Yes,. Assemble the lower race with bearings and measure. Do the same on the upper, and add them up. The races can tilt to an angle when they're out of the bike, so you need to take some care to measure with them held parallel, not easy exactly but doable to within a mm or so, which is all the precision needed usually.

BTW upper stack height is traditionally taken to the bottom of the lip in the locknut. If you measure to the top of the locknut (cuz it's easier), just subtract the thickness of the lip.


I think your proposed lathe setup should be OK as long as you take light cuts. Clamping down too hard with the chuck will make indents in the thin edge of the part, so you have to clamp lightly and then cut lightly.

Lathe-turning the seat on the fork is easy too, if your spindle bore is large enough to take a 1" steerer "choked up". If the spindle bore is too small for that, then your lathe is not suitable for turning fork seats. Still technically possible with a steady-rest, but not recommended IMHO.

Here's how I like to do it, fork held in a 5C collet rather than a chuck. Less stickout past the spindle bearings, and best concentricity.



I can't do modern "OS" steerers that way though, have to use the chuck there, and honestly it works just fine. The extra concentricity of the collet is not necessary for bike parts! Or if it is, you could dial it in with a 4-jaw chuck.

Mark B