This is out of curiosity:

How good of a bond can one achieve with epoxy to aluminum? How good can
one achieve with epoxy that ordinary folks can mail-order, vs. what folks
who have the ear of a Locktite sales rep and applications engineer can
achieve? How good can one achieve with JB Weld?

An Internet acquaintance has a scale model airplane that needs a
driveshaft driven by an 049 engine (that's a bitty one that swings a 5"
prop, not a humongous one that swings a 12" prop -- 1/20th cubic inch,
not 1/2). His current driveshaft uses a solid aluminum rod, and is
heavier than he'd like.

Because of the way the plane balances with the current shaft, every gram
he takes out of the shaft takes out more than two grams from the plane,
because he's currently got a buttload of weight in the nose.

I'm thinking that one could machine ends out of aluminum, then plug them
into a thin-wall (.035"), 1/2" or 5/8" diameter tube made of 2024. I'm
also thinking that bonding everything with epoxy would be a valid way to
go -- but I'm not so sure about the epoxy in a part that's going to be
subject to lots of vibration in at least eight of the six available
degrees of freedom.

Threading such thin wall tubing makes me think that it'll just break.

Welding makes me think it'll never happen.

Soldering???

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

"Tim Wescott" wrote in message
...
This is out of curiosity:

How good of a bond can one achieve with epoxy to aluminum? How good can
one achieve with epoxy that ordinary folks can mail-order, vs. what folks
who have the ear of a Locktite sales rep and applications engineer can
achieve? How good can one achieve with JB Weld?

An Internet acquaintance has a scale model airplane that needs a
driveshaft driven by an 049 engine (that's a bitty one that swings a 5"
prop, not a humongous one that swings a 12" prop -- 1/20th cubic inch,
not 1/2). His current driveshaft uses a solid aluminum rod, and is
heavier than he'd like.

Because of the way the plane balances with the current shaft, every gram
he takes out of the shaft takes out more than two grams from the plane,
because he's currently got a buttload of weight in the nose.

I'm thinking that one could machine ends out of aluminum, then plug them
into a thin-wall (.035"), 1/2" or 5/8" diameter tube made of 2024. I'm
also thinking that bonding everything with epoxy would be a valid way to
go -- but I'm not so sure about the epoxy in a part that's going to be
subject to lots of vibration in at least eight of the six available
degrees of freedom.

Threading such thin wall tubing makes me think that it'll just break.

Welding makes me think it'll never happen.

Soldering???

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com


Epoxy looses a lot of its strength and toughness if it is queezed into too
small a gap. It also delaminates with changes in temperature more easily. I
think what you ideally want for this applications is one of the Loctite 6XX
series of retaining compounds. Mcmaster sells them in small sizes. They have
them for different gap sizes and temperature ranges etc. Once you bond
cylindrical parts with these, they do not come apart.

In other applications, epoxy peel strength on anodized (or naturally
oxidized) aluminum is not very high unless it has been roughened or etched.

If it were me, I'd try Loctite Bearing
retaining compound, being very careful
about fit, curing time, etc.

Tim Wescott wrote:
This is out of curiosity:

How good of a bond can one achieve with epoxy to aluminum? How good can
one achieve with epoxy that ordinary folks can mail-order, vs. what folks
who have the ear of a Locktite sales rep and applications engineer can
achieve? How good can one achieve with JB Weld?

An Internet acquaintance has a scale model airplane that needs a
driveshaft driven by an 049 engine (that's a bitty one that swings a 5"
prop, not a humongous one that swings a 12" prop -- 1/20th cubic inch,
not 1/2). His current driveshaft uses a solid aluminum rod, and is
heavier than he'd like.

Because of the way the plane balances with the current shaft, every gram
he takes out of the shaft takes out more than two grams from the plane,
because he's currently got a buttload of weight in the nose.

I'm thinking that one could machine ends out of aluminum, then plug them
into a thin-wall (.035"), 1/2" or 5/8" diameter tube made of 2024. I'm
also thinking that bonding everything with epoxy would be a valid way to
go -- but I'm not so sure about the epoxy in a part that's going to be
subject to lots of vibration in at least eight of the six available
degrees of freedom.

Threading such thin wall tubing makes me think that it'll just break.

Welding makes me think it'll never happen.

Soldering???

"anorton" wrote in message
m...

"Tim Wescott" wrote in message
...
This is out of curiosity:

How good of a bond can one achieve with epoxy to aluminum? How good can
one achieve with epoxy that ordinary folks can mail-order, vs. what folks
who have the ear of a Locktite sales rep and applications engineer can
achieve? How good can one achieve with JB Weld?

An Internet acquaintance has a scale model airplane that needs a
driveshaft driven by an 049 engine (that's a bitty one that swings a 5"
prop, not a humongous one that swings a 12" prop -- 1/20th cubic inch,
not 1/2). His current driveshaft uses a solid aluminum rod, and is
heavier than he'd like.

Because of the way the plane balances with the current shaft, every gram
he takes out of the shaft takes out more than two grams from the plane,
because he's currently got a buttload of weight in the nose.

I'm thinking that one could machine ends out of aluminum, then plug them
into a thin-wall (.035"), 1/2" or 5/8" diameter tube made of 2024. I'm
also thinking that bonding everything with epoxy would be a valid way to
go -- but I'm not so sure about the epoxy in a part that's going to be
subject to lots of vibration in at least eight of the six available
degrees of freedom.

Threading such thin wall tubing makes me think that it'll just break.

Welding makes me think it'll never happen.

Soldering???

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com


Epoxy looses a lot of its strength and toughness if it is queezed into too
small a gap. It also delaminates with changes in temperature more easily.
I think what you ideally want for this applications is one of the Loctite
6XX series of retaining compounds. Mcmaster sells them in small sizes.
They have them for different gap sizes and temperature ranges etc. Once
you bond cylindrical parts with these, they do not come apart.

In other applications, epoxy peel strength on anodized (or naturally
oxidized) aluminum is not very high unless it has been roughened or
etched.

If he's plugging ends into a tube , there is only shear stress . Using
aluminum for both parts will insure similar expansion , why not use one of
the cyanoacrilates per above ? Preferably one for tight fits , since
balance is fairly important at 17,000 RPM's ...
--
Snag

On Fri, 20 Sep 2013 12:36:51 -0700, anorton wrote:

"Tim Wescott" wrote in message
...
This is out of curiosity:

How good of a bond can one achieve with epoxy to aluminum? How good
can one achieve with epoxy that ordinary folks can mail-order, vs. what
folks who have the ear of a Locktite sales rep and applications
engineer can achieve? How good can one achieve with JB Weld?

An Internet acquaintance has a scale model airplane that needs a
driveshaft driven by an 049 engine (that's a bitty one that swings a 5"
prop, not a humongous one that swings a 12" prop -- 1/20th cubic inch,
not 1/2). His current driveshaft uses a solid aluminum rod, and is
heavier than he'd like.

Because of the way the plane balances with the current shaft, every
gram he takes out of the shaft takes out more than two grams from the
plane, because he's currently got a buttload of weight in the nose.

I'm thinking that one could machine ends out of aluminum, then plug
them into a thin-wall (.035"), 1/2" or 5/8" diameter tube made of 2024.
I'm also thinking that bonding everything with epoxy would be a valid
way to go -- but I'm not so sure about the epoxy in a part that's going
to be subject to lots of vibration in at least eight of the six
available degrees of freedom.

