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Gazing up at my Wellbrook ALA 1530 loop which has served me well as one of my receive solutions I noticed a slight tilt from the vertical. On further examination I found that the clamps that secure the mounting spigot to the TV type rotator had loosened (even with star washers). In addition the two long screws that secure the amplifier and loop to the mounting flange were also loose. I am reluctant to pull those screws up very tight as they go through the plastic housing and may damage it it some way.
It may be worth checking your own installation, I can only assume vibration from the strong winds here on the Kent coast have caused this problem. I always turn the loop to reduce action of prevailing winds.
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G0JFS? Wrote
?
<Gazing up
at my Wellbrook ALA 1530 loop which has served me well as one of my receive
solutions I noticed a slight tilt from the vertical. On further examination I
found that the clamps that secure the mounting spigot to the TV type rotator had
loosened (even with star washers). In addition the two long screws that secure
the amplifier and loop to the mounting flange were also loose. I am reluctant to
pull those screws up very tight as they go through the plastic housing and may
damage it it some way.
It may be worth checking your own installation, I
can only assume vibration from the strong winds here on the Kent coast have
caused this problem. I always turn the loop to reduce action of prevailing
winds. >
The
screws can be tightened so that there is little free play on the assembly
without causing any damage.
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Hi,
I work in avionics and deal with vibration related problems. Three
suggestions suggestions wrt to dealing with hardware working loose.
You could keep the plain nut and star washer hardware but use (blue,
as it is removable) locktight on the threads, alternatively replace the
nuts and star washers with fibre lock nuts and flat washers. The
third, and likely most affordable method is to use jam nuts
( ) .There are other ways (pal
nuts but you
may find a good quality fibre lock nut, or nuts to use as jam nuts, in
a local hardware store.
Ron VE8RT
On Sun, 02 Jan 2022 05:10:22 -0800
"Oyster Town (G0IFS) via groups.io"
<nigel_clayton@...> wrote:
toggle quoted message
Show quoted text
Gazing up at my Wellbrook ALA 1530 loop which has served me well as one of my receive solutions I noticed a slight tilt from the vertical. On further examination I found that the clamps that secure the mounting spigot to the TV type rotator had loosened (even with star washers). In addition the two long screws that secure the amplifier and loop to the mounting flange were also loose. I am reluctant to pull those screws up very tight as they go through the plastic housing and may damage it it some way.
It may be worth checking your own installation, I can only assume vibration from the strong winds here on the Kent coast have caused this problem. I always turn the loop to reduce action of prevailing winds.
--
Ron VE8RT <ve8rt@...>
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Thank you Andrew, I feel happier about pulling them up tighter.
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Thank you Ron, good suggestions to be employed when the weather calms down!
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Did everyone notice that the one thing Ron did not mention was split-ring "lock" washers?
That's because they are worse than no lock washer at all when it comes to being the only thing used to prevent loosening.
From a NASA study:
“The? typical? helical? spring? washer? …serves as? a? spring? while? the? bolt? is? being? tightened.? However,? the? washer? is? normally? flat? by? the? time? the? bolt? is? fully? torqued.? ?At? this? time? it? is equivalent? to? a? solid? flat? washer,? and? its? locking? ability? is? nonexistent.? ?In? summary,? a lockwasher? of? this? type? is? useless? for? locking.”
I've gotten in arguments with engineers over this, and sadly they continue to be used where they serve no purpose.
If, =if= you use another method to lock the parts in place, for instance the fiber locking nuts Ron mentions, a split ring washer can act like a spring and keep things a little more snug if the parts become loose, but temperature change or a stretched bolt is the only reasonable situation I can picture that being an issue. Everything I work on has a split ring washer on top of a regular washer, and blue Loctite on the threads. In that case, they are there purely to prevent the device from vibrating excessively due to temperature caused temporary loosening. The fact that every single commercial product I've seen has the lock washer on top of a regular washer proves that it is NOT providing a locking function by digging into the surface.
Absent any other method to lock the parts in place, split-ring lockwashers can actually hasten loosening under vibration and temperature changes. See the graph on the last page in the PDF I linked to below.
Let's see if I can link to the PDF:
http://hillcountryengineering.com/wp-content/uploads/2011/10/Split-Lockwashers-Separating-Myth-from-Truth.pdf
Sadly, there are a lot, a LOT of websites, mechanics, and even mechanical engineers giving out bad advice about split-ring lockwashers.
