ile-width="520" data-file-height="477" /></a>
<div class="thumbcaption">
<div class="magnify"><a href="//en.wikipedia.org/wiki/File:Whitworth.jpg" class="internal" title="Enlarge"><img src="//bits.wikimedia.org/static-1.24wmf7/skins/common/images/magnify-clip.png" width="15" height="11" alt="" /></a></div>
Whitworth thread form</div>
</div>
</div>
<p>The form of a Whitworth thread is based on a fundamental triangle with an angle of 55° at each peak and valley. The sides are at a flank angle of <i>Θ</i> = 