It takes about 4 fewer revolutions to screw on the shaft:grin::rotflmao1:
On a more serious note. IMHO, there is no appreciable difference between the two pins. It's more of an arbitrary choice by the builder.
Really though, a quality made 18 thread would be a better thread for cues. The fewer threads the more of a "Jam" fit you have. The more threads the smother and more positive closure the joint would have. It would also close tighter with less effort. If it was not I guess looked down on, a cue maker would not be doing anyone a disservice with the finer thread. For some reason cue makers just don't use it other then Meucci and Huebler. I can't really see any down side other then it may get so tight you can't get the cue apart. I guess you have to do what the public wants and they associate the 5/16 x 14 with high end cues.
Does what I said make any sense? Is there something else I am missing or an argument to be made for the 14 over an 18?
Since you quoted me, I guess I'll jump back in.
Yes, what you said makes perfect sense. A finer thread is "smoother" and will provide more leverage (for lack of a better word) for tightening. However, you just don't need (and shouldn't use) that much fouce to properly attach a shaft to a butt.
My lame joke was my way of expressing my opinion about the lack of a difference between any two pins.
IMHO, the pin's function is to hold the cue together. If properly installed, any pin will serve that purpose. With that thought in mind, the choice of pin size and/or thread count is arbitrary.
Just remember, I did say IMHO
What size are the pins on the cues in your attached pictures?
It won't close tighter with less effort.
It will take more vibration to loosen it.
The mechanical advantage of a finer thread exists only with a dynamic load. For tightening (axial force), the pitch of the screw makes almost no difference.
Aside from the points already made, if gluing an 18 tpi screw into wood, a standard tap may not give the same quality threads as the coarser taps. I use the 14 tpi, so this is just my best guess (aka speculation).