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The moral of the story is that to join two pieces of metal together with by filling the gap between their edges with the same metal in molten form, first the areas that will be in contact with the molten metal have to be completely free of contaminants. For metals such as aluminium and iron, that initially means their oxides which will start forming as soon as the bare metal is exposed to the atmosphere. The heating associated with melting the rod and the surfaces can only accelerate the oxidisation. Now I understand why inert gases are blown onto the weld area to improve the job.

 

 

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We seem to have gone from building using welded joints instead of the usual, to repairing in the field.

 

I don't think I would want to use a field repair to get home if it was of dubious quality. OK maybe for a car or even a boat, but not for a plane.

 

I hadn't realised that Nev had a concern that we didn't tell him whether we found his posts good or not. I must admit that you seem to know what you are talking about Nev, I value your posts as I do for OME.

 

 

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If you desire to increase your welding knowledge and skills, you can't do much better than the Lincoln Electric website. Lincoln Electric have been around since welders were invented, and probably built some of the earliest arc welders.

 

Their articles are clearly-written, informative and straight to the point. Their welding and metals knowledge database is massive, and they hand that knowledge out freely.

 

Below, is a link to Lincoln's Aluminium GMAW welding advice - if you scroll to the bottom of the page, you'll find a heading, "View more aluminium welding how-to articles", which articles even provide information as to common mistakes in design, when choosing types of aluminium.

 

Maybe even our Chengdu-based UL-building guru will learn something from their information base, that will help him build a totally indestructible UL.  :cheezy grin:

 

https://www.lincolnelectric.com/en-us/support/welding-how-to/Pages/guide-aluminum-welding-detail.aspx

 

 

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Yenn I wasnt suggesting fixing a aircraft I was just relating what I saw and it was pertaining to the 4wd stuff. Actually many years ago I saw a doco about the Lincoln Electric factory and how they made their welders and how the workers were paid..they didnt work normal hours if they didnt want to,  each was on "piece work"..it was quite interesting ..especially for back then

 

 

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Sorry to tell you this, OME, but that welder you've pictured is obsolete technology, and I wouldn't even pay $88 for one. Inverter technology has superseded Transformer technology, and the advantages are;

 

1. Much lighter weight (7kgs as against about 40kgs). No more back-breaking work, lugging a welder into position.

 

2. Lower power draw (saves $$$'s).

 

3. A finer level of control over actual welding amperage (better welds in difficult conditions and materials).

 

4. A better and more stable arc, leading to a better weld quality.

 

I bought a Chinese (Rossi) 200A inverter welder off eBay about 5 or 6 years ago. One of these units (link below). I think I paid about $100 for it.

 

https://www.edisons.com.au/rossi-welder-inverter-arc-200amp-welding-machine-dc-igbt-stick-portable

 

I formerly owned a 140A CIG transformer welder, which provided good service from about 1985, until it died about 2013. The CIG welder was one of the first to have a PCB in it, and when the PCB fried, I found you could no longer buy it as a part.

 

So, I invested in the Rossi - making sure it used genuine Toshiba MOSFETS in its construction (the secret to reliability). I have done a lot of welding with that little Rossi, and it is, in a 2-word description, a "little pearler".

 

It has never failed to work, welds amazingly well, even on heavy thickness steel, and it works in dusty conditions, hot conditions, and generally cops a fair bit of abuse, and it has never faltered.

 

I would never go back to a transformer welder, they are like stepping back into a Sopwith Pup, after flying around in your Cessna.

 

 

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Look what I'm getting for Christmas

 

AWP-964-Hero-modified-lbox-600x600-ffffff.jpg

 

Usual price about $139. Christmas special price $88.90 at Bunnings. Limited stock

 

Usual price

 

Hi OME

 

I'll give you a better one than that for free; in fact give me a six pack of beer; that way we can have a beer to celebrate making a little more space in my shed.  I must ask would you seriously buy a mower from Bunnings (thay look nice but would not last long).  If you seriously looking at purchasing a welder at leat budget for another 2 1/2 times that amount and go to a better quality tool shop.  I do like the shield but I'm not sure if yo can leave it tilited up hands free.  Cheers and happy shopping.

