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> From: Barry Kutner <w2up@itw.com>
> However, I'm still a little confused regarding the various "color"
> varieties of Loctite. Where should each be used? or is Permatex
> anti-seize good enough for SS bolts on Yagis, mast clamps, etc?
> Tnx/Barry W2UP
Hi Barry,
Hope you don't mind me putting this on TT. The information may be useful to
others.
Anti-seize compounds make sure things come apart. Loctite compounds make
sure things don't come apart until you want them to.
If you use an anti-seize compound you must use a lock washer or self
locking nut to keep it from vibrating loose.
If you use a Loctite compound you don't need a lock washer or lock nut.
I personnaly do not like spring type lock washers. They are not always
effective over a long time period. The star types are much better as they
grip into more material. Their downside is that they chew up the mating
faces when undone and they are not easy to find in stainless.
I do like lock nuts, but when working in stainless, the only readily
available lock nuts are the ones with a Nylon lock band. These are only
good for one installation. Then they MUST be thrown away and replaced with
a new nut. Additionally, the anti-seize compound lubricates the locking
band and makes it less effective.
So, my preference is to use a Loctite compound.
Loctite compounds:
Loctite is the Tm name for the original patent holder (like Crescent was to
adjustable open end wrenches (spanners to the UK gang)).
Currently, similar products are sold under other brand names (Permatex has
a line of thread locking products).
Thread locking compounds all share a similar generic chemistry. They are
called Anerobics. Anerobic materials cure in the absence of air. This is
exactly the opposite of how most materials, we are familiar with, cure.
Most stuff cures in the presence of air (like paint and glue...etc).
Another Anerobic compound , we are all familiar with, is Super Glue. Most
will remember that with both materials, the material trapped between the
bottle nozzle and the cap always gets hard, and has to be picked off. The
stuff in the bottle is still liquid. Simple illustration of how it works.
The material between the nozzle and cap was sealed off from the air. The
air trapped in the top of the container prevents the bottle contents from
curing.
When we put a thread locking compound into a threaded connection, the outer
threads, exposed to the air do not completely cure. The material inside the
outer thread rings completely cures.
The next neat little feature of the threadlocking materials is that when
they cure, they expand. The expansion of the compound applies pressure to
the mating thread faces and locks the fastener. Better antenna building
through modern chemistry!
Since the chemists, who formulate these products, didn't put any oil,
grease, or water in them, we might understand why they don't want to have
our threads comtaminated before applying the compounds. Contaminants MUCK
up the chemistry and render the compounds useless.
Sorry to put through all of this to get to answering your question, but you
now know enough to use it properly.
The basic differences between the various grades of compound are the
expansion rates cured strengths. The different grades bond to clean
surfaces equally. The strengths of the cured compound determines how hard
it is to get them to come apart.
To over simplify the discussion, there are three basic grades. Call them
low, medium and high strength locking power.
Fortunately the different manufacturers have maintained some consistency in
this, unlike the computer & software/hardware Knuckleheads.
Blue compounds are the low strength type. They are usually called
"threadlocker" or some such name.
Red compounds are the medium strength type. They are called "bearing mount"
or ....
Green compounds are high strength types and should be associated with terms
like "nuclear bomb" or "cruise missle" when thinking about getting them
apart.
My advice is to use Blue, threadlocking stuff on antennas. It gets the job
done and comes apart with the tools in your pouch.
The Red usually needs a little help from a torch to get it to breakdown and
come apart.
The green also needs a torch to get it apart. You've just got to bring a
bigger torch up the tower, some call it a "gas axe". You just flame cut the
metal parts apart cuz the green stuff will laugh in your face!
There are many other grades, specialized for varying environments, but
let's Keep It Simple Stupid and stick with the blue stuff.
73, Kurt
YagiStress - The Ultimate Mechanical Design Software for Yagi's
Visit - http://freeyellow.com/members3/yagistress
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