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If you make an airframe using chrome-moly tubing, you make the joints between lengths by welding, either oxy or TIG/MIG.  Making the airframe using aluminium, such as with the Morgan Cheetah, involves the use of pop rivets to join the lengths using web plates. That's a lot of work, first in making the web plates, then drilling the holes for the rivets in both the plates and the tubing, and finally doing the riveting. What if you could make the joints by welding?

 

Now aluminium welding is nothing new. Aluminium welding is something that requires some expensive equipment, AND you should use a welding glass in your helmet that is specifically designed to give a clear view of the work by filtering out the wavelengths of the aluminium light spectrum. There is a product available that allows you to weld join aluminium using a propane torch and special rods. The process is virtually the same as soldering, and needs no other personal protection equipment than safety glasses, gloves and the type of clothes you would wear when soldering.

 

The product is called aluminium welding rod. Here is a video which shows what can be done with these rods. When you open the link, just watch the first video.

 

https://www.toolking.com.au/aluminium-and-cast-alloy-repair-rods-ultra-bond-5pc-pack-brazing-soldering-welding/

 

We all know that videos by the seller can be a bit suspect, so here are two made by blokes who have used these rods.

 

 

 

Here is a link to one Australian manufacturer of these rods. https://www.toolking.com.au/aluminium-and-cast-alloy-repair-rods-ultra-bond-5pc-pack-brazing-soldering-welding/

 

The business is in Bathurst, so talking to them should be easy.

 

DISCLAIMER:

 

I found these guys while searching the 'Net after a friend of mine told me about these rods. Tool King doesn't know me and I don't get a brass razoo for posting the link.

 

Old Man Emu

 

 

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 You can't weld .015" sheet and any sheet welding will buckle,  no matter how good you are at it. Spot welding of steel sheet is used widely in auto work but not on a surface you see without dolly work which is time consuming and requires  skill.  You also get stresses with welding you don't get with riveting  CAD drilling and riveting makes a jig unnecessary. Some alu laps are glued/bonded and some riveted ones also. That makes the lap take the stresses over a larger area,& stops corrosion in the lap .  Liberty Ships were welded and often broke apart in rough seas. Maybe some better techniques today make it more possible but I don't know for sure. Nev

 

 

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Welding can result in damage to the metal structure just alongside the weld, which leads to cracking and worse. If I remember correctly Murphy made at least one airframe out of tube and special extruded joiners that were rivetted.

 

Even steel fuselages need heat treatment sometimes to get rid of stresses built into the welded frame.

 

 

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I love the way people come in on a topic obviously without taking the time to review the material in the post. It took a lot of time to search for information on this topic and to present it in a clear an comprehensible way. 

 

Did Facthunter and Yenn even bother to investigate the links I provided? I very much doubt it. At no time, apart from initially referring to how chrome/moly tubing is joined, did I mention welding sheet metal or dealing with destressing areas where heat had been applied in the course of welding. I even mentioned that heat welding of aluminium is difficult and apart from learning to control the weld, people doing aluminium welding require a special formulation in their welder's helmet lens.

 

 

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1. There's nothing wrong with welding, if the correct materials, the correct welding rods, and the correct processes are followed. Welding has a habit of inducing stresses in the structure, and these stresses must be addressed - either by the structure being held in a jig to prevent distortion, or by post-heat-treating of the welded area, to relieve welding stresses. Welding of heat-treatable materials is quite involved, and must follow the manufacturers specific (post-welding) heat-treating process.

 

Many (aluminium and steel) materials are quite tolerant of welding stresses - but you must know the particular qualities of the material you're working with, prior to carrying out welding.

 

2. Rivets and plating are a simple design that has stood the test of time - although they are relatively labour-intensive. Rivets and plating usually lend themselves to somewhat easier repair in the case of damage.

 

3. As regards the Tool King aluminium welding rods - these have been around for maybe 40 years or more. They usually turn up at shows, demonstrations, field days, and other events where a crowd offers potential for sales.

 

They're usually sold by the regular suspects - those same blokes who sell innovative vegetable peelers and slicers, limb trimmers, magic hammers, and the thousand and one other wondrous devices, we never knew we couldn't live without.

 

Naturally, most of these devices and tools come with the steak knives offer, if you buy two sets of the product - at inflated prices, as you usually find out later.

 

I can recall these aluminium welding rods being touted at these events, as God's gift to DIY'ers who were born with two left thumbs, and who could normally injure themselves with a rubber sword.

