"powerline insulator posts 101"?

WELL OK here we go, a stab at everything one never needed to know about glass/ceramic insulator posts and their relative sizes -- based on what I've sorta newly noticed/learned about the variety of such, or at least those now amongst my actual collection thereof. SEE ALSO several of my past showings that'll be noted below for 'background', if you'd be curious. :-) The milkcrate-ful of these (shown yesterday) prompts lots of this, as I (naturally?) got to wondering why most *don't* actually fit the now relatively commonly found 'antique glass' insulators. (which I have bunches and bunches of too) Then, finally realizing that I *also* actually do have a handful of somewhat bigger (and more contemporary) ceramic insulators around here -- and now we're to what the photos here are intended to demonstrate. :-) :-) :-)

Pics 1 & 2 show (from the left) three large-ish sizes of ceramic insulators and two typical old glass ones, with posts that fit them installed and extras in front of 'em, all with a 3' (36") yardstick for size reference laying in the yard with them. (pic 2 is their undersides)

The two largest ceramic insulators have the 'big' thread, which is the single post in front of them.

The next two insulators, one ceramic and one typical antique glass, fit the 'medium' thread and are seen with two types of posts in front of them, one has 'machine bolt' threads and the other with 'lag bolt' threads on their opposite ends to fasten them to whatever they were fastened to. (not shown is that this 'medium' thread is also the same size as directly cut onto the ends of the angled wooden 'poleside arms' I also just recently showed)

On the right side is another typical glass insulator with a 'small' threaded post. THIS size of post thread does NOT come even close to fitting its insulator alone (whether the glass or ceramic examples) by itself. If you look close at it in pic 3, it can be seen that there is an additional small, threaded for the insulator on its outside, wooden 'stub' up in it that the iron post thread really does fit into in turn. This 'small' size of post is also the same as all the ones on my (again recently shown) 'cross arm beam'.

At the moment, these smallest posts are my remaining unknown about their where's/why's of existence. The short version of that is simply that I don't ever think I've (known that I) found insulators that *would* directly fit them. Also don't know if/when/why the little wood 'stub adapters' might have been routinely used with the now typical old insulators on them.

ANYBODY HAVE A (the?) CLUE TO SHARE?? ;-) ;-) :-) :-) :-)

Pic 4 here, BTW, is just one of each of my current 3 sizes of iron posts all together.

https://www.collectorsweekly.com/stories/309827-assorted-old-iron-insulator-posts-and-ut?in=all

https://www.collectorsweekly.com/stories/309760-old-wooden-pole-side-insulator-holder-br

https://www.collectorsweekly.com/stories/309421-authentic-wooden-crossbar-from-a-tracksi

https://www.collectorsweekly.com/stories/301742-three-more-ceramic-powerline-insulators

https://www.collectorsweekly.com/stories/300969-more-ceramic-powerline-insulators