Microscope mounting posts

[daveismissing]

Are the posts for the typical microscope stand all(mostly)  the same diameter?, Does anyone know what that diameter might be. Speaking of the usual Ali/Bang good/whatever products.
D 

[ygi]

AFAIK, diameter is either 25 or 32mm. I'd say 25mm is more common when it comes to Chinese imports. Though, the 25mm head uses a plastic reducer to turn the 32mm hole into a 25mm that you could pop out. Look at the picture, you'll get what I mean:

[daveismissing]

Thank you so much!

[daveismissing]

And now for the real surprise - when this one (Wally Sky) arrived the hole was 14mm 

[jfiresto]

So what size shaft might it need?

I am having some fun satisfying a microscope that expects a 24½mm shaft.

[ygi]

And now for the real surprise - when this one (Wally Sky) arrived the hole was 14mm 

Welp, that unusual when it comes to binocular microscopes. Even my lightweight USB microscope stand uses a thicker shaft.

So what size shaft might it need?

I am having some fun satisfying a microscope that expects a 24½mm shaft.

That's what the diameter of my "25mm" shaft really is when measured with a caliper.

[jfiresto]

...I am having some fun satisfying a microscope that expects a 24½mm shaft.

That's what the diameter of my "25mm" shaft really is when measured with a caliper.

I would think that would feel a little loose. Mine measured 25±0·05mm.

[ygi]

Well, there's a brass ring insert inside the head mount hole that gets squeezed against the shaft as a part of the locking mechanism. That ring fits snugly into a groove in the shaft allowing the head to rotate without sliding down when the locking screw's loosened.
That's this black part to the right: