Search results
Results from the WOW.Com Content Network
The thread form is slightly modified to increase the minor diameter, and thus the strength of screws and taps. The major diameter still extends to within 1 / 8 H of the theoretical sharp V, but the total depth of the thread is reduced 4% from 5 / 8 H = 5 / 8 cos(30°) P ≈ 0.541P to 0.52P. [5]
Example (inch, fine): For 7 ⁄ 16-20 (same diameter as the previous example, but this time with 20 threads per inch, which is considered fine), 0.437 in × 0.90 = 0.393 in (i.e., if the threads are to be fine, then a slightly larger diameter drill bit should be used before tapping the hole for the screw).
The taper rate for all NPT threads is 1 inch of diameter in 16 inches of length (3 ... 16 8 0.12500000 3.1750 1.8120: 14.50: 15.87575 2.4500: 19.60: 15.91563 2.8837
The thread depth is 0.54125 × pitch. The outermost 1 ⁄ 8 and the innermost 1 ⁄ 4 of the height H of the V-shape are cut off from the profile. The relationship between the height H and the pitch P is found using the following equation where θ is half the included angle of the thread, in this case 30°: [ 3 ]
This thread form also allows for the use of a split nut, which can compensate for nut wear. [8] The line of General Purpose (GP) Acme threads (ASME/ANSI B1.5-1997) are not designed to sustain external radial loads and both the nut and bolt are, ideally, independently supported (the nut by a linear guide and the screw by shaft bearings).
A rule of thumb is that the undercut should be at least 1.5 threads long and the diameter should be at least 0.015 in (0.38 mm) smaller than the minor diameter of the thread. [1] Strictly speaking the relief simply needs to be equal or slightly smaller than the minor diameter of the thread.
Ecological threshold is the point at which a relatively small change or disturbance in external conditions causes a rapid change in an ecosystem.When an ecological threshold has been passed, the ecosystem may no longer be able to return to its state by means of its inherent resilience.
Main page; Contents; Current events; Random article; About Wikipedia; Contact us; Pages for logged out editors learn more