I am using 3/4" grade 5 (F593C) stainless bolts on my Delhi HD and
wondered if anyone has a torque spec for these in this application?
Looking at the Taco/Delhi installation sheet I see they have specified a
star type lock washer. I've used the split compression type and am
wondering if they should be replaced? In several instances I can turn
the entire nut/bolt assembly on the leg with the big torque wrench and
in those cases I can see the washer is fully compressed however for some
reason there is a slight gap between the two ends of the washer when
compressed. The ones that are rock solid tight have a nice tight
compression to the lock washer without any gap showing.
Kirb - VE6IV
--
Jim Thomson wrote:
> Date: Sat, 08 May 2010 14:07:22 -0700
> From: Kevin Normoyle <knormoyle@surfnetusa.com>
> Subject: [TowerTalk] Taco DMX install instructions (same as Delhi)
>
> I was curious and found this.
>
> Taco sells the same tower that Wade did as Delhi
> The install instructions for Taco DMX are here
>
> http://www.tvantenna.com/products/tvreception/mounting/towers/taco/dmx/DMXinstructions.pdf
>
> They show bolts facing in, with a single washer at the nut, (not split
> lock washer, a star lock washer with internal teeth.
> They say "All bolts and nuts are specially heat treated"
>
> ## On Delhi towers... the bolt heads are in the outside.. and
> nuts are on the inside. Same deal with Tryon. On my old LORD
> tower.. 32" wide x 20' straight sections, they used 10 x 3/8" bolts
> to splice each leg, 3 in the flat corner, and 4 on each side. They did
> not stagger the hole pattern, so the nuts have to go on the outside.
>
> ## Trylon staggers the hole pattern... so nuts can go on the inside.
> 2 on one side of V legs is a little higher than the other side. In the case
> of a Delhi, it makes no difference if nuts are on inside, or outside. If u
> put
> the nuts on the outside, you have mote chances of getting stuff like coax,
> rope, etc, etc, hung up on the nuts and any excess threads.
>
>
>
>
> and "These special heat treated bolts have solid shoulders in order to
> prevent the tower sections from shifting. Tighten the nut securely, but
> be careful not to strip the threads".
>
> If the nuts and bolts are heat treated, they must be at least grade 5?
> Doesn't say if galvanized.
>
> ## it doesn't really say anything. Why not jus quote either a SAE G5/8
> spec.. or an ASTM spec.... then you can relate to it. If you can tighten
> up till you strip the threads on a 1/2" bolt.. look out. Any SAE-G5 bolt
> or A-325 bolt uses 94 ft lbs for a galvanized bolt... and 39 ft lbs on a
> 3/8" bolt.
>
> ## I use internal star washers on SS machine screws. We used em also at work
> on 1/2" bolts [cap screws] for inside iron work. Zero vibration though. On
> these traffic
> lights and tall lighting tubes... they all use galvanized split ring
> lockwashers....
> OR what appears to be a form of galvanized nylock. The galvanized nylocks
> used on US Tower corp pulley's don't budge. Trylon uses galvanized split
> ring lockwashers on all it's lower 5/8" G-5 leg bolts. My trylon was
> installed
> back in 1998.. and they are all still tight..checked over the last 2 x days
> with the
> new 2' long torque wrench.
>
> ## Apparently, on the latest eia-222 REV G spec... it sez some where abt
> the
> only bolt allowed on new tower installs has to be a A-325 bolt... and one
> that uses
> a special captivated nut.... that also tells you how much toque has been
> applied.
> [torque indicating flat washers] They called em... 'self locking nuts'.
> They also say that if any of the bolts are removed for what ever reason, the
> entire bolt,
> nut assy, etc has to be tossed away.. and can't be re-used. If you look
> at power co
> transmission towers that were put up yrs ago, they all used either G-5 [G-8
> in some places]
> or A-325 bolts and split ring lockwashers. You never see any of those things
> falling apart.
>
> ## when I dismantled the 600+ bolts in my old 30" wide L+R tower.. that was
> a gov
> install surplus tower... the bolts used had no marking on the heads.. and 99%
> were rusted.
> I could shear the shanks/threads with just a 1/2" socket wrench... so they
> were no more
> than G-2 mild steel. I replaced 600 of em with galvanized G-5 bolts I
> purchased from
> L+R. [ all 3x/8"... used for leg splices and also angle bracing.] I
> lubricated the galvanized
> bolts.. and quickly found that you could not put 40 ft lbs of torque on
> em... maybe 2/3 that.
> What happens if excess torque applied, and galv bolts lubricated beforehand
> is this. The nut
> would spin free ! Take the nut off... and it looked like you drilled it out
> with a 1/2" drill bit.
> The mating bolt had no threads.. all smooth ! What had happened is the
> threads had come off
> the nut and wrapped around the threads of the bolt... and ALL in one
> continuous piece.
>
>
> ## did you check the other bolts on your delhi ??? Were any of them loose
> ?? You
> may have just missed tightening the pair that fell out. What baffles me
> is... the delhi
> uses a 4" overlap on the legs [4.5" on a trylon] with the legs of the
> upper section
> on the INSIDE of the lower section. For your tower to fall over.. with no
> bolts... the
> bottom of the upper section legs [4" portion] would have to pop right
> out..which is
> extremely difficult. One guy here in town 'forgot' to tighten the 2 x
> bolts at the 40'
> level of his 48' delhi.. [ one leg only].. and one bolt fell right out. Both
> nuts gone..
> and 2nd bolt almost ready to fall out. The top section and F-12 5ba yagi
> leaned
> towards the section minus the bolt... not away from it..as yours did. With
> NO bolts
> the upper leg should have slid down the top of the section below it...
> resulting in
> a bigger overlap of sections.
>
> ## Check your top section out. Several delhi's here in town had loose rivets
> in the
> top 4' . I punched em out, then drilled em out to 1/4"...and replaced with
> 1/2-20
> G5/8 galvanized bolts. I had 72' of delhi up at my folks place between
> 1976-1979.
> Consisted of normal sections 9-8-6, then #5 straights up to the 64' level..
> then I turned the
> #4 section, into a top section, with new thick AL plates, and custom
> machined right angle
> tabs in the corners. 2 x thrust bearing used...and Prop pitch sat down 10'
> down inside the
> tower. 12 x guy wires too.... 4 x per level...and 3 x levels of guys. The
> top 16' of tower
> still twisted ! [ 2 x big yagi's on mast] I gave up on delhi's after that,
> imo, they are just
> not strong enough. The original 64' delhi was designed for deep fringe TV
> ants.. that's it.
> later on, they came out with the #4 + #5 straight sections. BX tower's in
> the USA are
> very similar design.. and they now say, no booms longer than 10'... I can see
> why.
>
> ## IF they are carefully guyed.. like with a 6 x guy, star of david, monster
> cue-rack
> setup, it will be ok.
>
> Later... Jim VE7RF
>
>
>
>
>
> 1/2" diameter x 3/4" bolts on bottom sections. 3/8" x 5/8" for upper
> sections
>
>
>
>
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>
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