I highly recommend the DX Engineering stuff... it is the olde Al Harbach
stuff which I have used for years... the cast saddles are one of a kind
and make for a significant amount of surface contact of the tube versus
a common "muffler-type" saddle which is formed sheet metal and is a very
narrow pair of edges that touch the tubing.
As far as custom sized stuff - go to any major bolt house in your area -
they will have someone who makes their custom stuff...
Here in FL several years ago the Florida Contest Group got together a 2"
u-bolt order... we ordered hundreds of 2" u-bolts, 5/16" stock - had
them made with 2 1/16" leg spacing so they could be squeezed down a
little for 2" or spread up a little for 2 1/8" applications (can you say
Cushcraft?)... they also worked great on Tailtwisters... bottom line was
they were custom made but because of the quantity involved they ended up
being cheaper than 2" galvanized u-bolts at a hardware store....
Look in the yellow pages for Fasteners - Wholesale and request some
bids. I usually ask for their fax number and then send the same fax to
a bunch of places when bidding... "please quote on the following"
As far as stainless being softer, yes it is... I live in Tampa Florida -
it is inland but plated hardware starts to rust here in about two weeks
of exposure to the humidity... as a result all of the yagis I build are
100 per cent stainless steel... you have to learn what you can do with
SS - it is very easy to gall the threads and ruin a u-bolt - do not lay
on the ratchet when tightening like you may be used to with a steel
bolt! Once galled a stainless bolt has to be broken - at that point you
just keep twisting until "snap" it is broken... if you are worried
about holding power perhaps you would want to increase the number of
bolts so each shares the load - that is probably what you are seeing
with the spec change you are being quoted.
I am helping with some antenna and tower removal for a silent key here
in FL, the bolts on the towers are so rusted it has been necessary to
"fall" the towers... quite a sight seeing a 120 footer comin down - talk
about your mixed emotions!
If you are taking this stuff on an expedition or are going to be in a
humid environment - I recommend the stainless... some say go with grade
7 bolts but I have seen those rust, too... I recommend you read
W6QHS/W6NL's book regarding stainless steel hardware and yagi
construction. If you have not read it - buy a copy - it is a must for
your bookshelf - a copy of it just sold on eBay
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3034496624&category=15050&rd=1
Buy it, you'll like it!
73,
Jim, K4OJ
kk9a@arrl.net wrote:
> I am currently building several antennas which will be installed in a
> corrosive environment and I'm looking for bolts to clamp the boom to the
> mast. DX Engineering sells SS "U" bolts along with an aluminum saddle. I
> normally use 4 mast and 4 boom clamps when using 3/8 dia steel "U" bolts,
> however DX Engineering seems to recommend 8 boom and 5 mast clamps when
> using their 5/16 dia "U" bolts. I believe that stainless steel has less
> tensile strength than steel and also using a reduced diameter concerns me.
> Are there any better sources SS "U" bolts that fit 2 1/2" and 3" O.D.
> tubing. I'd also like to hear comments from anyone using the DX Engineering
> bolts.
>
> 73,
> John
>
> _______________________________________________
>
> 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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