What I do know about adhesives is they all have their relative
benefit...rigidity, bending, elasticity, density and the like. I was looking for an
article which I published some time back describing the different adhesives
and what their special characteristics were.
I will bang on my memory here:
* Duco...softer...seems to have a plasticizer in it...it "never" (?)
hardens...thinned out it penetrates but seems to have a softer adhesion.
When thinned with acetone it has good penetration properties. Good for
rib/spar joints?
* Ambroid...hardens with age. Thinned out with acetone it
penetrates the wood and gives a uniform joint but gets brittle with age. Brittle is
a relative word...if under high stresses it is indeed a problem, but
Ambroid will hold for 20 yeas with no problems, unless it is subjected to high
stresses where it will fracture... Good for "paper tube" to motor stick and
etc...maybe prop hanger adhesion. OK for joints where you want to soften
and "bend" in a twist or whatever. You won't know any real problems unless
your model survives about 3-4 years.
* White glues...thinned to a needed viscosity never gets the
properties back
* Aliphatic resin..."yellow glue"....thinned out with water keeps the
adhesive properties and does not shrink, but watch the weight for indoor
models. It's actually a good heat set adhesive..laminates of plywood, etc,
ironed together.
* epoxies...amazingly, has great properties even thinned out with
alcohol to a usable consistency. This may be the result of it being a
chemical reaction and not an air dry. Worth looking in to. Structural
properties are way better than acetate/acetone adhesives. When mixing, use a cup
and a gram scale to the proportions recommended. The set rate...5 minute, 10
minute, 45 minute...for what we are thinking in an indoor model..the
longer the better. Cannot be re-set...once it's set, it's there.
* CYA...great stuff, but it's hard to control the amount when
glueing. Drip a drop on a piece of glass and use a needle or sliver of fly tying
mono filament to apply to the joint. Good structural properties
* Heat set adhesives...need to be pre-prepped to thickness,
temperature, etc. reserved for a good manufacturing process. Not good stuff for
indoor models.
The big thing is surface prep in any application, especially where two
dissimilar materials want to be glued. Prop hangers to wood, wire to
wood...CLEAN the surface with a scuff of fine grit and wash/wipe with Alcohol...IPA
is best...(Isopropyl alcohol) OK...test all of these and tell me what you
come up with.
Note: fingerprints (or any oils) are the bane of adhered joints.
Rick Pangell
Editor of "The Max-Out" Newsletter of
The Magnificent Mountain Men FF Club of Colorado
In a message dated 6/26/2012 12:41:10 P.M. Mountain Daylight Time,
82.jake_at_gmail.com writes:
I don't rely on glue for bracing wire. I wrap it around the bearing at
the front and the hook at the back. I use glue just to keep it from
unraveling.
On Tue, Jun 26, 2012 at 11:19 AM, _mkirda_at_sbcglobal.net_
(mailto:mkirda_at_sbcglobal.net) <_mkirda_at_sbcglobal.net_ (mailto:mkirda_at_sbcglobal.net) > wrote:
Is this a consensus opinion? I've only ever used Duco for motor
sticks/bracing. It might explain some of the bending I saw down at USIC.
Regards.
Mike Kirda
----------------------
Gents
Don't use Duco to hold motor stick bracing wire! It is subject to creep
failure in that it yields under a continuous load. The result is that the
bracing comes loose during a flight if Duco used to hold the wire ends eg at
the front. Ambroid gives a stiffer and probably stronger joint.
Bob
Received on Tue Jun 26 2012 - 12:10:42 CEST
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