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My mates one has  a bit more  as he has to wear correcting lenses and they (as you all know) tend to fog up so it has filter and  a fan. It was $1400 and he doesn't like to just spend money for the sake of it. I would like to be sure the speed the lens darkened was quick enough and reliable. Nev

 

 

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A basic device for protecting the welder must meet the Australian/New Zealand standard AS/NZS1338.1 - Eye Protection. This link lists other Standards  (https://www.awsi.com.au/blog/australian-nz-welding-helmet-standards) that should be met. Obviously, the more bells & whistles that go into a helmet will push up the price, and are of more use to a professional welder. As long as a DYI-er can get accomplished at striking an arc accurately at the weld site, even a hand-held shield can work.

 

The crux of the matter is the filtering ability of the lens.

 

 

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 Except you can't see anything till you strike the arc with the conventional goggles on or a shield. The self darkening feature is supposed to act instantly. I'm not sure how that can be guaranteed. OXY is not so much a problem. It's often the flux used that makes a lot of (yellow) light and a smoked lens would cope with that.. Nev

 

 

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Welding is the process of fusing of one or more parent metals either with or without a filler rod by heating the parent metal or metals to their elastic limit creating a liquid weld pool which is protected from oxididation and or rapid cooling by incorperating a covering flux or gas sheild during the process. It is not a heat addheasion or surfactant only additional metal such as soldering, brazing (unless brass parent metal is used) or silver soldering.  Their are no trick mirrors, its either welded or it is,nt.

 

 

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Can't see what elastic limit has to do with it. Young's Modulus covers elastic limit which relates to strain on a section of metal  Load/area and the elastic limit is reached when the metal stretches where it's deformed permanently. Nothing to do with melt.

 

 When welding, the Parent metal has melted to a  liquid state. Fluxes or inert gases are to prevent oxidation of the surfaces which would make the weld less strong.. Extra metal is added to the melt as required and the rod material is compatible with and mixes with the parent metal in the molten state..

 

  IF the parent metal is not melted, it's not a weld You can also butt weld with electricity or even friction. Sometimes the metals are dissimilar  as where valve heads Inconel are friction welded to the stems  You can also weld  low carbon steel with a forge and hammer using sand as a  flux. Nev

 

 

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The demonstration of aluminium brazing in the video posted by JG3 is quite impressive so long as you remember that the samples of aluminium he is using are probably very low strength alloys.  A few people have mentioned the reduction in strength in the heat effected zone of the metal being welded.  It's worth remembering that the reduction could be even more pronounced in aluminium alloys than in steel.  From Matweb, here are a few values of the yield strength of a few common aircraft materials in both their high and low strength forms:

 

6061-T0    49MPa     6061-T6    276MPa

 

2024-T0   76 MPa     2024-T3    310MPa

 

7075-T0   103MPa    7075-T6   462MPa

 

Any of these materials initially in their high strength form, if heated above about 200°C will eventually turn into the low strength form, and the higher the temperature the faster it will happen.  I think that of these materials, only 6061 is suitable for welding, but you can see from the figures you could be reducing the strength of 6061 by 80%.  The brazing rods in the video melted at about 700°F, or 370°C, easily high enough to reduce the strength of the material being brazed.

 

 

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Keep in mind this process is equivalent to soldering.

 

It is not suitable for load bearing structural construction, but is very handy for fabricating components that don't need to carry critical loads. No special equipment needed.

 

It's not all that difficult if you do the proper procedure: 

 

- Clean components and filler rod very well.

 

- Apply heat only to the components rather than the rod, don't get the rod in the flame at all.

 

- Rub the rod on the components and use the heat from the components to melt the rod.

 

- Very much like soldering.

 

 

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My Grandson has received a packet of those aluminium rods for Christmas.

 

Guess who is going to teach the art of burning holes in aluminium, will have to buy a new propane hose for myself, as the old I mean very old hose has sprung a leak.

 

spacesailor

 

 

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when i started my trade in 1963 first welding taught was gas welding , mig was,nt around yet,stick , sub arc fuse, so oxy/acet was used widely, i not seen it used in 30 years ,some brazing and silver soldering, to use oxy on airframes now is very old school, tig is widely used and some mig, i weld my chrome ally parts with ss arc rods, easy and very strong, some post heat used , look at most lsa aircraft from o/s and they tig most components very fine welding (my eyes not good enough for fine work) and very thin walled, rivets are a quick and easy way to assemble airframes thats the way i am useing on my airframe ,only welding is in noseweheel components,undercarraige and safety cage, for the homebuilt guys who dont weld rivets are the way to go

 

 

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Maybe you could make joints for the aluminium using 3d printed joiners.  Each time would be round and secured by a pop rivet.  Using Nylon infused with carbon the joints would be light and strong.  Each joiner would need post printing preparation using a reamer in each "hole".

 

A printer could make around 3 joiners per day, probably as fast as they could be used.

 

 

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Using a 3D printer to make items like these gussets sounds like a brilliant idea. Perfect repeatability; holes made by not printing in those areas; automated production. However 3D printing involves laying down a thin extrusion of material, then repeatedly going over the same path, laying fresh material on top of the preceding layer. This is similar to making pottery by coiling.

 

image.jpeg.735520256cb71c1ee80dbdb4816282b4.jpeg

 

 

 

The reason that his method is not suitable for making gussets is the poor strength of the bond between adjacent layers. The bond strength depends on the initial temperature of the exruded material, and its rate of cooling. Also the extruded material is like a tyre. It has only a small contact patch between layers. The bulk of the extruded material lies between.

