[TowerTalk] 80m vertical ideas / questions

[Grant Saviers]

UHDPE likely doesn't have the strength and it does creep besides. 
<4000psi yield strength.

Fiberglass maybe is a better bet. However, there are two kinds or rod, 
pultruded where the fibers are axially aligned and extruded with the 
resin and concentrically wound woven glass fabric that is resin infused.

With the thru bolts from the legs exerting pull or push forces, the 
pultruded version has low tear out resistance.

The "garolite" G10/FR4 rods from McMaster are the fabric version.
35,000 to 50,000psi tensile strength, probably 20% less yield although 
composite materials don't behave like steel. Common hot rolled steel has 
similar tensile strength.

At a minimum, the cross section reduction from the bolts needs to be 
considered in any analysis.  Some calcs needed before going forward!

Rohn specifies a tight fit of the leg bolts and I think that is needed 
for inserted rods, which implies a good setup and technique for drilling 
the rod holes.  Plus the rod needs turned to two diameters.  All work 
for carbide tooling, PPE, and good dust collection.

I need a set so will be looking harder at the issues.  Woven kevlar 
epoxy solid rods would even be better if they exist.  Anbody know of a 
source?

Grant KZ1W



On 12/31/2021 11:24, Bill Coleman wrote:
> Perhaps UHDPE plastic cylinders would do as well as fiberglass?
> 
>> On Dec 31, 2021, at 6:52 AM, Rob Atkinson <ranchorobbo at gmail.com> wrote:
>>
>> If your vertical is
>> out in the open on flat land and you have a wind storm, it will
>> destroy plastic leg insulators and the ceramic ones hams find aren't
>> made for this.  Not sure about the fiberglass cylinders that fit
>> inside the legs.   Maybe they are more robust.
> 
> Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
> Web: http://boringhamradiopart.blogspot.com
> Quote: "Not within a thousand years will man ever fly!"
>             -- Wilbur Wright, 1901
> 
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