Over the last few years, the panning lock screw on my Linhof ball head has vibrated completely out of it's threaded hole 3 times while traveling. I have tried a heavy grease which did little, and I have not been able to find a screw with a nylon insert on the side of the threads this small to solve this problem.
Eureka! I added a conical compression spring on the screw shaft under the knob with the small end toward the knob and the large diameter end against the head. It is now preloaded so vibrations don't slowly rotate it off, and I won't be searching all over the floor of the trunk trying to find it. It was probably only a matter of time before I eventually dropped it in the field. I had even taken to carrying a klutzed replacement in the glove box in case.
I purchased the spring from McMaster-Carr. FYI, conical springs can collapse entirely down to about the thickness of the spring wire. Straight compression springs can not collapse to less than the total number of coils x wire dia.
Eureka! I added a conical compression spring on the screw shaft under the knob with the small end toward the knob and the large diameter end against the head. It is now preloaded so vibrations don't slowly rotate it off, and I won't be searching all over the floor of the trunk trying to find it. It was probably only a matter of time before I eventually dropped it in the field. I had even taken to carrying a klutzed replacement in the glove box in case.
I purchased the spring from McMaster-Carr. FYI, conical springs can collapse entirely down to about the thickness of the spring wire. Straight compression springs can not collapse to less than the total number of coils x wire dia.
