Threads and Threading - Sportpilot.info
Threads and Threading - Sportpilot.info
Threads and Threading - Sportpilot.info
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
ANSI BUTTRESS THREADS 1853<br />
Table 3. American National St<strong>and</strong>ard Buttress Inch Screw Thread<br />
Symbols <strong>and</strong> Form<br />
Thread Element Max. Material (Basic) Min. Material<br />
Pitch p<br />
Height of sharp-V thread H = 0.89064p<br />
Basic height of thread engagement h = 0.6p<br />
Root radius (theoretical)(see footnote a ) r = 0.07141p Min. r = 0.0357p<br />
Root truncation s = 0.0826p Min. s = 0.5; Max. s = 0.0413p<br />
Root truncation for flat root form s = 0.0826p Min. s = 0.5; Max. s = 0.0413p<br />
Flat width for flat root form S = 0.0928p Min. S = 0.0464p<br />
Allowance G (see text)<br />
Height of thread engagement h e = h − 0.5G Min. h e = Max. h e − [0.5 tol. on major<br />
dia. external thread + 0.5 tol.<br />
on minor dia. internal thread].<br />
Crest truncation f = 0.14532p<br />
Crest width F = 0.16316p<br />
Major diameter D<br />
Major diameter of internal thread D n = D + 0.12542p Max. D n = Max. pitch dia.of internal<br />
thread + 0.80803p<br />
Major diameter of external thread D s = D − G Min. D s = D − G − D tol.<br />
Pitch diameter E<br />
Pitch diameter of internal thread<br />
(see footnote b )<br />
Pitch diameter of external thread<br />
(see footnote c )<br />
Minor diameter K<br />
E n = D − h Max. E n = D − h + PD tol.<br />
E s = D − h − G Min. E s = D − h − G − PD tol.<br />
Minor diameter of external thread K s = D − 1.32542p − G Min. K s = Min. pitch dia. of external<br />
thread − 0.80803p<br />
Minor diameter of internal thread K n = D − 2h Min. K n = D − 2h + K tol.<br />
Height of thread of internal thread h n = 0.66271p<br />
Height of thread ofexternal thread h s = 0.66271p<br />
Pitch diameter increment for lead ∆El<br />
Pitch diameter increment<br />
for 45° clearance flank angle<br />
Pitch diameter increment for 7° load<br />
flank angle<br />
Length of engagement L e<br />
Machinery's H<strong>and</strong>book 27th Edition<br />
∆Eα 1<br />
∆Eα 2<br />
a Unless the flat root form is specified, the rounded root form of the external <strong>and</strong> internal thread shall<br />
be a continuous, smoothly blended curve within the zone defined by 0.07141p maximum to 0.0357p<br />
minimum radius. The resulting curve shall have no reversals or sudden angular variations, <strong>and</strong> shall be<br />
tangent to the flanks of the thread. There is, in practice, almost no chance that the rounded thread form<br />
will be achieved strictly as basically specified, that is, as a true radius.<br />
b The pitch diameter X tolerances for GO <strong>and</strong> NOT GO threaded plug gages are applied to the internal<br />
product limits for E n <strong>and</strong> Max. E n .<br />
c The pitch diameter W tolerances for GO <strong>and</strong> NOT GO threaded setting plug gages are applied to the<br />
external product limits for E s <strong>and</strong> Min. E s.<br />
Copyright 2004, Industrial Press, Inc., New York, NY