I manufacture extruder screws according to the link below:

https://www.youtube.com/watch?v=J3nu4bWsJjM 
I want them to be individual screw segment elements, which will then be welded. 

My question is how to make such a screw (with each segment separated for welding) so that its segments gradually decrease in size. 

Do I have to do this segment by segment each time, sketching separately? But how can I maintain the dimensions so that they (the segments) remain intact: end-beginning; beginning-end. 
Individual segments will be made as single sheets.