Threading such thin wall tubing makes me think that it'll just break.

Welding makes me think it'll never happen.

Soldering???

--

Tim Wescott Wescott Design Services http://www.wescottdesign.com


Epoxy looses a lot of its strength and toughness if it is queezed into
too small a gap. It also delaminates with changes in temperature more
easily. I think what you ideally want for this applications is one of
the Loctite 6XX series of retaining compounds. Mcmaster sells them in
small sizes. They have them for different gap sizes and temperature
ranges etc. Once you bond cylindrical parts with these, they do not
come apart.

In other applications, epoxy peel strength on anodized (or naturally
oxidized) aluminum is not very high unless it has been roughened or
etched.

So, 603 or 609, or maybe 620 if what I'm considering counts as "high
temperature"?

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

On Fri, 20 Sep 2013 14:03:50 -0500, Tim Wescott
wrote:

This is out of curiosity:

How good of a bond can one achieve with epoxy to aluminum? How good can
one achieve with epoxy that ordinary folks can mail-order, vs. what folks
who have the ear of a Locktite sales rep and applications engineer can
achieve? How good can one achieve with JB Weld?

An Internet acquaintance has a scale model airplane that needs a
driveshaft driven by an 049 engine (that's a bitty one that swings a 5"
prop, not a humongous one that swings a 12" prop -- 1/20th cubic inch,
not 1/2). His current driveshaft uses a solid aluminum rod, and is
heavier than he'd like.

Because of the way the plane balances with the current shaft, every gram
he takes out of the shaft takes out more than two grams from the plane,
because he's currently got a buttload of weight in the nose.

I'm thinking that one could machine ends out of aluminum, then plug them
into a thin-wall (.035"), 1/2" or 5/8" diameter tube made of 2024. I'm
also thinking that bonding everything with epoxy would be a valid way to
go -- but I'm not so sure about the epoxy in a part that's going to be
subject to lots of vibration in at least eight of the six available
degrees of freedom.

Threading such thin wall tubing makes me think that it'll just break.

Welding makes me think it'll never happen.

Soldering???

I'm sorry I won't be around to discuss this further, but here are a
few points to consider:

1) You're talking about shear loads, at which epoxy is very good.

2) The amine curing agents for epoxy, which are the ones we can get at
hardware stores and marine supplies, give you the lowest temperature
tolerance and rarely exceed 5,000 psi in cured epoxy. You can achieve
10,000 psi with other curing agents, but you'll have to Google "epoxy
curing agents" and spend some time looking around. Amine cures are
good for around 180 deg. F. You can get another 40 deg. out of other
agents.

3) With aluminum, the surface treatment is everything. They glue
airplane wings together by applying a phosphoric acid anodize. You can
get about the same strength by doing a good scratch-in job. Maybe
someone here can help.

4) With a high performance epoxy, you want a 0.003" - 0.004"
clearance, or your strength will be a fraction of what it can be.

Good luck!

Ed Huntress

On 9/20/2013 3:46 PM, Ed Huntress wrote:
On Fri, 20 Sep 2013 14:03:50 -0500, Tim Wescott
wrote:

This is out of curiosity:

How good of a bond can one achieve with epoxy to aluminum? How good can
one achieve with epoxy that ordinary folks can mail-order, vs. what folks
who have the ear of a Locktite sales rep and applications engineer can
achieve? How good can one achieve with JB Weld?

An Internet acquaintance has a scale model airplane that needs a
driveshaft driven by an 049 engine (that's a bitty one that swings a 5"
prop, not a humongous one that swings a 12" prop -- 1/20th cubic inch,
not 1/2). His current driveshaft uses a solid aluminum rod, and is
heavier than he'd like.

Because of the way the plane balances with the current shaft, every gram
he takes out of the shaft takes out more than two grams from the plane,
because he's currently got a buttload of weight in the nose.

I'm thinking that one could machine ends out of aluminum, then plug them
into a thin-wall (.035"), 1/2" or 5/8" diameter tube made of 2024. I'm
also thinking that bonding everything with epoxy would be a valid way to
go -- but I'm not so sure about the epoxy in a part that's going to be
subject to lots of vibration in at least eight of the six available
degrees of freedom.

Threading such thin wall tubing makes me think that it'll just break.

Welding makes me think it'll never happen.

Soldering???

I'm sorry I won't be around to discuss this further, but here are a
few points to consider:

1) You're talking about shear loads, at which epoxy is very good.

2) The amine curing agents for epoxy, which are the ones we can get at
hardware stores and marine supplies, give you the lowest temperature
tolerance and rarely exceed 5,000 psi in cured epoxy. You can achieve
10,000 psi with other curing agents, but you'll have to Google "epoxy
curing agents" and spend some time looking around. Amine cures are
good for around 180 deg. F. You can get another 40 deg. out of other
agents.

3) With aluminum, the surface treatment is everything. They glue
airplane wings together by applying a phosphoric acid anodize. You can
get about the same strength by doing a good scratch-in job. Maybe
someone here can help.

I want to but in here - But - first hand stuff.

What Ed said.
Then...
Appropriate primer before epoxy.


4) With a high performance epoxy, you want a 0.003" - 0.004"
clearance, or your strength will be a fraction of what it can be.

Good luck!

Ed Huntress

Tim Wescott fired this volley in
:

Threading such thin wall tubing makes me think that it'll just break.


Me... I'd just rough up the od of the plug (maybe even lightly knurl it)
and rough the id of the tube, then PRESS them together with an interference
fit (and maybe some permanent LocTite to fill the surface imperfections and
help with the strength). If that wasn't strong enough for my tastes, I'd
either peen or pin each plug in a couple of places.

I think at the rpms of an 0.049, you're talking about a chancy part. Any
radial misalignment or imbalance is going to shake things fiercely.

LLoyd

On Fri, 20 Sep 2013 16:05:26 -0500, Lloyd E. Sponenburgh wrote:

Tim Wescott fired this volley in
:

Threading such thin wall tubing makes me think that it'll just break.


Me... I'd just rough up the od of the plug (maybe even lightly knurl it)
and rough the id of the tube, then PRESS them together with an
interference fit (and maybe some permanent LocTite to fill the surface
imperfections and help with the strength). If that wasn't strong enough
for my tastes, I'd either peen or pin each plug in a couple of places.

I think at the rpms of an 0.049, you're talking about a chancy part.
Any radial misalignment or imbalance is going to shake things fiercely.

LLoyd

Well, I was thinking one of the old 15,000 RPM ones, not the new 35,000
RPM ones.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

"Tim Wescott" wrote in message
...
On Fri, 20 Sep 2013 12:36:51 -0700, anorton wrote:

"Tim Wescott" wrote in message
...
This is out of curiosity:

How good of a bond can one achieve with epoxy to aluminum? How good
can one achieve with epoxy that ordinary folks can mail-order, vs. what
folks who have the ear of a Locktite sales rep and applications
engineer can achieve? How good can one achieve with JB Weld?

