details of the types of epoxy used in different applications. The Lotus glue is an odd one, a heat cured epoxy. That wouldn't work for large aircraft. The Wings on most modern aircraft are bonded using an epoxy-polysulphide adhesive (I think, but I'm not sure).
Yes, called the "chicken rivet".
Fascinating article.
Most glues are good in shear, bad in peel..that's why tenoned joints are used..
It would be overkill for your purposes, but the one I have used is an ITW Plexus epoxy-type resin specially formulated for aluminium
Simple lap joint in aluminium sheet - the aluminium fails before the joint.
Probably best bet for small quantities is a yacht chandler.
You don't have an ideal situation if you're trying to glue a flat boss to a round tube, especially with such a thin wall thickness because you can't even flat the tube enough to match the boss without breaking right through it. You could shape the boss to match the tube o/d if you had a lathe or mill to generate a 70mm diameter curve. Easier to weld it then I'm now thinking.
If I was doing it I'd flat the tube a bit with a milling cutter, drill a hole, turn the boss to be a fit into that with a flange and weld round it. Alternatively I'd set up a flycutter at 70mm diameter, radius the bottom of the boss to match the tube and then weld that on. I'll do it for you if you get stuck. I've got loads of spare ally offcuts too if you need to make another one.
Alternatively, glue the boss to the inside and then tightening the sensor will just make the joint compress more.
I've cut a hole in the tube so the boss pokes through.
Rather beyond the facilities of my home workshop.;-)
Looking at my Haynes welding manual, they make a big song and dance about MIG ally welding. Talk about needing a special wire liner. Preheating the work to 350 degrees.
I've glued it in place with ordinary superglue - and it seems pretty solid. Tightened the sensor as much as I would normally do and it held.
Araldite went out of favour before 1978 when I transfered within the aerospace industry. What followed was a product called hysol. This was available as an adhesive and a liquid shim. Liqid shim had powdered slate, or powdered aluminium mixed in, to give it more body.
Both Araldite and hysol depended on the same thing, they had to be used on aluminium that had been anodised and epoxy primered. The bond to the ally and paint was 100% and the weak point was the bonding agent itself. I have seen many joints that have failed and it has always been the bonding agent and not the paint. I think others have pointed out the problems with a bare aluminium bonded joints.
(Just got back from 2 long drives, brain is about as much use as a bowl of mashed potato at the moment)
So going back to Dave's problem, I would say weld, braze, or solder, for a long joint life.
Dave
I've got the equipment to do any of these, but not the experience. I've tried ally soldering ages ago - stuff bought from Maplin - without success. Welding always has the danger of burning through with thin material. Brazing sounds more like it - but what is used?
The phrase epoxy-polysulphide doesn't hold up with me, though I could be wrong, as I have been out of it for ten years now.
Epoxy suggests a 2 part mix, like Araldite.
Polysulphide suggests a 2 part mix that produces a synthetic rubber type mix. A company that makes this is called Thiokol.
If an aircraft wing is not made of carbon fibre, then the aluminium is joined using an interfay that is defined by the manufacturer. This can be all sorts of things, but the cabin skins are usually interfayed with one of the polysulphide compounds to prevent cabin pressure losses. This is like joining the various skins with a water proof, air tight seal.
Take a close look at any aircraft and you will see that it is a patchwork quilt of skins, rivetted to the cabin stringers and stations. The stations being the frames that form the shape of the diam. of the fusalage.
The size of the skins is down to the time that the interfay is applied, to the final rivet goes in to that skin. Before the interfay goes beyond workability.
Dave
While doing a bit of Googling about aluminium brazing, came across this:-
I have had complete success with soft solder and Carrs aluminium flux. I got it from a model train place in Raynes Park IIRC.
They also sold aluminium solder, but I never found it particularly good. I used resin cored electrical lead/tin.
DO NOT inhale flux fumes. They are vile and lead to 2 days of cold//flue like symptoms.
Do it outside.
Oh, here you go
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