I have a Clark CMD1225 mill/drill which is, I believe, a ZX25 clone made in Taiwan. Their current version is the CMD1225C which, I'm told, is made in China.
I'd always assumed that the screw threads were UNC but, when I tried to fit new 1/2" UNC nuts to the column clamp bolts, they didn't fit. The bolts measure 12 TPI, i.e. 1/2" Whit pitch (UNC is 13 TPI); so do the 1/2" socket cap screws which bolt the column to the base.
Is it common for Taiwanese/Chinese m/c tool manufacturers to use Whitworth?
Whilst on the subject of Whit and UNC (for diameters where the thread pitches are the same) I've read lots of dire warnings about mixing male and female of different thread forms. I'm quite sure that I've occasionally mixed them and not noticed any resultant problem but they haven't been precision fasteners torqued to the eyeballs.
Has anyone had known problems when mixing thread forms?