I've been working on two 15-20 year old steel frames with threaded 1" headsets (yes, my builds are never-ending right now).
And I've noticed that there's more variability than I'd like to see in the diameter of headset pieces that get pressed into frames and forks.
I've got a crown race that slides into place with very little pressure (I can seat it all the way down by hand). It doesn't have play, but it goes into place too easily for me to be confident that play won't develop. Two other crown races of the same official dimension seat with a more normal level of force required.
I've also got one headset cup (the top race) that slides in nearly all the way by hand, although again I have to exert some force - just not nearly as much as I'd expect. It also goes into the bottom of the head tube just as easily, so I'm confident the difference is between the two cups, not between top and bottom of the head tube. The bottom race from the same headset goes in with normal level of force.
First, how normal is this unacceptable level of variability in machined tolerances of press-fit headset parts?
Secondly, what can I do about it? I've heard of some form of loctite which are designed to make press-fit interfaces tighter. Is that the best option here?