An Internet acquaintance has a scale model airplane that needs a
driveshaft driven by an 049 engine (that's a bitty one that swings a 5"
prop, not a humongous one that swings a 12" prop -- 1/20th cubic inch,
not 1/2). His current driveshaft uses a solid aluminum rod, and is
heavier than he'd like.

Because of the way the plane balances with the current shaft, every
gram he takes out of the shaft takes out more than two grams from the
plane, because he's currently got a buttload of weight in the nose.

I'm thinking that one could machine ends out of aluminum, then plug
them into a thin-wall (.035"), 1/2" or 5/8" diameter tube made of 2024.
I'm also thinking that bonding everything with epoxy would be a valid
way to go -- but I'm not so sure about the epoxy in a part that's going
to be subject to lots of vibration in at least eight of the six
available degrees of freedom.

Threading such thin wall tubing makes me think that it'll just break.

Welding makes me think it'll never happen.

Soldering???

--

Tim Wescott Wescott Design Services http://www.wescottdesign.com


Epoxy looses a lot of its strength and toughness if it is queezed into
too small a gap. It also delaminates with changes in temperature more
easily. I think what you ideally want for this applications is one of
the Loctite 6XX series of retaining compounds. Mcmaster sells them in
small sizes. They have them for different gap sizes and temperature
ranges etc. Once you bond cylindrical parts with these, they do not
come apart.

In other applications, epoxy peel strength on anodized (or naturally
oxidized) aluminum is not very high unless it has been roughened or
etched.

So, 603 or 609, or maybe 620 if what I'm considering counts as "high
temperature"?

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com


You can look at the data sheets on the loctite/henkel web site and decide
for yourself. It does depend what kind of gap you plan to leave.
http://www.henkelna.com/index.htm just search for the product name.

"Tim Wescott" wrote in message
...

snip

I'm thinking that one could machine ends out of aluminum, then plug them
into a thin-wall (.035"), 1/2" or 5/8" diameter tube made of 2024. I'm
also thinking that bonding everything with epoxy would be a valid way to
go -- but I'm not so sure about the epoxy in a part that's going to be
subject to lots of vibration in at least eight of the six available
degrees of freedom.

Threading such thin wall tubing makes me think that it'll just break.

Welding makes me think it'll never happen.

Soldering???

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

I used to have a Testors BD-5, can't remember if it had a shaft extension or
not.

Some of my R/C helicopters have a shaft drive to the tail rotor and use
arrow shaft. Some use aluminum, some carbon fiber arrow shafts. These
aluminum one have inserts, can't remember for sure if they are glued in or
shaft internal, collar external clamping to the shaft. I would consider a
carbon fiber arrow shaft with aluminum fittings epoxied on, perhaps JB weld
or other strong epoxy. You may want to look at some R/C heli parts, lists
and exploded views are available online.

RogerN

Tim Wescott fired this volley in
:

Well, I was thinking one of the old 15,000 RPM ones, not the new 35,000
RPM ones.


They've pretty much always had both since the early 1960s.

"Hornets" were available since I started modeling.

Lloyd

On Fri, 20 Sep 2013 17:28:49 -0500, "RogerN"
wrote:

"Tim Wescott" wrote in message
m...

snip

I'm thinking that one could machine ends out of aluminum, then plug them
into a thin-wall (.035"), 1/2" or 5/8" diameter tube made of 2024. I'm
also thinking that bonding everything with epoxy would be a valid way to
go -- but I'm not so sure about the epoxy in a part that's going to be
subject to lots of vibration in at least eight of the six available
degrees of freedom.

Threading such thin wall tubing makes me think that it'll just break.

Welding makes me think it'll never happen.

Soldering???

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

I used to have a Testors BD-5, can't remember if it had a shaft extension or
not.

Some of my R/C helicopters have a shaft drive to the tail rotor and use
arrow shaft. Some use aluminum, some carbon fiber arrow shafts. These
aluminum one have inserts, can't remember for sure if they are glued in or
shaft internal, collar external clamping to the shaft. I would consider a
carbon fiber arrow shaft with aluminum fittings epoxied on, perhaps JB weld
or other strong epoxy. You may want to look at some R/C heli parts, lists
and exploded views are available online.

RogerN

JB Weld is not a strong epoxy. It's an ordinary amine-cure epoxy
that's filled with steel powder, and its strength is typical -- less
than 4,000 psi under ideal conditions.

They make some wild temperature claims for it, but my guess is that
they're talking about the temperature at which it breaks down and
begins to carbonize -- 550 deg. F. It's lost all useable strength long
before you reach that temperature.

--
Ed Huntress

"Ed Huntress" wrote in message
...

On Fri, 20 Sep 2013 17:28:49 -0500, "RogerN"
wrote:

snip

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

I used to have a Testors BD-5, can't remember if it had a shaft extension
or
not.

Some of my R/C helicopters have a shaft drive to the tail rotor and use
arrow shaft. Some use aluminum, some carbon fiber arrow shafts. These
aluminum one have inserts, can't remember for sure if they are glued in or
shaft internal, collar external clamping to the shaft. I would consider a
carbon fiber arrow shaft with aluminum fittings epoxied on, perhaps JB
weld
or other strong epoxy. You may want to look at some R/C heli parts, lists
and exploded views are available online.

RogerN

JB Weld is not a strong epoxy. It's an ordinary amine-cure epoxy
that's filled with steel powder, and its strength is typical -- less
than 4,000 psi under ideal conditions.

They make some wild temperature claims for it, but my guess is that
they're talking about the temperature at which it breaks down and
begins to carbonize -- 550 deg. F. It's lost all useable strength long
before you reach that temperature.

--
Ed Huntress

Why do you need a stronger epoxy for an .049 engine? The engines on my R/C
helicopters include .60 2-stroke and .90 4-stroke and I've never had a drive
shaft failure from JB-weld of the fittings in the tail rotor drive shaft.
My tail rotor blades are around 10-12" swing with variable pitch, the models
are 10-11lbs, they shake if out of balance, still the JB-Weld or other
4000PSI epoxy has never failed, the shafts get destroyed in a crash but
never had an epoxy failure so far. I haven't had that good of luck with 5
minute epoxy. Note my drive shafts are supported at each end, I'm not sure
I'd want a 5" extension on an .049 without support. Also my tail rotor
shafts aren't close to the engine so there is no high temperature problem, I
doubt an 049 would get very hot on the shaft, never had problems with props
melting or anything like that.

On a side note, some have had problems with the muffler coming loose on the
4-stroke engines, they use JB-weld and it holds up on the exhaust pipe of
the model engines.

RogerN

"RogerN" fired this volley in
:

On a side note, some have had problems with the muffler coming loose
on the 4-stroke engines, they use JB-weld and it holds up on the
exhaust pipe of the model engines.


If they did, they're not 'modelers', they're hacks.

C'mon! That's like holding the motor on a DuraPlane with rubber bands!

Y'don't glue a friggin' muffler on! You FIX it mechanically.

Besides -- WHICH 4-strokes had that problem? I've got three sizes of OS
4-strokes, and never had a single part work loose.

Lloyd


Lloyd

"Lloyd E. Sponenburgh" wrote in message
. 3.70...

"RogerN" fired this volley in
:

On a side note, some have had problems with the muffler coming loose
on the 4-stroke engines, they use JB-weld and it holds up on the
exhaust pipe of the model engines.


