Hey Doug, I have done a ton of these. I may or may not do assembly a little diferent than some, but here goes. After turning and sanding, I part to the tube with a 3/16" parting tool to the brass tube. Try to clean the tube without removing too much brass, if neccesary clean the tube with a knife at assembly.Then apply finish. Put the nib parts together and slide on small ring, then press into barrel. Press threaded part on top of lower barrel. The centerband assembly goes together with the black ring, then macthing ring(I use a SMALL drop of thin CA here)Then press onto lower part of upper barrel, smaller rings to the wood. There will be a little 'overhang' of the center band. Press threaded part in for clip into top, I then screw the transmission onto the lower part, then align the grain and press the upper barrel onto the lower. I have never had any problems with 'proper' lengths on the upper that I was told about when I first started doing these. At woodworkersshop dot com, you can download instructions, but they will tell you to part off 1/4".
HTH