We don’t have a squareness problem when sheeting a 50” wide roll. However, when we slit the same roll into 2 piles, 25” across, one sheet is square, while the other is not. What is causing the sheets to be out of square?
Check your draw roll section to make sure the cutter’s draw drum and squeeze roll are properly aligned. Remove the before knife doctor board to ease the ability to measure alignment. Using a plumb bob, measure the distance from the plumb bob’s line to the nearest point on the squeeze roll and the nearest point on the draw drum. The difference between these two measurements should be the same on the operator side and the drive side.
A more radical approach on stationary bed knife design is changing the ‘shear’ in the cutter. Shear describes the angle of the cutting helix across the width of the cutter. Reducing the amount of shear will help minimize the problem, since less angle across the cut requires less adjustment for squareness. On the other hand, less shear in the cutter also increase the noise level of the cutting action. It’s best to consult with your sheeter manufacturer if considering this approach.
Like sheet length accuracy, there is always some variation in squareness. Most operations typically adjust squareness to split the difference.