 

 

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a few years ago in melbourne finishing a job and needed a welder in a hurry (had six in workshop back in brissie) i got one from bunnings ,absolute rubbish would overheat after a small run ie 50mm and would not run anything bigger than a 2mm. rod. long leads too short for doing high work and if you lengthened them would have dropped the amps down . inverter is the only way to go

 

 

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Sorry to tell you this, OME, but that welder you've pictured is obsolete technology,

 

It's not the technology that's obsolete, its the bloke posting the picture. This is the one Santa has on his sleigh for me:

 

image.thumb.png.d3daaafe23e646f9e9e33109aa95c6df.png

 

The new technology these inverter welders employ is amazing. I've seen videos of this type of Chinese overheat the operator before they overheat themselves.

 

 

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Ahhh, that's better, then. Haven't seen an Ozito inverter welder around, but the Ozito brand has actually garnered a few kudos for surprisingly satisfactory durability and reliability, for a cheap Chinese product.

 

The bottom line is, be aware of the duty cycle. I note the Ozito is only rated at 20% duty cycle @ 120A, the Rossi is rated 35% @ 200A, 60% @ 160A, and 100% @ 120A. Duty cycles are rated on 10 min time periods.

 

So, in practical terms, 20% duty cycle means you should only be full-time welding for 2 minutes, before giving it 8 mins rest time.

 

 

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Long ago I converted a Beaver ultralight to a twin-engine, 2 x 447's push-pull. 

 

I had fabricated an extra strong pilot cage, well integrated into the rest of the airframe and landing gear. Mostly MIG welded aluminium, welded steel engine support overhead forward. Some gusseted riveted connections in the tube and fabric airframe. The original Beaver construction was mostly bolted tubing.

 

Later, when extending a landing approach to avoid turbulence behind trees, caught the landing gear on a SWR line and tripped and hit the ground vertical nose down, REALLY HARD! 

 

That pilot cage and really good belts protected me really well so only got a broken ankle.

 

Later examination showed that almost every bolted joint broke out of the tubing.....

 

Some gusseted and riveted joints ripped loose but many survived even when distorted......

 

But not one of the many welded joints failed. NOT ONE, despite some being grossly mangled and distorted.....

 

Welding aluminium anneals the adjoining metal, so that metal becomes even more ductile, and bends and twists without fracturing, absorbing a lot of the energy. That was vividly demonstrated in this case, and saved my butt.....

 

So I have a lot of faith in welded aluminium, and have since built another ultralight with the airframe all MIG welded and an extremely strong pilot cage. Of course the wing with it's necessary flexing isn't welded, just standard ultralight ladder frame construction.

 

 

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Sorry to tell you this, OME, but that welder you've pictured is obsolete technology, and I wouldn't even pay $88 for one. Inverter technology has superseded Transformer technology, and the advantages are;

 

1. Much lighter weight (7kgs as against about 40kgs). No more back-breaking work, lugging a welder into position.

 

2. Lower power draw (saves $$$'s).

 

3. A finer level of control over actual welding amperage (better welds in difficult conditions and materials).

 

4. A better and more stable arc, leading to a better weld quality.

 

I bought a Chinese (Rossi) 200A inverter welder off eBay about 5 or 6 years ago. One of these units (link below). I think I paid about $100 for it.

 

https://www.edisons.com.au/rossi-welder-inverter-arc-200amp-welding-machine-dc-igbt-stick-portable

 

I formerly owned a 140A CIG transformer welder, which provided good service from about 1985, until it died about 2013. The CIG welder was one of the first to have a PCB in it, and when the PCB fried, I found you could no longer buy it as a part.

 

So, I invested in the Rossi - making sure it used genuine Toshiba MOSFETS in its construction (the secret to reliability). I have done a lot of welding with that little Rossi, and it is, in a 2-word description, a "little pearler".

 

It has never failed to work, welds amazingly well, even on heavy thickness steel, and it works in dusty conditions, hot conditions, and generally cops a fair bit of abuse, and it has never faltered.

 

I would never go back to a transformer welder, they are like stepping back into a Sopwith Pup, after flying around in your Cessna.

 

The first tig i bought was the CIG inverter type which just happens come with a lift tig kit. It is a bit harder to learn on, but my lame mate used it for a lot of the repairs on the bushbaby airframe which worked just fine. not overly expensive and light as onetrack stated. You can now "buy" smaller argon bottles with no lease payments each year and a good bobbin regulator is a great investment.

