On Friday 07 September 2007, Chris Radek wrote:
>On Fri, Sep 07, 2007 at 11:10:13AM -0400, Gene Heskett wrote:
>> Greetings all;
>>
>> Is there documented someplace where I can grab a copy and print it, a
>> method to calculate the major and minor diameters of a thread that is
>> specified only as 16 tpi, pitch diameter 0.965"?
>
>If the pitch is .0625, the height of the triangular thread (sharp
>minor to sharp major diameters) is .0625 * sqrt(3)/2 = .054.
>
>The pitch diameter is halfway between the sharp minor and sharp
>major diameters, so minor is .965 - .054/2 and major is .965 +
>.054/2
>
>This gives .938 and .992 as the sharp diameters.
>
>> I got out my calculator and came up with a figure of 0.926" for the minor,
>> but when I quit boring at 0.917 last night and switched to the single
>> tooth threading bar I'd made, the nut fit the threads while they were well
>> under 50% cut! Very sloppily too.
>>
>> So when I turned it around to do the other end, I measured the nuts
>> exterior threads
using the knife edges of my digital caliper, which aren't that sharp and do
not appear to make it all the way to the gullet of the thread.
>> and came up with about 0.878" so I bored that end to
>> about 0.865" and started threading. This end fit better, but wasn't even
>> close to having sharp inner peaks yet because the starting diameter was
>> still too big, leaving a very noticeable flat.
>
>These numbers don't work out to match mine... Something funny is
>going on.
Kinda what I thought too, Chris. The threads in question are the threads on
the exterior of those 1/2" 10 TPI bronze nuts that McMaster-Carr sells for
way too much $, which are listed as having a 16 tpi thread whose pitch
diameter is 0.965".
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Appendix:
A portion of a book, for which nobody yet has discovered any use.
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