 

I was actually one of the gullible public who bought some of these rods, after watching the appointed guru weld up a torn Coke can, with what appeared to be consummate ease.

 

Alas, whenever I tried to weld any form of aluminium with these rods, my attempts were as dismal as anyones first attempts at welding aluminium, without some form of protective gas covering the weld area.

 

They are basically useless - the biggest con around - because no-one, no matter what fancy aluminium rods they possess, can simply weld aluminium without extensive cleaning and preparation of the weld area, which prep work also involves heating the area surrounding the area to be welded - particularly if there is a difference in the two material thicknesses being welded. And you need the inert gas shield, of course.

 

Those rods still sit in one of my cabinets and they will probably remain there for all time, as they are next to useless - unless you need to weld up Coke cans, of course.

 

I recently knocked up an aluminium bullbar for my 5 tonne Isuzu truck. I don't have a TIG welder, I hate working with aluminium because of its peculiar characteristics when being welded and heated - although I can stick virtually any other metal together with ease.

 

For my bullbar, I employed a local bloke, an Italian gent who does TIG welding as a spare-time earner from his regular job, as an aluminium welder. He rolled up with his TIG setup in his van, and I assisted in setting up the various aluminium parts and preheating where needed (on most of the bar), and he did some excellent aluminium welding work, for which I was happy to pay him. We didn't do any stress-relieving heating, because the aluminium we used, is quite tolerant to welding stresses.

 

 

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I'm sorry I didn't address exactly what you wrote OME. My comment s are general but I HAVE run a welding business and have friends who have exotic tickets to weld stuff for the Military.  with the gear for all materials

 

I've used a DILLON torch and the low Temp (almost solders) and re done them with TIG later widshing I'd done it hte right way the firsat time.. My comments were GENERAL and I believe valid. I'm very time constrained at times so I can't just address every point nor will I try to. I'm very sceptical of anything I don't see being done in high quality welding processes  in/by the very up to date people I know. Some stuff I have to get welded is irreplaceable so I'm not inclined tpo experim,ent with that kind of article. Welding also upsets any heat treatment of aluminium already done. Nev

 

 

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As Onetrack mentions, those rods are pretty much rubbish, they are as mentioned, like aluminium soldering.

 

Aluminium welding is fine if a process is followed, re; re-heat treatment, or enough additional area that the softened area meets the strength of the original material. 

 

Motocross bikes have been using thin gage aluminium welding for decades now under severe punishment, and have lasted just fine, besides all the dire internet predictions. But they go through a re-heat treatment process that simply isn't available easily to the homebuilder, and then there's repairing damage later ...

 

You could consider gluing, but that's a bit of a process too, also involving a big  oven, Google Lotus Elise chassis development.

 

As pain in the azz as it is, there's sound practical reasons that we still rivet, and I would for one who drilled another 2000 rivet holes just yesterday, like to find that magic replacement, and I have looked.

 

 

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I love the way people come in on a topic obviously without taking the time to review the material in the post. It took a lot of time to search for information on this topic and to present it in a clear an comprehensible way.

 

 I even mentioned that heat welding of aluminium is difficult and apart from learning to control the weld, people doing aluminium welding require a special formulation in their welder's helmet lens.

 

Have done some aluminium mig  and tig welding. I have not heard of using special formulation in the helmet lens however the gas diffuser on a tig torch can be called a lens and aluminium requires different gas than steel.

 

I also have bought the field day magic aluminium brazing rods, could not get them to weld anything.

 

Based on my experience I would like my aluminium aircraft to be (solid) riveted together.    

 

 

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I owned an Aluminium fabrication business for a few years. Our products were mainly gates and panels, balustrading etc where there was not much stress placed on the product but it also had to look good so joins were chamfered and the MIG welds ground down and polished to provide a seamless profile and the product powder coated. I never had a single failure or return from a customer. All the aluminium joins on my Sierra airframe are done with gussets and blind rivets  (except the main spar which has solid rivets). It didn't take long to cut up heaps of gussets and then drill & rivet them in situ on the bench.

 

 

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I have a feeling that poor results from this product are due to failure to follow manufacturer's instructions.

 

I'm not giving up this fight yet. I'm going to get in touch with the mob at Bathurst and go right into the product. If I'm wrong, I will apoligise. If not, ....

 

Watch this space.