--
Steve Greenfield AE7HD
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Hi,
I understand that :-) yesterday around this time it was -42 C with
a wind chill of -54 C. Other than going out to take a few photos and
to clear the build up of ice on the furnace and water heater exhausts,
I wasn't up to any other work. Its warmed up today, currently we're at
-31 C with snow, with an overnight forecast low of -41C
With the alternatives I've listed you do not rely on compressing a
lock washer, reducing the risk of crushing what you've mounted, and
where there may be allowance for thermal expansion and contration (+30C
extreme max in summer to -45C extreme minimum in winter).
Ron VE8RT
On Sun, 02 Jan 2022 07:23:56 -0800
"Oyster Town (G0IFS) via groups.io"
<nigel_clayton@...> wrote:
toggle quoted message
Show quoted text
Thank you Ron, good suggestions to be employed when the weather calms down!
--
Ron VE8RT <ve8rt@...>
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Greetings
Once you tighten things up, how about running another nut against the nut holding everything in place. Tighten it it so it jams against the original nut.
Dick/W7wkr. CN97uj
toggle quoted message
Show quoted text
On Jan 2, 2022, at 7:48 AM, Ron VE8RT <ve8rt@...> wrote:
Hi,
I understand that :-) yesterday around this time it was -42 C with
a wind chill of -54 C. Other than going out to take a few photos and
to clear the build up of ice on the furnace and water heater exhausts,
I wasn't up to any other work. Its warmed up today, currently we're at
-31 C with snow, with an overnight forecast low of -41C
With the alternatives I've listed you do not rely on compressing a
lock washer, reducing the risk of crushing what you've mounted, and
where there may be allowance for thermal expansion and contration (+30C
extreme max in summer to -45C extreme minimum in winter).
Ron VE8RT
On Sun, 02 Jan 2022 07:23:56 -0800
"Oyster Town (G0IFS) via groups.io"
<nigel_clayton@...> wrote:
Thank you Ron, good suggestions to be employed when the weather calms down!
--
Ron VE8RT <ve8rt@...>
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Thanks Steve I've snipped out most of this to get to one point of interest: On Sun, 02 Jan 2022 07:47:00 -0800 "Steven Greenfield AE7HD via groups.io" <alienrelics@...> wrote: If, =if= you use another method to lock the parts in place, for instance the fiber locking nuts Ron mentions, a split ring washer can act like a spring and keep things a little more snug if the parts become loose, but temperature change or a stretched bolt is the only reasonable situation I can picture that being an issue. Thermal cycling is not mentioned on the wikipedia site but I thought that thermal cycling may have been the reason that Belleville washers were used on the link hardware of aircraft Nickel Cadmium batteries. Ron VE8RT -- Ron VE8RT <ve8rt@...>
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I posted on StackExchange about split-ring lockwashers, including a link to the NASA Fastener Design Manual.
https://diy.stackexchange.com/a/242093/129807
--
Steve Greenfield AE7HD
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You could use a jam nut that way but you risk moving both nuts together and have little or no locking. When applying a jam nut you use both hands and two wrenches. The procedure and detailed explanation are here: Using a jam nut is also a good way of removing or installing studs. There is a lot of information online about this. You may already have everything you need to do this on hand. Ron VE8RT On Sun, 2 Jan 2022 08:04:52 -0800 "Dick Bingham" <dick.bingham@...> wrote: Greetings
Once you tighten things up, how about running another nut against the nut holding everything in place. Tighten it it so it jams against the original nut.
Dick/W7wkr. CN97uj
--
Ron VE8RT <ve8rt@...>
-- Ron VE8RT <ve8rt@...>
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Lots of info.. bit ott..its a wellbrock on a mast..
Blue locktight, plus nylock locking nut against a plain washer..job done..( on just about anything on land.) only thing that can be an issue is too much of above, (if not using stainless bolts and nuts) that the head is not “ get atable” ie “ bugger” the bolt in a plastic housing is spinning, never tighten or loosen them now.. and we do all use stainless for non safety/stess related stuff ie wellbrock to mast outside in all weather conditions don’t we.
Ok not for an aircraft of spacecraft..or submarine etc..
