I participated on the original thread and wanted to provide an update.
First, about the edge being square, I would say that a little light showing through when you put a square up to the edge is fine. I have noticed that almost none of my chisels or planes have parallel sides, so if you reference off one side when sharpening and the other when measuring, you will see that kind of variation. The problem is if the micro-bevel can't reach the edge of the tool or if it is so far out of square that you can't adjust your plane to take a full-width shaving.
My problem was that a portion of the bevel, specifically the "right" side, near the outside of the abrasive disk, was getting ground down more than the rest of the bevel. This was particularly bad with the
80x abrasive and made it difficult to get the micro-bevel to go all the way to the edge. The micro-bevel would reach the edge except for the last 1/8" or so. Just before the right edge, the secondary bevel would taper off and the micro-bevel would not reach the tip of the blade.
I have been working with Lee Valley support on this issue and they have been responsive (as usual). They sent me new platters and new abrasives in different grits than I had. The grits they sent me were
120x, 220x, 500x, 1200x. Using these grits and the new platters, I was able to consistently grind a good primary bevel and secondary bevel. I really like the 120x and 220x abrasives. The 120x is still pretty fast, but not nearly as brutal as the 80x. It seems better for cases where the bevel is already pretty close.
Like I said, using these new abrasives, the machine worked well. I have become convinced that the problem I was having was related to abrasive wear. I think what happened with my old 80x is that I ventured near the edge of the disk, which was seldom used. The abrasive was not worn down as much, so it cut much more aggressively. That made the bevel not flat, which made it difficult for the 9 micron reach the tip of the blade. This is not a phenomenon specific to this machine. The other day I was using the Scary Sharp method with 15 micron paper and when I ventured too close to the edge of the abrasive, which was new and sharp, much more metal came off part of that part of the bevel. I have not yet worn out these new abrasive disks, so I don't have a feel for how long they last.
I asked Lee Valley if there was a way to take the blade off the edge of the platter or something similar to make the abrasive wear more evenly and the answer was a sophisticated version of "not really."
Mark