I just bought a Freud Diablo Dado set from HD and so far, this being my first time ever using one, it has worked well. I made my first perfect dado test cut after only a few tries. The problem I have is that the arbor on my Ridgid R4510 is not long enough so I’m limited to the width I can set for dados. Now, I see that the arbor washer is the standard concave shape all table saws I’ve seen have. Could I replace the washer for a FLAT washer that has the same thickness as the factory washer? I think that by doing that I could successfully add one more blade and still have some threads in the arbor showing. If I add one more blade with the factory washer, the nut sits flush with the arbor’s end which I read is not safe. Any thoughts or advice? What is the purpose of the washer being made in that particular shape?