Tech Talk
What is the object of using a "Scoring Blade"?
The object of using a scoring blade is to eliminate chipping on the underside of laminated materials. This is accomplished by having the scoring blade cut the laminated surface before the full board is cut through. The scoring blade is always just ahead of the main saw blade and runs in the opposite rotation to the main blade. It is actually climb cutting up the board, which, because it only cuts one surface, guarantees a chip free score.
Scoring blades have adjustable kerf (cutting width) to allow for variations in the kerf of main blades and to allow for variation in laminate thickness'. With tapered scoring blades this kerf adjustment is done by raising the blade deeper into the cut, to widen the kerf, or lowering it, to reduce the kerf. There are also split scoring blades available that are adjusted by adding and subtracting shims between them. This type is rarely used now, however, because they are too time consuming to set up, and can't be fine-tuned like a tapered blade can. The only problem with tapered scoring blades is that, often they are set up to cut too deep, leaving a bevel on the edge of the boards. Ideally, scoring should only be to the depth of the laminate. This will vary slightly, with use and re-sharpenings. However, if you have to go considerably deeper, to eliminate chipping, then you are either using the wrong scoring blade, or there are other problems, such as blade run-out, alignment, bearing wear, low bar pressure, and/or many more possibilities.When purchased new, the main blade should be the same kerf as the scoring blade, at it's narrowest point. As they are sharpened, both will lose a small amount of kerf and will remain compatible at approximately the same scoring depth.Scoring blades always carry the same load. They are always cutting from 1/64" to 1/16" deep through one layer of laminate or veneer.The load on the main blade however, will vary with the number of sheets being cut and the number of laminate surfaces being cut (i.e.; a 6" stack of 1/2" Melamine coated MDF will cause more blade wear than a 6" stack of 3/4" material). Machine and blade manufacturers try to design their products so, in average conditions, the main and scoring blades will wear at the same rate, and need re-sharpening at the same time. But, this isn't always the case. We have often found that one scoring blade will last as long as two main blades, reducing capitol and maintenance costs. Whether this works in any particular application can only be determined through testing. The counter-argument is often that you have to maintain main and scoring blades in matched sets. While you can't put a new scoring blade on with a main blade on it's last legs, you can use a main and scoring that are roughly at the same point in their life cycle, without compromising the quality of the cut. The idea that if you don't have the sets matched they won't work is an over-reaction to what you are trying to achieve. This is demonstrated more and more where Panel Saw users are installing Diamond Scoring saws. One diamond blade is used with any number of carbide main blades in various stages of wear. Obviously, setting up a diamond scoring blade with a carbide main requires a reliable and careful operator, or set-up man, but it is not difficult to accomplish. Scoring with diamond is not for everyone, but I would strongly recommend that the economics and feasibility of Diamond vs. Carbide be weighed in any production application.If chipping is a problem, and you are sure the scoring is set up accurately, contact both your blade supplier and your machine maintenance people, but first determine where the chipping is occurring - top or bottom; left or right; center of the stack, or any combination of these. This information could be critical to diagnosing the cause, that could be (as noted earlier) one or more machine, or blade problems. Don't compensate for chipping by over-scoring. The product will be poor and the cause(s) will only get worse. by: Doug Reid, President, B.C. Saw
