Details
D454 108 SM
FM4 Letter Fold-in
In Fold Method 4 (FM4):
The leading edge of the paper is stopped by Fold Stopper 1.
The paper flexes toward the nip of fold rollers { and | which performs the first fold.
Fold Stopper 2 stops the paper and flexes it into the nip of fold rollers | and }.
Fold rollers | and } perform the second crease and feed the folded paper in exit path.
Fold Stopper 3 is not used.
FM3 and FM4 follow the same sequence but the resultant fold is different:
In FM3 Fold Stopper 1 is positioned high so a short length of paper is allowed to feed
before flexing toward the nip starts.
In FM4 Fold Stopper 1 is positioned low so a long length of paper is allowed to feed
before flexing toward the hip starts.
This positioning of Fold Stopper 1 accounts for the difference in folding at the next nip.