Originally Posted by
cny-bikeman
Yes, I can see your point, although I suspect the method is still sufficiently accurate. Yes, one could accomplish the goal of parallel by measuring, although multiple measurements introduce error as well. Also, one could simply take whatever position the bubble takes on the table and try for the same position on the fork column. I did suggest a 9" level. As I already noted your method seems effective, and it has the benefit of not having to clamp the fork, as others have suggested.
I don't know how much measuring you actually have to do with my latest suggestion. Until you get the adjustable pylon really close to the correct height, you'll be able to see the steerer end bob up and down as you slide the pylon along the steerer. When you have an adjustment that is really close to parallel to the table and the steerer no longer moves, you would break out the calipers to confirm what you're seeing. If it is, that's the measurement you'd use for your calculations. Other that that difference, it is just like your level idea - I'm just saying to use the object you'd need to lift the fork in step 3 as both your parallel confirmation device and measuring tool.
The problem with "whatever the bubble takes" is that this becomes a judgment call, not a measure. A digital clinometer would at least tell you what degree both are off from level. And you still have the problem of measuring level on a short length of round tubing. Especially if there is bulging around the lip of the steerer from a pipe cutter - that will make the level useless.
It is do-able, but if you truly have a mystery fork you aren't going to know whether you have level measuring errors or not - you'll just end up with an rake that you suppose is right.