Good advices for a newbie (threading tools lathe)

[PJs]

Thanks for the info Stefano! Both mill and lathe look pretty substantial and good specs on the mill.

I took a look at the "Site Browser" site and seemed pretty good. I found the last paragraph of the first link interesting.

"For midrange and tweeter horns, many of the
tractrix horn advantages are lost if the horn curve is terminated before the
full, right-angle turn is reached. Unwanted edge diffractions would be created
by the sharp edges of such a mouth. Thus no provision is made for the reduction
of circular cross-section horns."

The formulas there looked to be valid and could probably be done in Excel/spreadsheet, but it still comes back to that fc and in the case of a midrange the wavelength is very short (800hz = .0013) so I would assume it needs to be multiples instead of fractional...or just tiny. Assumptions have a way of biting me back though~ @¿@ ...Thoughts?

The boring bar looks pretty good although those inserts don't seem to have a rake to them and may cause a bit of issue. Look forward to seeing how it works...think I might try it on something other than your part, first. ~¿@ Have you thought of maybe using a Graver to take off the tops of your steps? The depth may be a bit tricky to hold onto and need a rest to reach in there.