If they did, they're not 'modelers', they're hacks.

C'mon! That's like holding the motor on a DuraPlane with rubber bands!

Y'don't glue a friggin' muffler on! You FIX it mechanically.

Besides -- WHICH 4-strokes had that problem? I've got three sizes of OS
4-strokes, and never had a single part work loose.

Lloyd


Lloyd

The YS 90 heli engine is the one they had trouble with, not sure if the
problem was on any other engines or not. The fitting is like a flare
fitting, male threads on the exhaust header. I take it loctite didn't hold,
or anything else until someone tried JB-Weld. Not sure if it's removable
though, the heat may break it down.

I heard that was a problem with the 4-strokes and JB weld was about the only
way anyone had success with. They seemed like pretty serious modelers, a
guy I flew with ran over a drum of fuel a year and was very meticulous, he
could fly the heli inverted near the ground, I saw him barely scrape his
blades once on the asphalt. You can call him a hack but I figure he can fly
circles around most "modelers", inverted backward rolling circles or
whatever.

RogerN

"RogerN" fired this volley in
m:

They seemed like pretty serious modelers, a
guy I flew with ran over a drum of fuel a year and was very
meticulous, he could fly the heli inverted near the ground, I saw him
barely scrape his blades once on the asphalt. You can call him a hack
but I figure he can fly circles around most "modelers", inverted
backward rolling circles or whatever.


That's a flyer. I've known some of them who could stunt rotary wings
that weren't even designed to fly upright; but some of those couldn't
build a folded napkin, instead buying what they flew. Some could.

Eye-hand coordination does not a modeler make; nor does it make a metal
craftsman. (helps, though).

Lloyd

"Lloyd E. Sponenburgh" wrote in message
. 3.70...

"RogerN" fired this volley in
om:

They seemed like pretty serious modelers, a
guy I flew with ran over a drum of fuel a year and was very
meticulous, he could fly the heli inverted near the ground, I saw him
barely scrape his blades once on the asphalt. You can call him a hack
but I figure he can fly circles around most "modelers", inverted
backward rolling circles or whatever.


That's a flyer. I've known some of them who could stunt rotary wings
that weren't even designed to fly upright; but some of those couldn't
build a folded napkin, instead buying what they flew. Some could.

Eye-hand coordination does not a modeler make; nor does it make a metal
craftsman. (helps, though).

Lloyd

It's a bit difficult to know how to rate a modelers modeling skills on a
helicopter, anyone that assembles the kit can have a heli that looks pretty
normal. This guy was pretty meticulous, balanced and adjusted everything to
perfection, loctite on the bearing races to the shafts, went extra miles to
assemble the heli to perfection.

The most skillful modeler I met was Tom Ingram, he lived in Mt Vernon when I
did. He was the Tom from Harry Higgley's book "Tom's Techniques" and also
"There are no Secrets". I didn't know he was that "Tom" when I visited his
home looking at models and admiring the craftsmanship. I found out he used
to work for Top Flite and was the builder of some of the models on the
advertisement and boxes of Top Flite models. When I saw him flying at the
field he had a Sig Kadet Senior and it looked like a show model.

To ramble on ... I used to have a FliteLine Scat Cat 500, I ordered the OS
front intake, rear exhaust engine because I wanted to put a pipe on it.
What came in was the OS 46 Ducted Fan engine, it was rear intake, rear
exhaust. Since it was a more expensive engine, I went with it anyway even
though I had to modify the plane for the rear intake. When it got in the
air and on the pipe, it was pretty fast, it was hard to tell if it slowed
down when pointed straight up, I'm sure it did though.

So the heli modeler that, like most others, used JB Weld on his YS-90
4-Stroke Heli engine exhaust fitting, maybe wasn't quite a Tom Ingram skill
level, he was probably a top 80-85% of model heli building skills. I've
seen kids trained by play stations that could fly the heck out of a model
helicopter, but they didn't know how to set them up properly or any of the
real life skills you get modeling that you don't get on video games.

RogerN

On Fri, 20 Sep 2013 19:41:27 -0500, "RogerN"
wrote:

"Ed Huntress" wrote in message
.. .

On Fri, 20 Sep 2013 17:28:49 -0500, "RogerN"
wrote:

snip

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

I used to have a Testors BD-5, can't remember if it had a shaft extension
or
not.

Some of my R/C helicopters have a shaft drive to the tail rotor and use
arrow shaft. Some use aluminum, some carbon fiber arrow shafts. These
aluminum one have inserts, can't remember for sure if they are glued in or
shaft internal, collar external clamping to the shaft. I would consider a
carbon fiber arrow shaft with aluminum fittings epoxied on, perhaps JB
weld
or other strong epoxy. You may want to look at some R/C heli parts, lists
and exploded views are available online.

RogerN

JB Weld is not a strong epoxy. It's an ordinary amine-cure epoxy
that's filled with steel powder, and its strength is typical -- less
than 4,000 psi under ideal conditions.

They make some wild temperature claims for it, but my guess is that
they're talking about the temperature at which it breaks down and
begins to carbonize -- 550 deg. F. It's lost all useable strength long
before you reach that temperature.

--
Ed Huntress

Why do you need a stronger epoxy for an .049 engine?

I don't know if you do. I was commenting on JB Weld. It's good stuff
that solves a lot of problems, but I've heard from many people who
think it's a "strong" epoxy. It's not. It's run-of-the-mill in the
strength department. Elmer's two-part epoxy probably has the same
strength.

The engines on my R/C
helicopters include .60 2-stroke and .90 4-stroke and I've never had a drive
shaft failure from JB-weld of the fittings in the tail rotor drive shaft.
My tail rotor blades are around 10-12" swing with variable pitch, the models
are 10-11lbs, they shake if out of balance, still the JB-Weld or other
4000PSI epoxy has never failed, the shafts get destroyed in a crash but
never had an epoxy failure so far. I haven't had that good of luck with 5
minute epoxy.

No surprise. Five-minute epoxy is very compromised for the sake of the
quick cure. It's weak, it can be brittle (depending on brand and
formulation), and it's usually not even waterproof. A standard
slow-cure, room-temperature cure, amine-cure epoxy is very waterproof.

Note my drive shafts are supported at each end, I'm not sure
I'd want a 5" extension on an .049 without support. Also my tail rotor
shafts aren't close to the engine so there is no high temperature problem, I
doubt an 049 would get very hot on the shaft, never had problems with props
melting or anything like that.

On a side note, some have had problems with the muffler coming loose on the
4-stroke engines, they use JB-weld and it holds up on the exhaust pipe of
the model engines.

RogerN

Roger, I'm just telling you what the measured properties of those
materials are. They're well-known in the adhesives field. I wrote a
12-page report on them years ago for American Machinist, but these
basic epoxies haven't changed. They've been the same materials since
the '60s.

JB Weld's metal filler probably provides some advantages in a variety
of situations. Bond strength is just not among them. And the ability
of amine-cured epoxies to tolerate high temperates doesn't vary much
among brands.

--
Ed Huntress

On Fri, 20 Sep 2013 12:36:51 -0700, "anorton"
wrote:


"Tim Wescott" wrote in message
m...
This is out of curiosity:

How good of a bond can one achieve with epoxy to aluminum? How good can
one achieve with epoxy that ordinary folks can mail-order, vs. what folks
who have the ear of a Locktite sales rep and applications engineer can
achieve? How good can one achieve with JB Weld?

