At 11:36 AM 2/22/2005, you wrote:
>Hi, John --
>
> Good engineering points. I am going by the advice of PE Hank, KR7X, who
>advised me of that. He pointed out that the typical allthread is the same
>material as the US Towers J-bolts. I'm 99% sure that's what he told me. I
>suppose I
>could be wrong.
Steve--
Can't speak for any other tower company. Almost all of my experience
is with Rohn stuff. And I have a 140 ft SSV that I hope to get up now
that I have moved to TX.
But the All-thread I have seen is pretty cheap stuff, nothing more than the
lowest grade hardware-store bolts. Although I have seen stainless steel
All-Thread advertised.
> I don't remember if the original poster said what kind of tower it was
>for, probably some ham application that won't be anywhere near the stresses
>needed for failure.
The original poster was inquiring about an SSV tower, which is why I went
to those drawings.
> How about this? I have ordered anchor bolts for Trylon towers and they
>sent me lengths of REBAR with rebar nuts. Very coarse threads and
>questionable
>strength IMO. I used the rebar but had the nuts welded on since I didn't want
>them loosening up. I would much prefer allthread in this case.
Don't know what Trylon uses and I have to ASSUME that they know
what they are doing. The liability issue without a PE stamp seems
pretty serious.
> I guess my point was that there are more options when it comes to the
>anchor bolts, especially the bottom end - nuts instead of bent in a "J".
I once knew a guy who always insisted that you should do what the
manufacturer says to do. The inquiry was for SSV and the Rohn SSV
drawings I have specify A325 quality. And the tensile numbers come
from the ASTM spec. So when in doubt, do what the manufacturer
says! ;-) (Right, Steve??)
Rohn DOES charge an arm and a leg for their J-bolts. But any decent
sized city has a bolt manufacturer that can make J-bolts and meet the
A325 spec. The A325 spec is what is used in any serious steel construction
like bridges and buildings. I would check under fasteners and call the
company
with the biggest ad in the yellow pages. If they can't do it they will
know where
to get it done. When I last inquired about having some J-bolts made for
me I found that having them custom made was cheaper than Rohn. But
that was a number of years ago. Then there is the issue of galvanizing them.
The bolt manufacturer can handle all of that. Just don't expect them
overnight.
Some of Rohn's prices are "convenience store" prices. Such as on their
tools and their tower paint. I once took the Rohn spec for white and
orange paint to a paint dealer and he said he could meet the same
spec and would charge the same price as Rohn, but for FIVE gallons
rather than for ONE gallon. I once bought a 100 ft self-supporting tower
with no bolts. Buying the needed A325 bolts from Rohn cost me more
than the tower itself!
73 -- John W0UN
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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