And you did in a most verbosemanner. I can't decipher your ramble butit appears you have made a very simple engineering concept intogobble-de-gook.
There is only one proper frame alignment. The bb shell is the starting point, the seattube, head tube and dropouts (both sets) are all aligned with respect to the bbshell. When that is done correctly,there's no question the wheels are aligned and the bike tracks straight. It's not rocket science, the concept wasclear to me when I was first introduced to it at 15 years old. That's how Mark Mueller does it at Waterford,I assume every competent builder understands it.
As I was introduced to the simple view of frame alignment40ish years ago too. But you know, we learn and can understand the greatersubtly as we go forward and listen to others who are smarter then we are. As Ihave. It was a few handfuls of years ago that I first heard of the separationof the steering/tracking alignment from the bio aspect. It made a lot of sense,some of which I had experienced with the frame I built just before theEisentraut class (this was the one I referred to with a badly twisted shell but"perfect" handling).
Initially in my frame working (before I actually brazed thefirst one) I did all my aligning WRT the BB shell. My really bad shelled framedrilled the point home in an uncomfortable manor. That both a steering/trackingalignment and a bio one were needed for a complete frame/fork. I just didn'thave all the needed foundation yet to truly understand how it all ties intogether and at the same time is separate.
I used the campy straight edge in the beginning (did youknow that the straight edge was just so wide as when placed against a 70mmshell face it's other edge would graze the inside of the 120mm spaced rear dropout?). next up was clamping the shell's face to a flat surface, back then thiswas a piece of Mic6 AL plate. Now I could start to control the main frame tubesincluding the top tube. But a 3/4" thick plate large enough to allow theframe to be checked is both heavy and subject to gravity in not well supported.Around this time the NECA alignment system came onto the market. Somehow I feltthat running the alignment through a bearing (with little aligning support init's self) wasn't a very repeatable process. (And my discussions in later yearsconfirmed this as far more experienced builders told me of their frustrationwith this system).
In the early 1990s my late wife gave me a really cool gift,a proper cast and hand scraped precision flat surface. Now my measuringreference would be far more consistent. A dial indicator later and I could seethousandths of an inch. So what did I learn? That reclamping a frame on thesame side of the shell resulted in different readouts and that flipping theframe had even larger differences. (This is after facing with campy BB tools ofcourse). I went on to measuring a lot of frames over the next few years. I sawthe measurements of shell to tube alignments changed with each reclamping. Isaw frames with no known handling issues having easily measured Bb twist. I sawtubes that were not straight on bikes with wheels in proper plane and shellspretty well aligned WRT the ends of said tubes. I learned that because youcould see thousandths of an inch didn't mean that much sometimes.
A Bb stand off post (sometimes called a "whipping post)that was both hardened then surface ground aided my handling the frame aligningstuff. Machinist's jacks, steel leverage bars, head tube centering cones allmade the checking and bending of a frame far easier and more controlled. And Ibecame happy, feeling I had at last found my method and understanding. By now Iwas separating the shell's alignment from the frame's steering/tracking one.(Although I had yet to put this into words, it was a conception/a theory I wasworking not having to talk about it to others).
I was measuring the seat tube's slant WRT the flat surfaceover a known distance then comparing this to the headtube's slant over the samedistance. I knew that since the clamping of the shell was a variable I neededto get past that and instead create my virtual plane of reference. I still usethis method during my actual bending of a frame into alignment.
Then along came Keth Bontrager, Jamie Swan, Kirk Pacinti(and a few others) who posted the idea of fixturing the head tube to the flatsurface via a through rod/cones and single point supporting the seat tube. Wow!years of my understanding and evolving practices came into focus. I soon hadsuch a tool (thanks Alex Meade). Now i found that my repeated reinstalling aframe had far less drift from each measuring session.
They (and I apologize if I have the names wrong) separated the shell's alignment from the restof the frame. This is not discounting the need for either shell based aligningor headtube fixed alignment being properly done. This doesn't make one better ormore important then the other. But it offers a tool, a view, an understandingto how what at face value seems to be a simple goal is really a more complexsystem.
But there is more then two ways to skin the alignment cat.Some builders (and one who is known for his frequently red bikes) chose to workoff the shell face. But they use but one side during the building process. Theymight even only face once after the shell is fully brazed. They allow for otherrealities to exist if they were to check for them (and I hope I have described their method properly). I prefer to explore and findmy method and understandings.
I will end with the claim that shell based alignments do thesame thing that my methods aim to do. All aspects of alignments are in order,all components, the rider are centered/planar/symmetrical (unless designs callout otherwise and it does happen), the handling is consistent, the fit isagreeable. The guy who does my painting, and who has taught hundreds ofbuilding students for decades, uses the methods I do but with a slightdifference to check for frame straightness. He places a frame's seat tube andhead tube on parallels on the flat surface to find rock. No shell clamping. Yethe uses the shell clamping during his building process.
This long winded post started as a rebuttal to XXX’s reply to my earlier post defining the aspectsof alignment and how they are different from each other yet do interact. I hopehe and others now have a fuller understanding to my views. Andy.