Pass the bolt through the materials to be attached and screw the lower (convex) nut onto the bolt as shown in the picture.
When the lower nut cannot be tightened further by hand, use a hook wrench, etc. to tighten it fully.
Next, screw the upper (concave) nut onto the bolt by hand.
When the lower nut cannot be tightened further by hand, use a wrench, etc. to tighten it about 1 turn further in the same ways as for the lower nut.
The self-locking effect of the HLB nut will be exhibited regardless of whether there are gaps between the upper and lower nuts or whether they are fully against one another as shown in the picture. In either case, the HLB nut’s intrinsic self-locking energy is more than sufficient, so there is no need to worry about whether or not the two nuts are fully pressing against each other.
*When installing an HLB nut, tighten the upper nut as described above until it no longer turns.