[TowerTalk] Adjustments to Tower Base Pier J-Bolts
scott.small at gmail.com
Sat Jul 22 14:13:24 EDT 2017
Use a cutting torch to segment your template; the kerf will provide enough
clearance for the first piece to move that 1/8", and then the rest would
have more room. Scribe match lines on either side before the cut, and then
you can weld them back together to spec once free. If you drop a wet rag on
each bolt before the cut you won't have to worry about heat affected zone
extending to the structural bolts. If needed use a die grinder to relieve
each hole in the base plate ~60 thou to prevent binding or distortion due
to differences in expansion when conditions change, then treat the ground
area before installation to prevent galvanic corrosion.
$.02 from a random spectator who hasn't tried it.
On Saturday, July 22, 2017, Paul Christensen <w9ac at arrl.net> wrote:
> Got a nasty situation here that needs some brain power to resolve. Earlier
> this year, I poured two base piers for a pair of Pirod self-supporting
> towers. The 140 ft. tower base has the problem. Unfortunately, the base
> J-bolts on two of the three equilateral triangle points are bent inward,
> toward the base center by 1/8". That 1/8" may not seem like much, but it
> is. In fact, the template used during the pour cannot be removed. During
> the pour, the J-bolts were double-nutted, one on top and the other below
> template. Still, the force of the concrete pour managed to push out the 6
> ft. J-bolts. As that was settling, I quickly moved the crew to the other
> tower as sunset was minutes away. I did not go back and take a level to
> bolts, thinking the template would keep them perfectly straight.
> Each 6 ft. bolt is exactly 1-7/8" in diameter. Each protrudes 12" above
> concrete surface. Moving these huge bolts even 1/8" will take a Herculean
> effort. The template holes are the exact same diameter and made that way
> minimize shift of the type that occurred anyway. The tower base section
> mounting holes that are exactly 2.0" in diameter. So, there's just a small
> amount of wiggle room. If we can get the template off, then I know that
> tower base will absolutely go on without trouble.
> Some options:
> 1) Use an oxy-acetylene torch and apply heat at the point where the J-bolts
> exit the base, then pound with a sledge hammer. Trying it now without heat
> is futile; we've tried and the bolts are going nowhere. I have no idea
> heating will do to the strength of the J-bolt.
> 2) Use a telescoping hydraulic cylinder (a.k.a. hydraulic ram jack) to
> the two J-bolts against each other since they are both leaning in by the
> same amount. What I don't know is how much adjusting precision I'll have
> when expanding the cylinder. Do these things move in very small
> What cannot occur is the cylinder "jerking" the bolts to anything beyond
> 1/8". These cylinders are capable of pushing 30,000 lbs. and are typically
> used on large earth-moving front loaders.
> I'm open to any other ideas.
> Paul, W9AC
> -----Original Message-----
> On Behalf Of Rudy
> Bakalov via TowerTalk
> Sent: Saturday, July 22, 2017 9:10 AM
> Subject: Re: [TowerTalk] 80 M 4 SQUARE MODELING
> I am in the exact same situation- 95' tower that I plan on using to suspend
> wire elements from the top of the tower.
> I assume THERE WILL BE interaction between the 4SQ and the tower. What I
> have been wondering is how mechanically reliable this setup is compared to
> elements made of aluminum tubing. Any thoughts on this?
> In addition, I have been wondering if the wire will stretch over time
> thereby changing the resonant frequency of the elements. Perhaps CAT5 might
> be a better option for the elements as it is less likely to stretch?
> Rudy N2WQ
> Sent using a tiny keyboard. Please excuse brevity, typos, or inappropriate
> > On Jul 22, 2017, at 8:43 AM, StellarCAT <rxdesign at ssvecnet.com
> > Now that I have finished my tower for 40-10 meters I need to start my
> project. I'm limited to the one 90 foot tower I have by county code. I am
> planning on running 4 ropes from the last guy point (84ft) to install a
> 4 square for 80 meters. Wires would be suspended vertically from the ropes
> in a typical 4 square pattern using Comtek switching.
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