up with the hole in the mating part so that the split pin can be installed. When the nut is torqued properly, but the holes still do not line up, it is preferable to over tighten the nut than under tighten it.