An Internet acquaintance has a scale model airplane that needs a
driveshaft driven by an 049 engine (that's a bitty one that swings a 5"
prop, not a humongous one that swings a 12" prop -- 1/20th cubic inch,
not 1/2). His current driveshaft uses a solid aluminum rod, and is
heavier than he'd like.

Because of the way the plane balances with the current shaft, every gram
he takes out of the shaft takes out more than two grams from the plane,
because he's currently got a buttload of weight in the nose.

I'm thinking that one could machine ends out of aluminum, then plug them
into a thin-wall (.035"), 1/2" or 5/8" diameter tube made of 2024. I'm
also thinking that bonding everything with epoxy would be a valid way to
go -- but I'm not so sure about the epoxy in a part that's going to be
subject to lots of vibration in at least eight of the six available
degrees of freedom.

Threading such thin wall tubing makes me think that it'll just break.

Welding makes me think it'll never happen.

Soldering???

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com


Epoxy looses a lot of its strength and toughness if it is queezed into too
small a gap. It also delaminates with changes in temperature more easily. I
think what you ideally want for this applications is one of the Loctite 6XX
series of retaining compounds. Mcmaster sells them in small sizes. They have
them for different gap sizes and temperature ranges etc. Once you bond
cylindrical parts with these, they do not come apart.

In other applications, epoxy peel strength on anodized (or naturally
oxidized) aluminum is not very high unless it has been roughened or etched.

Good post!


"The socialist movement takes great pains to circulate frequently new labels for its ideally constructed state.
Each worn-out label is replaced by another which raises hopes of an ultimate solution of the insoluble basic
problem of Socialism, until it becomes obvious that nothing has been changed but the name.
The most recent slogan is "State Capitalism."[Fascism] It is not commonly realized that this covers nothing more
than what used to be called Planned Economy and State Socialism, and that State Capitalism, Planned Economy,
and State Socialism diverge only in non-essentials from the "classic" ideal of egalitarian Socialism. - Ludwig von Mises (1922)

On Fri, 20 Sep 2013 17:28:49 -0500, "RogerN"
wrote:

"Tim Wescott" wrote in message
m...

snip

I'm thinking that one could machine ends out of aluminum, then plug them
into a thin-wall (.035"), 1/2" or 5/8" diameter tube made of 2024. I'm
also thinking that bonding everything with epoxy would be a valid way to
go -- but I'm not so sure about the epoxy in a part that's going to be
subject to lots of vibration in at least eight of the six available
degrees of freedom.

Threading such thin wall tubing makes me think that it'll just break.

Welding makes me think it'll never happen.

Soldering???

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

I used to have a Testors BD-5, can't remember if it had a shaft extension or
not.

Some of my R/C helicopters have a shaft drive to the tail rotor and use
arrow shaft. Some use aluminum, some carbon fiber arrow shafts. These
aluminum one have inserts, can't remember for sure if they are glued in or
shaft internal, collar external clamping to the shaft. I would consider a
carbon fiber arrow shaft with aluminum fittings epoxied on, perhaps JB weld
or other strong epoxy. You may want to look at some R/C heli parts, lists
and exploded views are available online.

RogerN

Ive built many thousands of aluminum arrows with the inserts. JB Weld
does a fine job, as do several of the model makers CA glues. I wouldnt
use the Super Glue down at the Home Despot.

Most guys use Duco cement and it lasts a very long time under loading
and impact.


Gunner


"The socialist movement takes great pains to circulate frequently new labels for its ideally constructed state.
Each worn-out label is replaced by another which raises hopes of an ultimate solution of the insoluble basic
problem of Socialism, until it becomes obvious that nothing has been changed but the name.
The most recent slogan is "State Capitalism."[Fascism] It is not commonly realized that this covers nothing more
than what used to be called Planned Economy and State Socialism, and that State Capitalism, Planned Economy,
and State Socialism diverge only in non-essentials from the "classic" ideal of egalitarian Socialism. - Ludwig von Mises (1922)

"RogerN" fired this volley in news:mJWdnT_T-
:

Harry Higgley's book

Yeah, I've got Higgley's line, too. Good stuff.

The 'master modelers' down here who showed up at the DeLand field (back
when I lived there) are Bob Fiorenze and Bob Violet, both of jets fame.
In addition to the big "Jets over DeLand" annual show, the two Bobs would
show up on odd days for prototype testing. We happened to have the
longest paved model runway (in decent repair) in central Florida.

Even those master-modelers with consummate flying skills can have
problems, especially at real airspeeds of 200 knots. I've seen more than
one of those high-dollar jets (once only ducted fan, but some now real
turbines) come down as 'silver rain'.


LLoyd

On Sat, 21 Sep 2013 00:05:25 -0400, Ed Huntress wrote:

Note my drive shafts are supported at each end, I'm not sure
I'd want a 5" extension on an .049 without support. Also my tail rotor

I'd planned on a bearing at the far end, and a U-joint (ball and pin,
like on a model boat) at the near end.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

On Sat, 21 Sep 2013 11:12:04 -0500, Tim Wescott
wrote:

On Sat, 21 Sep 2013 00:05:25 -0400, Ed Huntress wrote:

Note my drive shafts are supported at each end, I'm not sure
I'd want a 5" extension on an .049 without support. Also my tail rotor

I'd planned on a bearing at the far end, and a U-joint (ball and pin,
like on a model boat) at the near end.

That was Roger, not me. I'm the glue guy, not the model guy. g

--
Ed Huntress

On 9/20/2013 3:03 PM, Tim Wescott wrote:
This is out of curiosity:

How good of a bond can one achieve with epoxy to aluminum? How good can
one achieve with epoxy that ordinary folks can mail-order, vs. what folks
who have the ear of a Locktite sales rep and applications engineer can
achieve? How good can one achieve with JB Weld?
snip

Everybody here has stayed on the adhesive train! I say use a mechanical
solution. Pin or swage it together!

"Lloyd E. Sponenburgh" wrote in message
. 3.70...

"RogerN" fired this volley in news:mJWdnT_T-
:

Harry Higgley's book

Yeah, I've got Higgley's line, too. Good stuff.

The 'master modelers' down here who showed up at the DeLand field (back
when I lived there) are Bob Fiorenze and Bob Violet, both of jets fame.
In addition to the big "Jets over DeLand" annual show, the two Bobs would
show up on odd days for prototype testing. We happened to have the
longest paved model runway (in decent repair) in central Florida.

Even those master-modelers with consummate flying skills can have
problems, especially at real airspeeds of 200 knots. I've seen more than
one of those high-dollar jets (once only ducted fan, but some now real
turbines) come down as 'silver rain'.


LLoyd

That's awesome, I used to have a "Jets over DeLand" video. I'm around 1-1/2
hours from Metropolis and they have a big, for this area, jet fly there
every year.

I did a little search for the YS 4-stroke and JB Weld, found lot's of people
using it like loc-tite. I did see a mention that it's not permanent because
the heat weakens it enough to disassemble.

