I re made the safety shaft after I remembered to use the compound slide at 29.5 degrees for thread work. The first shaft was machined using only the cross slide and the threads were galled and rough. Using the compound and feeding depth there only, the finish was much better and I was able to make the 1" end a little tighter by staying back .001 on the finish cut.
Procedure:
1) Turn Dia
2) Cut Grooves.
3) Cut Threads, 14 per inch, using compound at 29.5 degrees