Steve,
Let us know your custom HDG u-bolt source. Portland Bolt makes them but
only 1/2" and up.
While I use the excellent DX Eng stainless u-bolts with the cast
saddles, I also use hot dip galvanized u-bolts without saddles, but
internally sleeve at the bolts. Long sizes are available from McMaster
when thicker plates are used. (unfortunately, long are always too long
(aesthetics not function) and standard too short). SS always needs TLC
to not gall which can be a real PITA when it happens. As mentioned,
taking them apart after a few years can be difficult.
An antenna I have in construction has all elements insulated with Stauff
clamps to hold the elements to the boom plates. Available from DXE,
McM, ebay, and others. For large diameters I make my own split
insulators with 3/8 thru bolts out of 1" thick (or thicker) UV resistant
nylon (or other UV resistant plastic). These can be bored in a garage
lathe 4 jaw chuck, small mill with a rotary table, or CNC, drilled and
then and split on a bandsaw or table saw. I use 3/8 thick 6061 plates
on top. I had to replace split ABS pipe used as an insulator on one
commercial antenna. ABS pipe is a very poor choice since it is foam
core and compresses over time. Most cast solid UV resistant plastics
are ok at HF. Center of element voltages are low and dissipation losses
are minor.
Bent saddles (muffler clamps) get loose as the saddle splays out or
deform the boom/element when tightened, so avoid them.
Another trick is to internally sleeve where a boom or element is
clamped. One size or two of telescoping tubing. A damaged section can
be cut out and two sleeves extended both sides plus the replacement
center diameter. Sometimes sleeves can be driven into lightly damaged
sections with lots of Penetrox, a wood plate, and mallet. Taper the edge.
Grant KZ1W
On 6/30/2017 6:40 AM, Steve NR4M wrote:
Hello Gary,
Good luck on finding something.
Years ago, I was not happy with my choices. I just can not see paying
~$15 for a SS U-bolt and 'part-the-way-around' saddle. Don't know the
alloy of the SS material, but you can bet it's not the best stuff out
there.
But, what really gripes me is because of the high coefficient of
adhesion, stainless galls and seizes sooo easily. If I really NEED to
use SS, I consider it a 'one use' item.. I have not found a anti
seize compound that works well enough, or LONG ENOUGH, to alleviate
this problem.
All may be fine now, but try and take the U-bolt apart in 5 years.
Doesn't help you, but my solution was to have custom U-bolts made in
quantity, in several sizes, with a hot dipped galvanized coating.
Never had one fail; never had one gall. I found a place in FL that
makes what I want.
For saddles, I make my own from billet 6061-T6 aluminum 3/4 of an inch
thick, and just shy of a half circle. These things hold super tight.
Fortunate to be a retired machinist and have a Bridgeport milling
machine. Wish I had a CNC machine, but not too bad doing 50 at a time.
Good luck.
73 de Steve, NR4M
On 6/29/2017 22:53, Gary Schafer wrote:
I am looking for some 2" and 3" saddle clamps (muffler clamps) to
replace
all the boom to element plate clamps on the 40 meter beam.
What is the best type, galvanized, zinc plated or just plain steel?
Also where do you guys buy them?
Thanks
Gary K4FMX
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