 

 

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A more concentrated heat source would have probably aided in the guys you tube vid to heat exactly where he needed it to be. That blanket heating of a MAP torch is not really suitable. I have a nice tig that with lots of practice I am starting to weld better. It won’t happen first time. I have spent hours watching a Lame mate welding for me and talking me through process.  There are Tig welders out there cheaper now than ever before. It just takes more practice with them to learn the perfect settings for each job. I have a henrob torch that I first bought due to the field days demo, but far more tricky to learn on than TIG.

 

 

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I must admit that I didn't look at all the info from OME, but I think what I said still stands. Their welding looks to me to be more like soldering, in one of the videos they got a blob, than a run of matal, but had to weld the other side. They made the molten rod run between the two pieces, in just the same way as solder is wicked in.

 

I certainly would not fancy being the test pilot of a plane with a fuselage frame built using this method.

 

Aluminium is way beyond my ability to weld and I have seen expert welders have failures. When I was in the business of designing things, we used to make the design to suit the method of onstruction. Ladders used to have holes in the styles for the rungs to go through and then be welded on both sides of the style. We learnt that lesson from the failure of rungs to be welded to the style with no locating support.

 

I hope you can find out a way to make this feasible for aircraft manufacture OME

 

 

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hope you can find out a way to make this feasible for aircraft manufacture OME

 

I'm thinking of making up three test pieces in the shape of the letter 'I", on other words, two horizontals joined by an upright. 

 

One piece will be joined together using these rods. A second will be the riveted gusset method, and the third will be welded by a mob who make truck bodies and trailers.

 

After I get the pieces made up I hope to subject them to a test of the joint strength by attaching them to a hydraulic ram and pulling on them to see how much pressure (force/unit area) all the joints can handle before something happens. The ram I could use has a surface are of one square inch, so the force will be reported in lbs/sq.in. I will have to do some calculations to determine the actual surface area involved in the several joints.

 

 

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Sounds good, but don't forget that it will not allow for fatigue, which is one of the expected fail points of a welded joint.

 

Somebody else mentioned glued joints. Not easy with aluminium, but I did one years ago and it knocked around for ages, never did give way, but I don't know where it is now.

 

I cleaned all the faying surfaces, then used a scotch brite pad, coated with epoxy glue, to give a final cleaning and spread glue to stop oxidisation.

 

 

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Really, how often does one see fatigue cracks in tube airframes? I must talk to a bloke I know who's the holder of an aviation welder's licence to discuss weld strength.

 

Looks like I've given myself a hefty project for this Summer.

 

 

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people doing aluminium welding require a special formulation in their welder's helmet lens.

 

This is the link to the site of the guy who has developed the special lens for aluminium welding. I've watched welding being done through one of these lenses and the comparison with a normal welding lens is well in favour of the TM 2000 lens.

 

https://www.tinmantech.com/products/safety-products/eye-protection/TM2000-high-accuracy-gas-welding-lens.php

 

 

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Sounds good, but don't forget that it will not allow for fatigue, which is one of the expected fail points of a welded joint.

 

Somebody else mentioned glued joints. Not easy with aluminium, but I did one years ago and it knocked around for ages, never did give way, but I don't know where it is now.

 

I cleaned all the faying surfaces, then used a scotch brite pad, coated with epoxy glue, to give a final cleaning and spread glue to stop oxidisation.

 

 

 

The best common stuff I have found is "No More Nails", "Liquid Nails" whatever your local brand is, I actually checked a joint I did about 4 years ago the other day, amazingly solid.

 

 

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This is the reply that I received from a person who has a long time involvement with the construction of low MTOW aircraft.  I fully respect his opinion and am happy to admit that, while these brazing rods may be useful for joining aluminium where breakage of the joint is an inconvenience, breaking of a joint in an aircraft more than 6 feet above the ground is not an "inconvenience".

 

Hi Mark,

 

I had a look at your article.

 

Give me gussets and pop rivets any day!

The beauty of gussets and pop rivets is that it allows the frame to flex a lot (within the elastic limit of the gusset) without any fatigue.

 

The torch they are using will not heat the aluminium hot enough to weld it, it is more like brazing. It does make enough heat to

increase the oxidisation of the aluminium to which not much will stick! The low temperature filler will be way less structural than

the parent metal.

 

The way the filler was being used it looked to "encapsulate" the parent material, not really weld it.

 

I wouldn't use it on an aircraft part that may have my butt in at 5000 feet, thanks!

