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Well, I'm still here. Seems I'm not much of a poster, or photographer, but I have a few pics to bring me up to date.I made the housing for the supercharger rotors, and the gearbox housing, and then ran the rotors together with the helical gears fitted.there was loads of interference with the rotors, so I just ran it for a bit and then removed the contact spots, and then ran it again.This time it contacted somewhere else, so I removed those points.Anyway, I went through this rigmarole about 12 times and they were still catching. It turns out that even though I'd closed the theoretical centrelines of the gears up a couple of thou' there was still too much backlash between the gears to keep the rotors where they should be.there is about 4 thou' movement at the rotor tips. This needs to be 1 thou' at a guess. I ordered some gears with slightly longer centerline and I'm going to mesh them together with grinding paste, to get almost zero backlash at the centres I'm now stuck with.Sorry for brief explanations, I don't get long for lunch here.
A street blower runs around .004 to .006 clearance at the edge to edge of the rotors.