My best helicopter has a 4-stroke, I got it barely used from an eBay seller,
the reserve wasn't met but he offered it to me. The buddy I fly with that
used to burns more than a drum of fuel knew the heli and the builder. It
has the exhaust nut JB-welded but I've not needed to remove it so far. I
can remove all the bolts out of a side frame and remove the engine with the
exhaust attached.

All my glow fuel heli's are old school where the cyclic and collective pitch
is mixed mechanically by levers, today they use "CCPM" Cyclic Collective
Pitch Mixing on the radios, 3 servos of the swash plate all moving up and
down together for cyclic and moving differentially for cyclic. My newer
electric heli's have this but not my glow fuel collection.

I found this on Tom Ingram:
http://www.cs.iit.edu/~amadist6/CM/c...masIngram.html

They don't hardly make em like that anymore, now it's buy a RTF or ARF, slap
together and fly. I don't fly much anymore except for micro electrics
around the house or field across the street.

RogerN

"RogerN" fired this volley in
m:

They don't hardly make em like that anymore, now it's buy a RTF or
ARF, slap together and fly. I don't fly much anymore except for micro
electrics around the house or field across the street.


I've built a few from true scratch, but I only have time for kits now.
(well, not even for that presently)

I've still got two un-built kits and a half-dozen rolls of MonoCote on
the shelf. True "kits", not ARFs.

I have to get past a big project I'm on, then I'll spring free enough
time to put together that 3-meter sailplane I've been wanting to build.
It has one of the high-efficiency Selig airfoils that's supposed to give
it high 'heavy' speed and good lift at low speeds and lightly-loaded.

I've got enough land for a winch start if I want, but I'm partial to the
extra difficulty of getting it up and keeping it up on a high-start. I
started out on the Goldberg 'Gentle Lady' sailplanes, and kept working
up. 'Even built a "Gutsy Lady" with a spar that would support 60lb at
the center of two meters without breaking, and only added about 7 oz to
the all-up weight.

I've got a few stink-pots in the barn, too, including an old fave' Ugly-
Stick that I took out all the dihedral on the wings... so it'll stay in
any attitude you put it in, all the way to the ground!

Lloyd

"Ed Huntress" wrote in message
...

On Fri, 20 Sep 2013 19:41:27 -0500, "RogerN"
wrote:

snip

Why do you need a stronger epoxy for an .049 engine?

I don't know if you do. I was commenting on JB Weld. It's good stuff
that solves a lot of problems, but I've heard from many people who
think it's a "strong" epoxy. It's not. It's run-of-the-mill in the
strength department. Elmer's two-part epoxy probably has the same
strength.

What I was calling "strong" is relative to what's commonly available. In
hobby shops and local stores the 2-Ton epoxies are about as strong as I've
found. So what's with the strong epoxies and why aren't they readily
available in stores? I'm guessing either expensive or dangerous, still it
would be nice to have stronger options where the others don't hold.

The engines on my R/C
helicopters include .60 2-stroke and .90 4-stroke and I've never had a
drive
shaft failure from JB-weld of the fittings in the tail rotor drive shaft.
My tail rotor blades are around 10-12" swing with variable pitch, the
models
are 10-11lbs, they shake if out of balance, still the JB-Weld or other
4000PSI epoxy has never failed, the shafts get destroyed in a crash but
never had an epoxy failure so far. I haven't had that good of luck with 5
minute epoxy.

No surprise. Five-minute epoxy is very compromised for the sake of the
quick cure. It's weak, it can be brittle (depending on brand and
formulation), and it's usually not even waterproof. A standard
slow-cure, room-temperature cure, amine-cure epoxy is very waterproof.

I've had 5-minute epoxy fall apart after a few years, the nitro-methane in
the fuel seems hard on a lot of things, not sure about 5-minute epoxy.

Note my drive shafts are supported at each end, I'm not sure
I'd want a 5" extension on an .049 without support. Also my tail rotor
shafts aren't close to the engine so there is no high temperature problem,
I
doubt an 049 would get very hot on the shaft, never had problems with
props
melting or anything like that.

On a side note, some have had problems with the muffler coming loose on
the
4-stroke engines, they use JB-weld and it holds up on the exhaust pipe of
the model engines.

RogerN

Roger, I'm just telling you what the measured properties of those
materials are. They're well-known in the adhesives field. I wrote a
12-page report on them years ago for American Machinist, but these
basic epoxies haven't changed. They've been the same materials since
the '60s.

JB Weld's metal filler probably provides some advantages in a variety
of situations. Bond strength is just not among them. And the ability
of amine-cured epoxies to tolerate high temperates doesn't vary much
among brands.

--
Ed Huntress

Thanks, great information to have, it's good to know there are stronger
epoxies that the hobby shops don't sell. Any info on the stronger epoxies,
where to get, PSI strength, etc.?

RogerN

On Fri, 20 Sep 2013 19:17:47 -0400, Ed Huntress
wrote:

...

JB Weld is not a strong epoxy. It's an ordinary amine-cure epoxy
that's filled with steel powder, and its strength is typical -- less
than 4,000 psi under ideal conditions.

They make some wild temperature claims for it, but my guess is that
they're talking about the temperature at which it breaks down and
begins to carbonize -- 550 deg. F. It's lost all useable strength long
before you reach that temperature.

JB Weld outperforms West System where high temperatures are concerned.
OTOH if I understand the question I would also vote for the 6xx
retaining compounds (Vibratite make Loctite equivalents and are
cheaper). One thing to note: They hold differently on different
metals, e.g some are weaker on brass than on steel. The data sheets
are useful here.

Michael Koblic,
Campbell River, BC

On Sun, 22 Sep 2013 21:28:58 -0400, Ecnerwal
wrote:

In article ,
Tim Wescott wrote:

This is out of curiosity:

How good of a bond can one achieve with epoxy to aluminum? How good can
one achieve with epoxy that ordinary folks can mail-order, vs. what folks
who have the ear of a Locktite sales rep and applications engineer can
achieve? How good can one achieve with JB Weld?

Armstrong A-12 is moderately available to the determined consumer last I
checked. Has the interesting property of variable hardness with mix
ratio. I stuck together some serious stuff with it that couldn't be
bolted for electrical reasons, and was then subjected to serious forces
by electro-magnetic means, back when Ronnie was Ray-Gunning. Of course,
the Mech-E specified the areas of the joints to be sufficent. Heat cure
or a LOT of patience (= heat cure.) 5KSI at 1:1 mix.

Plastic titanium (Devcon) supposedly can do 18KSI. Probably compressive.
Nah, they lowered the claim to 15K since I bought mine, and it's only 2K
tensile/shear.

Plastic aluminum (liquid, also devcon) 2.7 tensile shear, 9Ksi
compressive - paste a bit worse.

A-12 is winning so far.

Possibly an "aluminum solder" would be better - I'm not sure. The "high
strength" stuff is basically zinc, but I've struck out finding a tensile
strength for zinc so far.

http://www.belmontmetals.com/datasheets/L-1014.pdf

Hm - the tensile strength for this process I did find some data for and
Al-Al joints is under 1KSI, but that's Sn/Ag solder.

http://www.superiorflux.com/papers/D...lder_Paste.pdf

Perhaps give A-12 a try.

http://www.ellsworth.com/armstrong-a...50ml-mixpac-ca
rtridge/?gclid=CKrblpuu4LkCFZSd4Aod-CYAXg


A4 Metalset is speced for aviation uses. It looks like JB Weld..but
is supposed to be much tougher.

