A basic thread question

[Roger Gwynn]

I don't tend to mention it too often because of the agro it will cause but Ariel generally did not specify the thread form on drawings, just diameter and tpi but when they did it was inevitably listed as Whitworth form. To be clear I am talking about fine threads here. Considering that Ariel started off manufacturing components for the cycle trade, before moving on to complete bicycles, motor tricycles, motor Cycles and cars one would have though that they would have used Cycle thread. Although the other day I came across a drawing that mentioned the thread as Cycle!
I have always used cycle taps and dies and all Draganfly's parts are made with cycle thread, unless the parts are very clos tolerance they will fit. BSB (British Standard brass) is 26 tpi at all sizes and 55degree.

[johnmack]

How much percentage wise are machine rolled form to cut formed threads?