 

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Glad you took the trouble to find someone YOU trust and get the good oil.. Snake oil is maybe OK for snakes and the person selling it..  I for years welded aluminium with oxy acetylene where you have to use flux to stop the metal oxidising and quite a good weld can be made by that method but it has NEVER been approved for aircraft as poor technique will have flux inclusions which corrode from within . Metallurgy and stability of metal alloys comes into it also as well as reduction of strength at the weld section concentrating stresses in that part, and the necessity of post weld stress relieving. TIG (inert Gas shield) is a brilliant addition to welding technology, but it's another skillset and a need for the right equipment for the job..A steel tube fuselage frame could still be welded by a skilled welder using oxy acetylene and it doesn't need post weld stress relieving. A TIG often does but you will still distort the frame if you don't know what you are doing with any WELD  (or even braising) process.. Nev

 

 

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Glad you took the trouble to find someone YOU trust

 

That can be a problem with information obtained from the 'Net. The bloke who gave me his opinion is someone I know and whose work I have seen. I've never seen Facthunter's CV, so I don't know if he is full of knowledge, or full of sh.t, because I've never met him other than here. He has frequently posted sensible stuff on this site, so is he to be accepted as a person whose outpourings are to be accepted? Same goes for me. Very few of you have met me, but there are things that I post that are correct. I always try to back up anything of a serious nature with some research.  I don't see myself gaining kudos here if I post garbage in serious discussions.

 

Facthunter's comments on this topic have been sound, and hint at a lot of experience. I wanted to explore the product in an unbiased way, and had put some thought into the factors which can make the quality of a job using these rods poor. I'd still like to conduct the experiment, but if I accept the opinions of the bloke I trust, and Facthunter, doing the experiment would be a waste of time and resources. I have come to the conclusion that these rods could make a good joint if the person doing the job was meticulous, but how that joint would respond to the expected stresses in an airframe are beyond the ability of equipment I have to test the responses.

 

I still say that the rods would be good for making the fuselage of an RC plane.

 

 

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 I'm not inclined to state my background in detail as I consider the statements I make HAVE to stand up to scrutiny in their own right. I might be a bit straight to the point but people don't read long posts. Most of what I put here is not from a book it's usually my own (and often Hard) experience. I'm a very hands on person hard on myself and occasionally others when they behave like richard craniums. Not applying that to you OME but being around planes for a long time and working on Mechanical things that go fast there's not a lot of room for error. It's not my intention to spoon feed anyone or be the fount of all knowledge.  .Rather to inspire flying people to look a little harder than the seemingly obvious. and achieve a greater depth of understanding. The "never stop learning" applies to me as well as anyone. No on eever knows it all and when they think they do they stumble, usually. Balance the task with the skill level you have.  Be neither over or under confident.

 

 While I'm at it, what does concern me a little is when I post something quite  deep and profound,  (as I see it)  sometimes No one questions it or even" likes or says funny" it .It's the sort of thing everyone should have an opinion on. Maybe I don't express it well but let me know and I will give more info (or less if appropriate.) regardless of how big and complex or how simple and crude ALL planes fly by the same laws (of Physics) and principles, so it's all grist for the mill.   Nev

 

 

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OME  I watched a few videos on the rods that a couple of guys channels I am subscribed to on youtube. They seemed to have success with it....BUT as emergency first aid stuff... like out on a 4wd track and you bust something..you can use a gas bottle and these rods to effect a repair and get you home then deal with it later. The joints appear to be strong enough for sure but not maybe a permanent thing. They all stressed about having the SS brush and good cleaning first..then its basically like silver soldering where you must get the parent metal up to the temperature that will allow the rod to melt into the joint. So for a permanent build NO but as a get me home Barney job then maybe

 

 

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It makes it much more difficult to do a proper job later. Some very porous older aluminium castings are difficult to weld at any time as the porosity of the metal allows it to get corrosion sort of all through the article. Often It has carbon and oil in it also  so you get dirty welds, With TIG you can float a lot of this muck to the top of the weld puddle and sometimes the arc burns it away or you can flick the contamination  away with a steel rod. TIG is a concentrated heat source so you can get a big temp difference in a small distance causing a lot of stress in the metal. Nev

 

 

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Yes Nev but when your in the do do you dont care what happens after you then deal with it when you get back :)..the object is to at least get somewhere safely where something can be done...like those temporary rescue tapes...they get you to where you need to go to fix the issue

 

 

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