If it has to be glue rather than solder then use epoxy but make sure the
surfaces are completely clean and don't touch them between cleaning and
applying the adhesive. If you can heat the parts to about 100C for an hour
or so once the epoxy has initially hardened, then the joint wil be even
stronger. Adhesive jointing is even more sensitive than soldering to
About 60% of the skin of a Boeing 747 is held together by adhesive bonding -
Normally I'd solder it in place ( silver solder for strength, soft for
a quick job ) - but if access is limited or the application of heat
might damage something you might try JB Weld ( a sort of tough epoxy
I used this stuff to stick a brass tube filled with wadding onto the
cover of my Land Rover's Fairey overdrive - the vent hole would spray
out a fine mist of gear oil which eventually ended up all over the
rear of the vehicle. It stayed put for years and eventually had to be
knocked off with a hammer when the overdrive was removed.
Stephen Howard - Woodwind repairs & period restorations
....except that, if it's 'new technology', they'll perhaps be anxious
to keep it a bit on the over-engineered side until it's been proved in
service. They wouldn't want a Comet-style series of failures.
I thought I had read somewhere, a few months ago, that the project was
a bit behind schedule because they were having to sort out issues with
the attachment of wings to fuselage.
Tony Jeffree Wrote:
> On Tue, 29 Jul 2008 23:24:22 GMT, email@example.com wrote:
It's a little more complicated than that.
Both the Boeing and the Airbus wings have been tested far beyond the
stress expected on the wings, more or less the point where
either the wing, the
fuselage or the passengers would have failed.
If I remember correctly the safety factor is Maximum *1.5. The Airbus
failed at around the critical point (actually slightly below it
but within 3%)
The Airbus wing flexed 7.4 metres before rupturing.
I remember reading somewhere (High Performance Composites?) that a
had had a similar failure.
The design problem is enormous, whereas one can look as a piece of
a single piece, the equivalent composite part may be
mutiple layer of a material
in a matrix . Each layer may be laid at a
different angle and where the material
is woven, there is a stress point
whereever one thread crosses another.
So instead of the fairly precise data that is available to the metal
one has to work with approximations of behaviour.
Another problem is that effectively you 'create' the material every
make a component part. Imagine if you had to mix, melt, roll
and treat and test
every piece of aluminium instead of relying on the
manufacturer to do so. Indeed
the Americans have the AGATE database
which defines how to put the various
materials and resins together to
make a standard material and the various
figures that one can use for
that material to avoid some of the problems.
So 'overengineered' is a relative term, given the large variables
the many modes of failure that have been identified.
I've seen video of composite wings being laid up. They use a big CNC
device which applies the fabric in strips in a certain pattern. The
machine lays down the fabric remarkably fast. The angle of the fabric
changes depending on which layer it is and where on the wing it is. So
the effector at the end of the arm applying the fabric is constantly
turning. 5 degrees of freedom, or maybe 6. There are the X,Y,&Z axes
along with roll and yaw. Maybe tilt too. And different weaves are used
also. Must be hard to get all the bugs out the first time.
If you are not confident to solder, have you consideed solder paint.
This is a very useful mix of powered solder and flux, you just brush
on the prepared surfaces and heat till the solder melts. It is not too
good at gap filling but at least it will tin the surfaces ready for
Cup alloys (NCEASC) sell it in little pots quite cheaply., other
suppliers you will have to check that they are not selling you
"soldering paste" which is often just a flux.
Thanks for all the info, chaps. I went with Araldite, when it's set I'll
it a whirl and see how things hold up. I'll look into the solder
stuff and maybe
have a practise on some scrap.
The "thing" was just a clamping plate, steel to steel and I wanted a
brass inbetween to avoid too much marking of surfaces. Will there
friction between brass and steel than there would be between
steel and steel?
Unlike surface materials do something friction-wise,
but I can't remember what!
There will be less - see:
Steel to Steel coeff 0.8, steel to brass 0.35 for dry surfaces.
However, much less and almost the same if grease/oil is present.
I would suspect the coeff. will be less for "engraving brass"/steel.
(i.e., leaded brass, as used in clockmaking).
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