I installed a Night Sun on a Ranger helicopter and used A4 for most of
the cockpit attachments




"The socialist movement takes great pains to circulate frequently new labels for its ideally constructed state.
Each worn-out label is replaced by another which raises hopes of an ultimate solution of the insoluble basic
problem of Socialism, until it becomes obvious that nothing has been changed but the name.
The most recent slogan is "State Capitalism."[Fascism] It is not commonly realized that this covers nothing more
than what used to be called Planned Economy and State Socialism, and that State Capitalism, Planned Economy,
and State Socialism diverge only in non-essentials from the "classic" ideal of egalitarian Socialism. - Ludwig von Mises (1922)

"RogerN" wrote in message
m...
"Ed Huntress" wrote in message
...

On Fri, 20 Sep 2013 19:41:27 -0500, "RogerN"
wrote:

snip

Why do you need a stronger epoxy for an .049 engine?

I don't know if you do. I was commenting on JB Weld. It's good stuff
that solves a lot of problems, but I've heard from many people who
think it's a "strong" epoxy. It's not. It's run-of-the-mill in the
strength department. Elmer's two-part epoxy probably has the same
strength.

What I was calling "strong" is relative to what's commonly available. In
hobby shops and local stores the 2-Ton epoxies are about as strong as I've
found. So what's with the strong epoxies and why aren't they readily
available in stores? I'm guessing either expensive or dangerous, still it
would be nice to have stronger options where the others don't hold.

The engines on my R/C
helicopters include .60 2-stroke and .90 4-stroke and I've never had a
drive
shaft failure from JB-weld of the fittings in the tail rotor drive shaft.
My tail rotor blades are around 10-12" swing with variable pitch, the
models
are 10-11lbs, they shake if out of balance, still the JB-Weld or other
4000PSI epoxy has never failed, the shafts get destroyed in a crash but
never had an epoxy failure so far. I haven't had that good of luck with
5
minute epoxy.

No surprise. Five-minute epoxy is very compromised for the sake of the
quick cure. It's weak, it can be brittle (depending on brand and
formulation), and it's usually not even waterproof. A standard
slow-cure, room-temperature cure, amine-cure epoxy is very waterproof.

I've had 5-minute epoxy fall apart after a few years, the nitro-methane in
the fuel seems hard on a lot of things, not sure about 5-minute epoxy.

Note my drive shafts are supported at each end, I'm not sure
I'd want a 5" extension on an .049 without support. Also my tail rotor
shafts aren't close to the engine so there is no high temperature
problem, I
doubt an 049 would get very hot on the shaft, never had problems with
props
melting or anything like that.

On a side note, some have had problems with the muffler coming loose on
the
4-stroke engines, they use JB-weld and it holds up on the exhaust pipe of
the model engines.

RogerN

Roger, I'm just telling you what the measured properties of those
materials are. They're well-known in the adhesives field. I wrote a
12-page report on them years ago for American Machinist, but these
basic epoxies haven't changed. They've been the same materials since
the '60s.

JB Weld's metal filler probably provides some advantages in a variety
of situations. Bond strength is just not among them. And the ability
of amine-cured epoxies to tolerate high temperates doesn't vary much
among brands.

--
Ed Huntress

Thanks, great information to have, it's good to know there are stronger
epoxies that the hobby shops don't sell. Any info on the stronger
epoxies, where to get, PSI strength, etc.?

RogerN

The consumer grade epoxies are a compromise between being strong and being
idiot proof.
The higher strength ones are not trying to achieve a 1:1 mix ratio and are
usually pretty sensitive to variations in the ratio. Typically, they have
2:1 to 10:1 ratios. You can't just squeeze two ribbons out and mix. Usually
you have to mix up a large enough batch to guarantee a proper mix regardless
of how big the job is.

They come in Quarts and have a shelf life. Some companies have special
syringe dispensers in the proper ratio but they use a special gun and a
mixing tube.
All of this is tough on your average consumer.

Paul K. Dickman

On Sat, 21 Sep 2013 12:51:15 -0400, Ed Huntress wrote:

On Sat, 21 Sep 2013 11:12:04 -0500, Tim Wescott
wrote:

On Sat, 21 Sep 2013 00:05:25 -0400, Ed Huntress wrote:

Note my drive shafts are supported at each end, I'm not sure
I'd want a 5" extension on an .049 without support. Also my tail
rotor

I'd planned on a bearing at the far end, and a U-joint (ball and pin,
like on a model boat) at the near end.

That was Roger, not me. I'm the glue guy, not the model guy. g

Roger has exceeded my (political post)/(useful post) ratio on this group,
in spite of having posted useful stuff. I have regretfully plonked him.

I think there's a time limit on it, so if he's better when Pan turns his
posts back on, I'll not plonk him again.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

On Sat, 21 Sep 2013 17:17:13 -0400, Tom Gardner wrote:

On 9/20/2013 3:03 PM, Tim Wescott wrote:
This is out of curiosity:

How good of a bond can one achieve with epoxy to aluminum? How good
can one achieve with epoxy that ordinary folks can mail-order, vs. what
folks who have the ear of a Locktite sales rep and applications
engineer can achieve? How good can one achieve with JB Weld?
snip

Everybody here has stayed on the adhesive train! I say use a mechanical
solution. Pin or swage it together!

Good thought, but:

If I did this I'd be using relatively thin wall tubing; pinning would
either rip out, or require me to use thicker tubing than I want.

Swaging would, I'm pretty sure, vibrate off as the tubing stretched.

Shrinking the tubing onto the end, followed by shrinking a collar on,
might work -- but that's extra weight, and I think I'd rather try glue.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

In article ,
Tim Wescott wrote:

This is out of curiosity:

How good of a bond can one achieve with epoxy to aluminum? How good can
one achieve with epoxy that ordinary folks can mail-order, vs. what folks
who have the ear of a Locktite sales rep and applications engineer can
achieve? How good can one achieve with JB Weld?

Armstrong A-12 is moderately available to the determined consumer last I
checked. Has the interesting property of variable hardness with mix
ratio. I stuck together some serious stuff with it that couldn't be
bolted for electrical reasons, and was then subjected to serious forces
by electro-magnetic means, back when Ronnie was Ray-Gunning. Of course,
the Mech-E specified the areas of the joints to be sufficent. Heat cure
or a LOT of patience (= heat cure.) 5KSI at 1:1 mix.

Plastic titanium (Devcon) supposedly can do 18KSI. Probably compressive.
Nah, they lowered the claim to 15K since I bought mine, and it's only 2K
tensile/shear.

Plastic aluminum (liquid, also devcon) 2.7 tensile shear, 9Ksi
compressive - paste a bit worse.

A-12 is winning so far.

Possibly an "aluminum solder" would be better - I'm not sure. The "high
strength" stuff is basically zinc, but I've struck out finding a tensile
strength for zinc so far.

http://www.belmontmetals.com/datasheets/L-1014.pdf

Hm - the tensile strength for this process I did find some data for and
Al-Al joints is under 1KSI, but that's Sn/Ag solder.

http://www.superiorflux.com/papers/D...lder_Paste.pdf

Perhaps give A-12 a try.

http://www.ellsworth.com/armstrong-a...50ml-mixpac-ca
rtridge/?gclid=CKrblpuu4LkCFZSd4Aod-CYAXg

--
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.

