Why do I need to install new bumpers on the cutting cylinder or having shingle length problems?
Here’s the answer from the experts at Reichel & Drews:… The bumpers on cutting cylinders have two important functions in the shingle cutting process. First, bumpers provide tension while shingles are being cut by “pulling” the sheet from the shingle cutter measuring rolls or measuring drum through the cutting cylinder. Bumpers are there to provide constant tension, resulting in the correct shingle length, and this is the reason it is so important that bumpers – strips and plugs – should be replaced regularly and are the correct height. Reichel & Drews recommends the bumper height for strips at 1/16″ below the new knife tip diameter, and for plugs to be even with the new knife tip diameter. Note: This dimension needs to be adjusted for specialty shingles such as the double thickness of laminated shingles. The second function of the bumpers – particularly the strips – is to prevent the cut shingles and the web from “following” the cutting cylinder. The bumpers (usually strip type) are
