So we were fitting a Ceriani fork to an Amen rigid 750 frame... But the stem was to short. ...the top bearing area ended just underneath the top race. We wanted rhe front end on now, and did not have time to make a new stem. ( I will have to make 2 anyway)..
So here is what I did, if you cannot follow I will post a drawing..later
I chucked the stem in the lathe, got the race area to less than a half thou runnout.. A lot less.
Then I cut a groove in the threaded part, right beside the bearing area. Groove was .400 wide, and approx 60 thou deep. Got the bottom same size all the way across.. Threaded portion was gone
The stem in the groove i cut measured .925. The race area measured 1.024. Then I made a bushing. 925 id, 1.024 od, and .39 wide out of leaded steel.. Next I chamfered the inside of the bushing, then sawed it in half, ending up with two pieces that looked like bearing shells.
Now i tested it and it fit nicely. So I greased up the races, added the balls slid the stem up thru. Then I installed the two half shells in the groove..which was right where the balls sit in the race, then slid down the top race, a few light taps, and it slid on over the split shells.
Nice and tight, no movement.. It worked but, I will still make a stem for later as it will need a dustcap.
Might save the day if you ever get stuck when converting front ends...