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Re: [TowerTalk] Saddle clamps (muffler clamps)

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Saddle clamps (muffler clamps)
From: Steve Bookout <steve@nr4m.com>
Date: Fri, 30 Jun 2017 15:13:51 -0400
List-post: <mailto:towertalk@contesting.com>
Hi Grant,

The place is called Bolt and Nut, inc  http://www.boltandnut.com/

They can make anything you want.

About a year ago, I was running out of 3 inch U-bolts, so I bought another 150. Frank, W3LPL, went in with me and got 150 and we were able to get a better price.

They don't do the galvanizing in-house, so it takes a bit longer to get them. I guess it was 4 to 6 weeks or so. Also, supplied galvanized nuts.

I'm going to order some more 2 inch U-bolts in the next couple of weeks, if anyone wants some. I won't know the exact price till I give them the quantity.

Steve



On 6/30/2017 11:52:AM, Grant Saviers wrote:
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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