Hi Nick ,
Progress pics for you:
Here's the problem..1-1/8" threaded Manitou crown way too short at 150mm, needs to be 210-ish.
Plan of action, cut steerer down, insert internal sleeve, fit threaded extension.
Cut needs to be low enough so that the stem quill won't foul the internal sleeve:
I didn't have a spare threaded 1-1/8" steerer, so needed to cut a thread into a threadless tube...over to the lathe.
A bit of tool chatter early on, but all smoothed out easily enough by the final pass.
Over to the mill to cut a slot for the lock washer tab:
File thread edges to clean off burrs and ready to go:
Because the cut was quite a long way down the steerer, I had to ream out a small section of the internal butt in order to get enough overlap for the 1" internal sleeve. Also helped to clean out some of the crap from the inside of the steerer:
Flux and locate 1" internal sleeve ready for brazing:
More to follow:
All the best,