[Elecraft] 5119 is alive!

[Ron D'Eau Claire]

Tom, N0SS, wrote:

My shack is always climate controlled 
and although I don't SEE any deterioration of the screws, I HAVE certainly 
found that the screws do NOT want to be removed if you really tighten them 
down. Nowadays, I just 'snug' down the screws I remove frequently. They 
stay tight,  and won't voluntarily back themselves out, yet they can be 
readily removed by the right-sized screwdriver.

-----------------------------------------

One of those "Aha!" moments one gets sitting in a class that sticks in the
mind for a lifetime is this: A screw is a SPRING! 

A screw "tightens" because it is a spring. I watched a demonstration of just
how important that is. The demonstration consisted of trying to tighten a
screw made from frozen Mercury (which is not elastic or "springy"). One can
put hundreds of inch-pounds of torque on the darn thing tightening it in a
frozen Mercury nut, then remove it with nothing more than your (heavily
gloved against the cold) fingers. 

When a normal screw (or bolt) is tightened, it stretches. That's the "spring
action". The threads bind against the mating threads and  the head is held
secure by whatever is being "fastened" and the whole thing stretches
slightly. No stretch, no tightening action. 

Any action, corrosion, dissimilar metal action, etc., that takes place where
those threads are hard-pressed against the  mating surfaces will increase
the friction enormously. Consider just how long that mating surface is on
the screw - it's the entire length of the thread winding around and around
the screw that it touching the mating threaded surface. It doesn't take a
huge increase in the friction to make the torque required to free it exceed
the strength of the shaft, and suddenly you have a broken-off screw. 

The screws in things like my K2 case are just gently "snugged" down with the
proper size screwdriver. Nothing I'd call "tight", and not a single one has
ever been found loose the next time I opened it up. A little snugness
provides plenty of spring tension to hold the assembly together. How tight
do I mean? Well, I've never managed to strip the threads in the slots on the
sides of my KPA100 heat sink using the normal Elecraft screws, even though
I've removed it dozens of times, at least, over the past few years. 

Ron AC7AC