Stem Preparation
From Pvdwiki
Why
Threadless headset systems require a nice sqare face to push against for proper function. Rarely is a cast or fabricated stem faced with any usable precision. You must do this yourself. Machined stems rarely require this treatement.
How
A simple madrel is made to fit a 1" collet and the 1.125" stem. I prefre to do all work with a collet if I can.
Very carefully spin the stem on the lathe. Take as little metal off as needed to get a nice face.
Always bag and lable specially made tools. Years later the tool will be clean, in good shape, and clearly marked.