OAUSA Net - 8/25/16 - Adhesives, Thread Lockers, Repair

[DaveK]

Our net this week will be of particular interest to those who travel to remote locations where your usual repair service is not available. It is in those locations where the prepared traveler needs to be self sufficient and ready to make his own repairs. Kevin Paulson, KK6DGL will be our guest this week and will be discussing various adhesives, thread lockers, repair compounds, silicones, and other products which should be in everyone's gear bag. These same products will come in handy for all your home repairs as well. Kevin's expertise in this area is significant and the net will offer valuable information for just about everyone.

[DaveK]

These photos will be discussed by Kevin during the net. Note: they are numbered for easy reference.

What follows are Kevin's comments:

The purpose of this Net is to help you understand how various adhesives and sealants can
Improve the reliability, safety and longevity of not only a vehicles mechanical assemblies, but also Ham radio
equipment, outdoor and camping gear.

Photo # 1

At the end of this Net, you will be able to:
1. Describe the different adhesive chemistries and their benefits/challenges
2. Understand how to select the correct version to best solve your problem
3. Describe the failures most likely to occur on the trail that can be prevented or repaired with adhesives
4.Prepare your own adhesive kit that will augment the other "Tools" you carry.
5. "STOP USING SPLIT RING LOCK WASHERS".

Topics include:
Thread lockers vs traditional locking devices
Anti Seize and lubricants
Cyanoacrylates(Super Glues)
Liquid Gaskets and Sealants
Epoxies- liquids and putties
Solvent based adhesives
Two Step Acrylics

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Photo # 2

1. Anaerobic chemistry cures with lack of air and the presence of metal ions. They never dry.
2. Can stress crack some plastics. Nylon insert lock nuts are fine.
3. Increase friction by filling the air space with a hard plastic.
4. Lubricate going on, prevent rust and galvanic corrosion.
5. Allow for disassembly with no damage to assembly if proper strength selected.

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Photo # 3

Typical fastener with Blue, removable thread locker.
1. A standard threaded assembly has about 15% metal to metal contact between the threads. The rest is air space. By filling the air space with a hard plastic, you greatly increase the friction with the added benefit of sealing the threads
2. It takes as little as 100 vibration or shock load cycles to start fastener failure.
3. Fastener failure means loss of clamp load. It is the loss of clamp load that causes many squeaks and rattles that lead to wear in mechanisms.
4. It is the air space between most assemblies due to imperfect fit that initiates wear or failure.
5. Fill up the air space, reduce failure.
6. Always use hardened flat washers and nuts when using hardened bolts.

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Photo # 4

Thread locker selection:
1. Purple is low strength for fasteners under 1/4" or when some adjustability is desired.
2. Blue is medium strength and is your first choice. Both purple and blue are removable with the same hand tool you put it on with. Useful for most fasteners above the drive train. Excellent for securing vehicle accessories including Ham radios equipment.
3. Red is high strength. You need 450* F for 5 minutes to remove it. Used for high torque or shock applications. Motor or shock mounts. Also may be used for tamper resistant applications.
4. Green( sometimes blue) is a wicking thread locker for post assembly applications. Line up your assembly and tighten the fasteners. Then add a drop of wicking thread locker to lock and seal.
5. 2 free falling drops on a 3/8" bolt are all you need.

Anti Seize
1. Lubricates going on
2. Fills the air space to prevent corrosion
3. Aids in disassembly
4. Does nothing to lock fasteners together.

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Image #5

Blind hole applications.
Threaded fasteners in engine block, differential, etc

You must put the thread locker in the hole.
1. The H ole on right is a through hole. Apply thread locker to fastener. T/L is distributed during assembly.
2. The hole in middle is a blind hole. It does not have an exit hole. T/L was applied to screw and inserted. The air in the hole was compressed and most of the blue T/L was forced out with the air. Notice the bubbles at the top.
3. Proper assemble of a blind hole fastener requires putting the blue or red T/L in the hole before assembly.

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Photos # 6 & 7

Cyanoacrylates or Super Glues

1. Almost instant cure on most materials
2. Use latent moisture on parts to neutralize the acid stabilizer in the glue
3. Require a thin bond line to cure effectively.
4. Do not over-apply a Super Glue
5 Fairly rigid bond line although their are rubber toughened and flexible versions
6. Does not bond well to glass
7. Cheaper version don't handle acidic surfaces well(wood, leather, paper and some plated metals). Newer versions overcome the extra acidity in the substrates.
8. You can add baking soda or metal powder to rebuild a worn part, seal a leaky radiator hose. Luthiers( guitar builders mix it with powdered wood or bone to repair stringed instruments.

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[DaveK]

CONTINUED

Picture #8

Gasket makers and sealants
1. Designed for use in gaps up to 1/4" on flexible or rigid flanges.
2. RTV- Room Temperature Vulcanization. It turns to rubber at room temperature with moisture in the air.
3. All manufacturers make multiple formulas
4. If it smells like vinegar, it is an acetoxy(acidic acid) cure and can corrode metals, electrical wiring, and terminal ends. See above.
5. Use a high performance or non corrosive silicone(alcohol cure).
6. Adheres to oily surfaces better. Does not absorb oil.
7. Temperature ratings to about 650* F.

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Picture #9

Epoxies
1. Usually 2 part
2. Mix in correct ratio. Must mix thoroughly. Reaction produces heat that cures adhesive
3. Prefer a thicker bond line.
4. Tend to be brittle but flexible ones are available.
5.Bond to many substrates. Plastics and rubber are fair.
6. Special putty formulations can seal gas tanks and differentials.
7. Will readily bond to itself.
8. Specialized fillers can help match the properties of the parent substrate(aluminum, titanium, etc).
9. Gloves should be warn as they can cause skin reactions.

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Picture #10

Dielectric grease
1. Silicone based grease designed to displace air and moisture in electrical fittings
2. Forms a seal in dissimilar metals to prevent galvanic corrosion. Ideal on contacts where excess material is wiped away during assembly, such as ATC(blade type) fuses and terminal ends.
3. Should be used on battery terminals to prevent corrosion from battery acid.
4. If used properly, it will not act as an insulator. Remember, we are filling the voids in a fitting, not increasing the gap.

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Picture #11

Solvent based adhesives
1. Ideal for flexible substrates. Neoprene or fabric seat covers, tents ground sheets, air mattresses, fishing waders, pop up tent fabric and many others.
2. Work on shoe soles but must be taped closed at least overnight.
3. Surfaces must be clean and dry.
4. Heat speeds drying. Cold or wet weather slows it.
5. Best used in thinner applications. If used to plug a hole. Build up adhesive in layers.
6. Use in ventilated areas. Many of these are flammable.

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Picture #12

2 Step Acrylic Adhesives
Rear View Mirror Adhesive
1. Need very thin bond line
2. Structural strength. Withstands severe shock load.
3. Can be used to bond most metals, glass, even wood.
4. Poor to fair adhesion to rubber and plastics.
5. Can be used where fasteners won't fit. Ham Radio base to flexible mount. High strength neodymium magnets to ammo can battery box to temporarily hold radio.
5. Widely used to bond permanent magnets in electric motor assembly.

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Picture #12

Reference charts:

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[lrsrngr]

Looks like an informative topic and one that is relevant to everyday issues; from the man cave to the trail. Web check in for KK6CTT please.

[k9atk]

Please check in
K9atk brian
K9fog trish
Kd0exi cheyenne
Kd0gpe austin
Thanks for the check in

[KK6DYO]

Please check me in for this evening's net. Thanks.