If the gibs are tight and setup is right try 29 degrees it might make a differenceI have the MicroLux 7X16 mini-lathe from MicroMark. I'm using the compound set to 30 degrees.
I run the lathe at very low speeds to stop the cut in time. Probably in the 30-40 RPM range.
If I take deeper cuts, I'll get chatter and/or the tool with jam into the work piece and jam up everything.
cutting on the leading edge only
I also own a 109 craftsman lathe bought in 1970
Did some threading on it definately had to go slower
All said those are nice threads you did