Originally Posted by
joejack951
Changes in thickness, assuming the thickness is all removed from one side as it is on every chain ring I've ever seen, will not impact the tooth centerline. The mounting surface stays the same regardless of the thickness of the tab so the only dimension that can affect the tooth centerline is the offset of the teeth from that mounting surface.
No. Incorrect conclusion as I understand your argument. (What "thickness [that] is .. removed" are you talking about, the machining for the teeth?)
The mounting surface stays the same regardless of the thickness of the tab..
Possible, but there's no evidence (yet) to support that statement. Therefore we can't assume that it's true.
If you have a variety of rings (most of mine are Ultegra - which appears to be all CNC, btw), we might be able to get enough data to establish the truth (or falsity) of the statement.
A better method for measuring tooth offset would seem to be as follows: Place the ring on a flat surface and mike the height of the tip of a tooth (mark the tooth for later). Repeat for several differently-shaped teeth. Then flip the thing over and re-measure the same teeth. No need to take tooth thickness into account provided that you measure from the corresponding point on each side. The difference between each of the two measurements is the datum of interest. It may vary by type of tooth, but if there is an overall offset the difference should be roughly the same for each tooth.
Then we can correlate any discovered offset to ring thickness to see if it tracks.
I'll post a link to my thickness data as soon as I find it. Please contribute.