I’d add a couple more comments:  Choice of wood stock is critical. Straight
grain, knot free, stable hard wood without much difference in hardness
between summer and winter wood (uniform grain) is what you are looking for
(beech, hard maple, elm,  persimmon, fruit woods like apple, pear).  Making
internal threads is usually more successful (easier) than cutting the
external threads (which sometimes peel off /split off in some sections
because of weak side grain).
  The difficulty in cutting threads increases exponentially with increasing
OR decreasing size with ⅝” to  ¾” threads being relatively easiest with
this method).  Most of the old die stocks that I have found in the wild
were about this size, used for making the luthier clamps (two wooden
threaded disks threaded onto a dowel used for gluing up violins and
guitars), or wooden threaded clamps similar to the Jorgensen style wooden
hand screws) or various side-arm  planes.
  If you are looking to make 2” diameter screw threads for a leg clamp or a
cider press, this method doesn’t really work very well for that.  St Roy
has a couple of articles on how to make a screw box in one of his books as
well as in an episode of his PBS show (that you might be able to find and
watch free online).  He also shows methods for cutting the big 1 or 2 tpi
screws used for huge screws used in eg. communal cider/wine  presses in one
of his books.
Cheers from Waterloo

Claudio


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