Simon
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Like you said Steve, they're everywhere, and they're still considered acceptable even in aviation. Critical locations though will use better locking hardware. I wouldn't want to rely on split ring washers on anything mounted at the top of the tower where it cannot be easily periodically inspected. Now that I think of it I should have used drilled head bolts and lockwire on the bolts that secure my Hy-Gain Ham IV rotator. Not many amateurs that I've met lockwire hardware. Ron VE8RT On Sun, 02 Jan 2022 08:06:40 -0800 "Steven Greenfield AE7HD via groups.io" <alienrelics@...> wrote:
I posted on StackExchange about split-ring lockwashers, including a link to the NASA Fastener Design Manual.
--
Steve Greenfield AE7HD
--
Ron VE8RT <ve8rt@...>
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On Sun, Jan 2, 2022 at 07:47 AM, Steven Greenfield AE7HD wrote:
Absent any other method to lock the parts in place, split-ring lockwashers can actually hasten loosening under vibration and temperature changes. See the graph on the last page in the PDF I linked to below.
Let's see if I can link to the PDF:
http://hillcountryengineering.com/wp-content/uploads/2011/10/Split-Lockwashers-Separating-Myth-from-Truth.pdf
Sadly, there are a lot, a LOT of websites, mechanics, and even mechanical engineers giving out bad advice about split-ring lockwashers.
Steve - Thanks for the link to the article.? I learned something from your comments and that article. Roger
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I would NEVER USE LOCKING COMPOUND ON PLASTICS. Many locking compounds can destroy plastic parts over time, they are formulated for locking metal part not plastics.? Same goes for some greases. One former employee used locking compound on plastic nuts, cost ?35,000 to replace the parts.
One Italian manufacturer used a grease to ease driving screws into plastic pillars. After a year the pillars disintegrated and cost the manufacturer a lot of money.
73, Alan G8LCO.
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Why would anyone use locking compounds on plastic?
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Thermal cycling is not mentioned on the wikipedia site but I thought that
thermal cycling may have been the reason that Belleville washers were used on the link hardware of aircraft Nickel Cadmium batteries.
To clarify, Belleville washers are spring washers, much better than split ring if your intent is to provide a spring pressure that allows some movement and change in length. Much stiffer than a spring and less likely to bounce and break contact than a battery spring. I think the guidelines for Belleville washers may include that they should not be torqued down flat. I do know even the Wikipedia page specifically says they are NOT a locking mechanism. The Wikipedia page Ron links to makes a fascinating read. In any case, for antenna mounting we need hardware that can sit up there for years in the sun, wind, snow, rain, etc. without requiring constant inspection and tightening. -- Steve Greenfield AE7HD
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A rubber gasket is part of the installation kit for the 1m
loops. This is to prevent the threaded metal dome from scuffing the plastic loop
box and also it should cushion some of the mechanical stress on the Dome cover.
Hence, the fixing nuts should not be over tightened so as the compress the
casket too much. However, as already suggested; a further nut can be use as
locking nut.
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All noted Andrew, the installation has been a valuable part of my listening arsenal and is weathering well and continues to give a good account of itself.
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Q. Why would anyone use locking compound on plastic?
A. Because they think it will lock parts together without the
risk of cracking when overtightening.?? (You advised locking
compound with nylock nuts.)
People generally use too much compound, only a minute amount in
the thread space is needed. If excess runs off onto plastic parts
then they can disintegrate over time. There are a very wide range
of plastics nearly all of which are compounds with various
additives to improve moulding properties, colour, flexibility and
toughness so the reaction to compound solvents is hard to predict.
People may think that Plastics are solids and impermeable however
that's not true for many plastics. Nylons absorb water for example
as do some uncured silicone rubbers which " set" through their
bulk? by exposure to water.
Thread locking compounds set to a plastic mass when squeezed
between metal surfaces, the exclusion of oxygen and the presence
of metal ions trigger the reaction. So the compound cannot work on
plastic parts but the solvents may enter microcracks in plastics
and cause extensive damage to some plastics. Obviously the product
is supplied in a plastic bottle -not all plastics are at risk!
See
A safer option is to use two nuts, the second being used as a
lock-nut.
73, Alan G8LCO.
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Steven Greenfield AE7HD
Dick Bingham
Roger Need