 

image.jpeg.d5215bbaeb06e3d352b2ce97934c9bd0.jpeg

 

This reduces the shear strength between layers, which means that if strong forces are applied to the finished product, the bond between layers could fail and the component break apart. When making these gussets, it is important that the inter-component bonds act in all directions, not just along parallel planes.

 

 

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Hey the bond between layers is welding in a most controlled manner.  I have.made wheels amd forks etc.  Interlayer strength is ALWAYS tested.  You wouldn't believe the testing method, crude to say the least.  The layers are hit with a 10 pound hammer in a manner that puts shear stress on the bond.  However one must know how to print to get the best results.  I will send a picture soon.  I am so impressed with printed parts that the engine frame will be 3d printed.

 

 

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Just shows that unless you are riding the crest of the wave of a new technology, you fall off into the trough behind. I haven't played with 3D printing for about four years, and I didn't have one of those whizzo printers, just a simple Prusa.

 

 

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My printer seemed like a bargain.  Unfortunately it was the end of a design that was crap, a new design followed.  To print the more exotic materials I had to redesign significant parts of it.  It now has a water cooled high print temperature.  It took nearly 2 years of design, build and redesign over and over again to get to where it is. The effort is now paying off.  The advantage of 3d printing is that I do not have any need for welding.  Even the engine mount will probably be an exotic high temperature material

 

 

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Then PRINTING will be an over simplifying misnomer maybe?  although I don't know what a suitable replacement term for it would be. The thing about a rivetted lap the performance of it is well understood and is repeatable. Wood is a harder material to guarantee it's uniformity/predictability of strength and structural performance and so perhaps printed and composite structures. Even metallurgy has proven to be a difficult art at times in the Aviation world. The materials the Boeing SST based their design on Failed to produce the desired results at the time and the US SST was scrapped. the Original alloy in the Lockheed Electra/orion wings was  the cause of their premature grounding and wing replacement.. 

 

 

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The most accurate name for making objects by controlled layering of material is "additive manufacturing". Making objects by the controlled removal of material from an unshapped mass of parent material is "milling".

 

The use of the word "printing" arises from the analogy between how a dot-matrix or ink-jet printer creates a product. With additive manufacturing, the original "image" is repeatedly overlain with material as the machine follows the same path in the X-Y plane while rising in the Z plane after each pass. In milling, the machine lowers into the Z plane after every pass.

 

In both cases, the movement of the machine is through computer software which controls the movement in the X,Y and Z planes simultaneously.

 

 

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Two of my test pieces.  Glued together with 5minute epoxy, and clamped for 24 hours.  I couldn't separate them with a hammer.  I was surprised at the strength.  I will make the flaperons in nylon carbon and epoxy, 12 inch  a piece and glue them together.

 

I am in error in no welding in a previous statement, the exhaust will be welded.

 

15776587935587750017418175825534.thumb.jpg.41278389f0201d02b57bd07ac1a4264a.jpg

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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/

 

Provided that you design the aircraft in light of the (presently unknown) properties of the materials you are using you could use the methods that you propose.  The reason that that might be impractical is that this might require an increase in weight, may be more difficult to fabricate in practice and will have increased design and technical risks - no one else is doing it, so you get to be the one that finds out what goes wrong with the process.  This is often painful.  There does not appear to be useful engineering data on your proposed material, so you would have to test it yourself in order to do the engineering analysis.

 

The biggest problem is the change in properties you would get from heating the typical aerospace aluminium alloy, some of which respond very badly indeed, such as 2024 series.

 

Joints will of course require redesign to work with the properties of the completed bond, whatever that may be.

 

Using 6061-T6 as an example,  the temperature required for the “Ultra Bond” material would, at the least, reduce ultimate strength by close to a third.  You now have an unknown alloy forming your joint with unknown properties.  Naturally, you will need to test it to find out what those properties are.  Fatigue properties would be very important and would also take most resources.  And you need to find out if you can manage the quality of these bonds.  (How critical is the process control to the end result?) 6061-T6 can be welded using 4043, giving properties similar to 6061-T4.  With suitable heat treatment (of the entire welded structure), you should be able to get properties close to T6 again.  But at least there is data to support you on this endeavour.  Designing for T4 should achieve an acceptable result.  That might be practical for you to experiment with.

 

2024 series would be most impractical for the methods you propose.

 

For what it’s worth, some companies have found it practical to use electron beam welding to attach skins in stressed skin structures.

 

There has been a fair bit of research on the practicalities of welding aircraft structures with common aerospace alloys.  You could probably find some helpful papers in the NATO AGARD archive and from the US DTIC.

 

In terms of light aircraft, I suspect that the bolted web joint ends up being lightest, with few process control problems and few ‘unknowns’.  Fusion processes would seem very dependant on process control and would thus require an amount of development for each design that may be difficult to justify even for series production, let alone home builders.  

 

 

With regard to welded tubular 4130 structure versus aluminium alloy, the fatigue properties of the welded al. alloy joint could be expected to be ‘not real flash’, thus requiring much thicker material.  Forged or cast joiners with chemical bonds (eg, epoxy) would seem practical, but the burden of making the joiners would be high.  Using fabricated 4130 joiners with epoxy bonds to Al. alloy would appear practical - but it would be easier to make it all out of 4130, I fear.

 

 

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