Lots of great info here guys thanks for all the tips.
I can only add that I have not tried 12L14 but use a lot of hot rolled cutoff scraps
and 1018 along with some drill rod and brass and aluminum.
Additional points to keep in mind are the lathe spindle speed. I find it best to use a rather slow spindle speed.
For feed speed I like to keep it relative high. Lots of cutting oil applied with a brush. (I use thread cutting oil).
Remove the compound and replace it with a QC tool post block. That will eliminate one source of movement.
Cutoff tool height is very important and it must be sharp as a razor.
Keep the cutoff tool stick out short.
Keep the cut near the chuck.