spridgets
[Top] [All Lists]

Re: Taps dies etc. v.2

To: Ajhsys@aol.com, mgagne@unc.edu, spridgets@autox.team.net
Subject: Re: Taps dies etc. v.2
Date: Mon, 24 Sep 2001 18:52:07 EDT
In a message dated 9/24/2001 9:33:59 AM Eastern Daylight Time, Ajhsys@aol.com 
writes:


> I use grade 5 when replacing grade 5 and sometimes when replacing hardware 
> grade bolts.  Using grade 8 can cause some problems because grade 8 is more 
> brittle.  It should only be used where it is needed.
> 

We have had quite a discussion about this on several occasions on the list.  
Generally I agree with Alan, but there is a consideration that makes me think 
replacing with Grade 8 is sound.  While the Grade 8 is more brittle, as in 
not as flexible and "stretchy" as the Grade 5, the brittleness does not  
become a factor until well after the grade 5 bolt has stretched and groaned 
and broken.  For instance, a Grade 5- 7/16" Fine thread bolt has a proof load 
of 10,100 lbs. and a tensile strength of 14, 240 lb.  A Grade 8-7/16" Fine 
thread bolt has a proof load of 14,250 lb.(equal to the TENSILE strength of 
the Grade 5) and a Tensile strength of 17,800 lb.  So while the Grade 5 
fastener is stretching to its tensile strength of 14,240 lb. the Grade 8 is 
just getting started.

There IS a happy compromise: The Bowmalloy bolt, produced by Bowman, 
headquartered in Cleveland (1-800-726-9626).  The Bowmalloy 7/16" Fine thread 
bolt has a proof load of 18,520 lb and a Tensile strength of 21, 370 lb.  No 
financial interest, and I have never used the Bowmalloy, but I have seen it 
demonstrated and it ranks well above a standard Grade 5 or 8.  I am NOT an 
engineer, just know what I saw.  The engineers on the list may be able to add 
something to this.

Stainless is out of the question unless it is not a load bearing bolt.  
Holding wings on, etc., they are great.

--David C.



<Prev in Thread] Current Thread [Next in Thread>