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Most lathes have two,some worn by mere turning.
Others endure endless trips of carriage pushing chips whilst cutting internal threads.
Pssh-shaw! Maybe OK in a captive shop, job shops have to compete.
Our own Dr.Al [discipline of practice unknown] posted an outstanding means he built for tap & die management with storage and instant retrievibility, retrievebility, retrieveability Bite me, spell check That bought out my compliments for all of the design, completion, and presentation.
Which then cascaded into a lengthy but accurate hack of his thread, naturally. As a confessed thread-hacker (often about threading oddly enough) seemed expedient to r-u-n-n o-f-t and post that content independently.
Therefore, herewith and with out further delay.........[*]
There are ACME taps with a double cut arrangement, presents roughing portion ahead including a long tapered lead section, due proportional mass of material removal creating a full thread, so concept not completely foreign. That length and waist make smaller ones feel fragile, multiplied by higher cost.
BTW, when facing any quantity of internal ACME threads, here is a lathe trick. Single point the pitch and thread profile anywhere from 10%-80% less than full, then run the tap. If evaluating fit, a sample 3 diameters long will be reliable substitute for an actual ($$!!) gauge. The actual trick now, having run the single point before hand, is sync'ed to shave least possible remaining material for actual finish.
Works on V-threads too, especially when expecting to finish with a big ol' coarse tap and 3' wrench...
Our practice modified this a bit farther, making bronze nuts for lead screws. New taps went by way of toolroom first, mounted between centers on cutter grinder to remove a bit of the OD, depending on size, ~ +/-less than 15%. Now a roughing tool, saved untold hours repeatedly poking a bar in there for chips following the lathe's lead screw. The logic reduced ensuing wear of machine overall, concentrated on half nut and screw.
Of all things personal computing had promised, (yes microsoft, apple, print cartridge designers, I-phone, android....Bite me again, you too spell check many of those failed to materialize; such as reducing consumption of trees for paper, streamlining administration, or being that great equalizer of sought information and random knowledge.
[*] One was never promoted that reigns supreme......all hail copy/ paste
On a roll now, itching to drop something at Shop Truths, Phrases, Tales; and Outright Lies as well!
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