-
Paint will of course be removed and cleaned.
You're going to have to go a bit further than that if you want a solution which lasts more than one ride. The headtube needs machining so that the two ends are fairly accurately cylindrical and coaxial, and sized to create the necessary press fit in the cups. This is relatively simple when dealing with the ID, since you just have to hold the head tube fairly close to coaxial with the mill spindle and run a boring head into it. Holding a finished frame in a way which allows you to perform similarly accurate finishing work on the OD is pretty challenging
gbj_tester-
The headtube needs machining
My idea is that the softer aluminium will be headset-pressed onto the paint- and residue-free but not-so-perfectly cylindrical steel heattube simply by brute force as soon as ID and OD roughly match. According to Park Tool, the difference of ID and OD can be up to 0.3mm for a press-fit to work.
Will report how it goes. If it's shit and goes loose all the time, I will machine another set from steel and simply braze it on.
By the way, what I really don't get: as there is no doubt that the brazed-on version would work nicely, why isn't this already available as a product in framebuilder catalogues.
jetski
Of course it completely depends on the frame. In the drawing it's 3mm, on my frame here I can go 5mm deep at the top and 3mm at the bottom. Paint will of course be removed and cleaned.