Snrub, you are correct. It's a standard, 1" coarse thread, 1-8 I believe. My usual source, McMaster-Carr, has the acme in stock. I actually had it in the cart, until I saw the price for the coupling nuts....no way.

Canyon, the stools are free to swing in and out, no locking mechanism. My family has been all over them, there is no tendency to kick out or fling you off.

"Forget pounds and ounces, I'm figuring displacement!"

If we accept that: MBG(+)FGSF(=)HBG(F1)
And we surmise that: BG(>)HBG(F1) while GSF(<)HBG(F1)
Would it hold true that: HBG(F1)(+)AM500(x)q.d.(=)1.5lbGRWT?
PB answer: It depends.