Using A Steady Rest????

I am making a lead screw (not for a machine tool) and struggling. The target size is 0.750, the blank is about 19" long and material 316SS - then 15" of 3/4-10 thread. I started with 1" bar (being what I had on hand) and when simply cutting with only the chuck and tailstock for support, found the vibration excessive for any decent cut. So I took it down to 0.77" by advancing 5" at a time out of the chuck (still with tailstock support) - getting it roughed out was pretty quick.

Now I'm...

Using A Steady Rest????