On 9/22/2013 6:10 PM, Tim Wescott wrote:
On Sat, 21 Sep 2013 17:17:13 -0400, Tom Gardner wrote:

On 9/20/2013 3:03 PM, Tim Wescott wrote:
This is out of curiosity:

How good of a bond can one achieve with epoxy to aluminum? How good
can one achieve with epoxy that ordinary folks can mail-order, vs. wh
folks who have the ear of a Locktite sales rep and applications
engineer can achieve? How good can one achieve with JB Weld?
snip

Everybody here has stayed on the adhesive train! I say use a mechanical
solution. Pin or swage it together!

Good thought, but:

If I did this I'd be using relatively thin wall tubing; pinning would
either rip out, or require me to use thicker tubing than I want.

Swaging would, I'm pretty sure, vibrate off as the tubing stretched.

Shrinking the tubing onto the end, followed by shrinking a collar on,
might work -- but that's extra weight, and I think I'd rather try glue.


I see.

On Tue, 24 Sep 2013 17:33:20 -0400, Tom Gardner Mars@Tacks wrote:

On 9/22/2013 6:10 PM, Tim Wescott wrote:
On Sat, 21 Sep 2013 17:17:13 -0400, Tom Gardner wrote:

On 9/20/2013 3:03 PM, Tim Wescott wrote:
This is out of curiosity:

How good of a bond can one achieve with epoxy to aluminum? How good
can one achieve with epoxy that ordinary folks can mail-order, vs. wh
folks who have the ear of a Locktite sales rep and applications
engineer can achieve? How good can one achieve with JB Weld?
snip

Everybody here has stayed on the adhesive train! I say use a mechanical
solution. Pin or swage it together!

Good thought, but:

If I did this I'd be using relatively thin wall tubing; pinning would
either rip out, or require me to use thicker tubing than I want.

Swaging would, I'm pretty sure, vibrate off as the tubing stretched.

Shrinking the tubing onto the end, followed by shrinking a collar on,
might work -- but that's extra weight, and I think I'd rather try glue.


I see.
Shrink and shrink means no clearance, which means STRAIGHT.

A glued high speed shaft seems a bit dicey to me, balance-wise.

On 9/24/2013 9:03 PM, wrote:
On Tue, 24 Sep 2013 17:33:20 -0400, Tom Gardner Mars@Tacks wrote:

On 9/22/2013 6:10 PM, Tim Wescott wrote:
On Sat, 21 Sep 2013 17:17:13 -0400, Tom Gardner wrote:

On 9/20/2013 3:03 PM, Tim Wescott wrote:
This is out of curiosity:

How good of a bond can one achieve with epoxy to aluminum? How good
can one achieve with epoxy that ordinary folks can mail-order, vs. wh
folks who have the ear of a Locktite sales rep and applications
engineer can achieve? How good can one achieve with JB Weld?
snip

Everybody here has stayed on the adhesive train! I say use a mechanical
solution. Pin or swage it together!

Good thought, but:

If I did this I'd be using relatively thin wall tubing; pinning would
either rip out, or require me to use thicker tubing than I want.

Swaging would, I'm pretty sure, vibrate off as the tubing stretched.

Shrinking the tubing onto the end, followed by shrinking a collar on,
might work -- but that's extra weight, and I think I'd rather try glue.


I see.
Shrink and shrink means no clearance, which means STRAIGHT.

A glued high speed shaft seems a bit dicey to me, balance-wise.


I just have the mechanical gene when it comes to fastening. Not that
adhesives don't have their place, but moving parts have a whole set of
dynamics on a joint that adhesives alone will eventually fail...in my
world. For this application, I think that maybe a mixture of adhesives
and mechanical fastening would work.

On Friday, September 20, 2013 12:03:50 PM UTC-7, Tim Wescott wrote:
This is out of curiosity:



How good of a bond can one achieve with epoxy to aluminum? How good can

one achieve with epoxy that ordinary folks can mail-order, vs. what folks

who have the ear of a Locktite sales rep and applications engineer can

achieve? How good can one achieve with JB Weld?



An Internet acquaintance has a scale model airplane that needs a

driveshaft driven by an 049 engine (that's a bitty one that swings a 5"

prop, not a humongous one that swings a 12" prop -- 1/20th cubic inch,

not 1/2). His current driveshaft uses a solid aluminum rod, and is

heavier than he'd like.



Because of the way the plane balances with the current shaft, every gram

he takes out of the shaft takes out more than two grams from the plane,

because he's currently got a buttload of weight in the nose.



I'm thinking that one could machine ends out of aluminum, then plug them

into a thin-wall (.035"), 1/2" or 5/8" diameter tube made of 2024. I'm

also thinking that bonding everything with epoxy would be a valid way to

go -- but I'm not so sure about the epoxy in a part that's going to be

subject to lots of vibration in at least eight of the six available

degrees of freedom.



Threading such thin wall tubing makes me think that it'll just break.



Welding makes me think it'll never happen.



Soldering???



--



Tim Wescott

Wescott Design Services

http://www.wescottdesign.com

A little late but I would go with 6061 and have the assembly
dip brazed. Maybe too costly...

In article ,
wrote:

On Friday, September 20, 2013 12:03:50 PM UTC-7, Tim Wescott wrote:
This is out of curiosity:



How good of a bond can one achieve with epoxy to aluminum? How good can

one achieve with epoxy that ordinary folks can mail-order, vs. what folks

who have the ear of a Locktite sales rep and applications engineer can

achieve? How good can one achieve with JB Weld?



An Internet acquaintance has a scale model airplane that needs a

driveshaft driven by an 049 engine (that's a bitty one that swings a 5"

prop, not a humongous one that swings a 12" prop -- 1/20th cubic inch,

not 1/2). His current driveshaft uses a solid aluminum rod, and is

heavier than he'd like.



Because of the way the plane balances with the current shaft, every gram

he takes out of the shaft takes out more than two grams from the plane,

because he's currently got a buttload of weight in the nose.



I'm thinking that one could machine ends out of aluminum, then plug them

into a thin-wall (.035"), 1/2" or 5/8" diameter tube made of 2024. I'm

also thinking that bonding everything with epoxy would be a valid way to

go -- but I'm not so sure about the epoxy in a part that's going to be

subject to lots of vibration in at least eight of the six available

degrees of freedom.



Threading such thin wall tubing makes me think that it'll just break.



Welding makes me think it'll never happen.



Soldering???



--



Tim Wescott

Wescott Design Services

http://www.wescottdesign.com

A little late but I would go with 6061 and have the assembly
dip brazed. Maybe too costly...

There are airplanes made of glued aluminum alloy. It's quite a
process, but for a model airplane one can use a slow-curing epoxy cured
at 180 F.

Clean the surfaces to be glued *very* well, to eliminate all grease and
wax, and the surface oxide. I'd use wet/dry sandpaper in windex, or
the like. Like real TSP from the paint store.

Beware acetone - most has some oil in it.

Design the assembly do the gluelines are in shear, not peel. Do not
expect butt joints to work.

Joe Gwinn