Hi all, my first post here, I've succumbed to some help if possible, i know its wrong but it's getting my goat! now, and many times in years gone by. I am building something as always, and reverse engineering exisiting drive components to select suitable new ones if that makes sense. In particular I am looking at a screw helix mathemtically (trying). or should i say just a screw. what i want know is the relationship between : the torque applied at a radius of a screw, and the linear resultant force. taking into consideration of course the helix angle, or i think, the helix angle. as that has a relationship with the force output, through an angle. for instance, a screw thread with diameter 8 and a lead (pitch) of 2.5 between threads. using the trig formula inv tan = opp / ADJ and modifying slightly to add 'pi' , as the helix angle is using one full circumfrence of the screw against one pitch. and we are not working in 2d anymore. inv tan = ( opp / pi.ADJ ) gives a helix angle of 5.68 degrees, great, the helix angle. now, what i would like to know is how does that helix angle now affect the output force as a multiplier, forgiving friction, with regard to what is input (torque/any) through the handle . i can see it is a ratio, and it changes uniformly, it is a decimal number, a mutliplier, how is the geometrical ratio now expressed?, how much force is output through a helix angle, any!.