 

cheers

 

 

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Like most Chinese-made electronic stuff, the guts all tend to be the same. If that's correct, then I've seen a review of one of this type of DC welder and the guts were very well made with quality components. Those important components, like ICs  all bore internationally recognised  identifying marks so that the component's specs could be looked up on the 'Net or other electronics data base. The PCBs were well made themselves and the circuit components were well assembled. I don't think that this Ozito welder will be any different.

 

As for the quoted duty cycle, the figure quoted might only be a guaranteed minimum to cover the manufacturer's butt end. Some of these welders seem to be able to keep themselves within operating temperature for a long time. I would expect duty cycles to shorten as the OAT approaches 40C.

 

 

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For a inverter welder, that's a great price.

 

Amazing how cheap some really useful tools have become. But you can buy a handful of crap that is thrown out after Xmas. Full points for getting a useful present.

 

Grab yourself, a also cheap auto darkening helmet. Makes welding heaps easier and no problems of miss timing eye cover. On lookers can use the hand held one.

 

Buy some nice long blue leather gauntlets. 

 

Does the missus like to see you in leather? 

 

A leather apron or welding jacket is a hot but burn free look.

 

I have a ancient arc, mig and tig to use but a cheap inverter sounds great.

 

The small size and ability to do big work makes such a little beasty a nomination for best under $100 tool ever.

 

 

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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.

 

Murphy Renegade biplane was the one I know of.

 

I am a real lover of rivets and gussets for this very reason. Far easier, quicker and can be cheaper.

 

 

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Grab yourself, a also cheap auto darkening helmet. Makes welding heaps easier and no problems of miss timing eye cover. On lookers can use the hand held one.

 

Buy some nice long blue leather gauntlets. 

 

A leather apron or welding jacket is a hot but burn free look.

 

Nick orf! I'm a real He-man. Shorts, thongs and a nylon T-shirt. Look away when welding.

 

 

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The Argon is expensive whatever the unit you use. A Good self darkening mask is well over $1K and why would you consider a cheap one at all? What is your eyesight worth?

 

  Getting back to the original topic. The performance of riveted seams is well understood and a repeatable result can be achieved using that technique.. With wood and any welding, you get a wider spread of possibilities/performance variations . Welding on aircraft is used on high temperature ducting  jet engine burner cans etc but the guys doing that do a proficiency check half yearly . ON VH types exhaust systems and engine mounts Chrome moly. Some alloy fuel tanks are welded. .Nev

 

 

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If argon is so expensive, and relatively rare in the atmosphere, I was wondering why the most common gas, nitrogen, could not be used. A short dive into Wikipedia suggested why not:

 

When heated to decomposition or exposed to humidity, iron nitride may emit toxic fumes of ammonia. It is considered a moderate explosion hazard. Inhalation of iron nitride dust or powder may cause irritation to the respiratory system and possibly acute iron poisoning or pneumoconiosis.

 

Also, "Iron nitrides also make the strongest naturally magnetic material", just the thing for a vehicle that requires a compass as part of its operating equipment.

 

 

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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.

 

Well, they are probably glad they didn't bother. They were probably under the impression that chatting was okay... 

 

 

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 The "I" in TIG means INERT. Nitrogen is not inert. It's part of many compounds. I did read some of your stuff OME but it didn't appear to have much new (in principle) there. The Dillon Torch is a good gadget and is well made. Others have been patterned from it  but unless the parent metal and the filler rod are similar and melt at the same time it's NOT a weld. You can do some welds without a filler rod at all but you can't solder without applying a lower melt point added metal to the surfaces of both and ensure the faces in contact are "tinned"  or wetted by some of the Solder or Brazing metal. I did reply, admittedly not expressing much comfort to the idea of using these  techniques in aviation related work... . I don't think they even allow soft soldered fuel tanks anymore. They were the type used on the Tiger Moth. Nev

 

 

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A good quality auto darkening welding helmet can be got around $100. I have a reasonable $60 WIA one, which was great for most stuff, but wouldn’t reliably darken when TIG welding thin stainless at very low amps. So I bought a $120 one with four sensors instead of two and it works fine. Even the cheap ones have adjustable shades and sensitivity. 

 

 

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