My choice would be likely the grade 5 bolts, a good compromise between
strength and brittleness. Gr 8 is very strong but in some cases will fail
where a Gr 5 won't - I routinely lost 1/2 inch Gr 8's in a pinned mast
(using 2 of them) turning a large log periodic and replaced with Gr 5 and
they have lasted 5 years or so. They may be slightly deformed at the shear
pressure points but they don't break clean like the Gr 8 ones did.
73 Don
VE6JY is Don Moman email: ve6jy@freenet.edmonton.ab.ca
Box 127 Lamont, Alberta
T0B 2R0 (403) 895-2925
On Thu, 9 Oct 1997, Ron Majewski wrote:
>
> Hello to all-
>
> I'm installing a roof tower on my house and have a question about
> bolt grades. My local hardware store sells grade 3, 5, and 8 bolts.
> The tower loading will place some bolts under tension, while others
> will be under shear. The manufacturer makes no recommendation as to
> bolt grade.
>
> Are there any rules for choosing bolt grades given a specific load
> situation?
>
> Thanks in advance and 73,
>
> Ron (W8RU).
> majewski@erim-int.com
>
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