Re: what's up with this?


[Follow Ups] [Post Followup] [Dodge Power Wagon Forum]


Posted by fletch on Friday, November 05, 2004 at 11:01AM :

In Reply to: what's up with this? posted by jim in n.y. on Thursday, November 04, 2004 at 7:26PM :

The fine thread gives a better mechanical advantage for holding. If you take the circumfrence and divide it by the pitch you get the mechanical advantage.
I quote from MET-2140 (12-79)

"If we started at the bottom and unwound one linear inch of thread, we would generate an inclined plane whose aproximate length would be the total length of the thread. If we consider one linear inch, the total thread length would be given approximately by the formula s= C x n
Where:
C = the circumfrence of the bolt
n = the number of threads per inch
s = the total length of the unwound thread

Since circumfrence is defined as C = pi D
Substituting, we can find s by:
s = pi Dn

We thus find the length of the thread for a bolt with a one inch diameter and 20 threads per inch as:
s = 3.14 x 1 x 20 threads/inch = 62.8"

The mechanical advantage is the ratio of the screw length to the distance traveled, or in this case:
MA = 62.8"/1"
MA = 62.8

end quote

compare that to a 1" 12 bolt that has an MA of 37.68

One reason it is so much easier to sheer off or strip out a fine thread than a coarse thread.

My .02



Follow Ups:



Post a Followup

Name:
E-Mail:
Subject:
Message:
Optional Link
URL:
Title:
Optional Image Link
URL:


This board is powered by the Mr. Fong Device from Cyberarmy.com