30 move against their respective bias springs 34 36 and 38 but always along an arc generated by an extended radius of the fixed roller associated with the nip space being adjusted at any given time the exception of roller 26 of course is apparent and will not be discussed each of the first lever arms 47 66 79 and 81 and a lever arm 96 associated with roller 26 has an associated cam element 98 1 98 2 98 3 98 4 and 98 5 these cam elements are lockably pivotable about shafts such as 100 associated with cam surface 98 4 and have weighted armmembers such as 102 also associated with cam surface 98 4 in operation in order for the various nip spaces to be automatically adjusted the cam surfaces 98 are unlocked by an unlocking means not shown in fig6 but see description of fig9 so that the cams and weighted handles 102 are free to rotate about their mounting shafts 100 a piece of stock is then fed through nip space 1 as movable roller 26 is thusly moved away from fixed roller 20 lever arm 96 moves a corresponding distance downwardly and cam surface 98 1 is rotated by its weighted handle in a counterclockwise direction to engage the surface of lever arm 96 the cam surface 98 1 is held in this position by tension caused by the spring mechanism 34 as the folded stock next progresses through nip space 2 roller 28 is moved away from roller 20 by a.