hello i have a samona Multi-Purpose Machine AT520 mill/lathe i am having trouble selecting the right gears to cut threads
if anbody has one or knows how to choose the right gears for this machine
i would appreciate any help

for 24threads per inch i choose

i follow the manual and choose c gear50 teeth and
d gear 27 teeth
even b gear is 60 teeth
but when i choose the a gear of 36teeth

a and be do not mesh they are to small

the drawing is very hard to understand please help