If you were in my shoes.. what would you do?
A shaft is needed for a machine, 1.5" dia, but with a collar at the
middle of it. The collar needs to be about 3" od and about 1/2" thick.
Access to machining equipment is limited. No mill, and an abused lathe
that is too old with only basic basic tooling. Budget being the eternal
issue, I am planning on machining the collar out of mild steel and
carefully TIG welding it into the shaft, and then re turning it to cut
away excess weld and to make sure it's not crooked as hell. Has anyone
tried this and failed because the shaft warped excessively? suggestions
please...

I would attempt to machine the shaft from larger stock, except it would
be a first lesson on super close tolerances on the 1.5" as well as the
nice finish. overall length of shaft is perhaps 12".

Thanks for the advice
- Loren