Abstract: The invention relates to a folding board for folding paper (A) of a standard size, such as stationary, to which end the folding board is provided with position checks (2,3) for holding the paper to be folded in position as well as with a folding mark (4). Thanks to the folding mark (4) it is possible to quickly and accurately fold paper in three. Further folding marks make the folding board suitable for different standard paper sizes, such as DIN A4 and US letter paper. Using the aid, paper can also quickly, easily and accurately be folded double or folded twice double.

Abstract: A grading roll is provided having parallel and circumferentially closed sinuous grooves on the roll surface. The grooves are spaced axially along the longitudinal cross-sectional direction of each groove varies twice in angle with the roll axis, i.e., from 90 degrees to a certain value smaller than 90 degrees and back to 90 degrees. The bottoms of the grooves are at a constant radial distance from the roll axis, while the cylinder surface portions between the grooves decrease in radial distance from the roll axis from a minimum at the 90 degree angle portion of the grooves to a minimum between these portions.