Welding Aircraft cowlings. Should I learn to TIG?

[cardiffrob]

Getting better at stacking but still unable to feed the rod through my fingers, so, every weld is a max of about 3 inches. My joining-2-panels has also been a bit shaky with lots of bits burnt back but I guess more practice is still needed. Getting better results with the foot pedal but my right hand struggles to hold the torch even without the need to depress that switch. I never anticipated this particular problem with my dodgy thumbs.

Ho hum.

 

[hotrodder]

There's several techniques for feeding wire, 3 vids here... http://www.youtube.com/watch?v=-Dll395Z5Qc, one i linked to has minimal thumb involvement. A TIG pen is a potential solution but expensive for what they are and might not be any easier to use due to the way they're designed to be held. Having said that i wouldn't worry too much about feeding wire, at least for now. Cut the filler wire in half and it'll be easier to use i.e. there'll be less 'bounce' due to the length so you can hold it further back allowing you to practice welding slightly longer distances

 

[NTwoO]

And practice while watching the footy

 

[cardiffrob]

Footie? Ughhhh. Rugby!

Anyway, I bought a small pack of 4043 /2.4mm rods (£20) and dropped by the laser cutting place where I cadged some sifal-27 pure ali rods in about 4mm along with some stainless rods in 1.6 after complimenting the boss on his 1943 jeep resto in the carpark.

Stainless rods did a nice job welding a lambda boss onto the Morris exhaust manifold and the 2.4 ali rods made a run of 8 inches possible in one hit without having to do any rod shuffling. I found that a steeper angle on the tungstens has also been a benefit, as has trying to get a finer finish to the tips. I need to buy a finer grinding wheel.

 

[NTwoO]

Whilst watching sex in the city, for all I care!

 

[500e]

Is alclad weld-able? have tried & asked others & been told No note cardifrob mentioned it

 

[hotrodder]

The alloys that are typically available as alclad are the high strength ones with poor corrosion resistance and weldability* like 2024 for example. Weldable flavours do exist as alclad (6061 for example) but any welds obviously won't be alclad...

* Many of the 'non-weldable' alloys can be physically welded but doing so will destroy their properties i.e. ends up softer and weaker than if a weldable grade were used

 

[chap]

RE. holding the torch.

Quite often the stuff we do is fidally little bits and holding the grip part of the torch doesn't feel quite right. A way that i hold it sometimes is to have the back part of the torch resting in the crest between thumb and finger (like holding a pen), use little fingers to curl round the grip a little. Sometimes hold even closer to the shroud, with the grip resting in the crest/along wrist.
Another thing the i do is sometimes wrap/drape the lead/hoses (water cooled torch) over my arm. This takes the weight off my wrist and makes manovering easier.

As for feeding filler rod, nothing wrong with my left hand and i've never got to grips with doing it! Most of the runs arn't that long, so i just pull more rod out between them.

Best of luck, and try some butt-welds if they are the sort that you'll be using on the cowlings.

 

[cardiffrob]

Been a while. Working on a 1932 Morris Minor (Think MG M-Type) and have been having a go at making toy versions of the front wings for the car. Thought I'd make a toy set in Ali first to work out how the heck to do it.

Question is, for cheapo 1050 ali how often should it be re-annealed?

Edit: Should also add that I'm on the prowl for a shrinker/stretcher and assorted othertools that could be used to make panels for this vintage car. Anyone???

 

[hotrodder]

Question is, for cheapo 1050 ali how often should it be re-annealed?

It's a tricky one to call but it kinda tells you when it's time... becomes less cooperative/progress slows right down etc. If there's still a fair bit of blocking out/roughing to do then it's time to think about annealing it again. If there's a lot of shape in that area it'll probably split if you try and carry on, especially with a mechanical shrinker/stretcher.

The side panel of this tank was spot annealed once...

The areas circled in red needed annealing, especially the bottom two, the green line was done simply to make life easier/faster. The yellow line was tweaked with a mechanical stretcher although pretty much all the material that got physically passed through the jaws got trimmed off. The area by the lower left red circle... the return where it meets the lower half of the tank ended up a tad under 1mm thick (began life as 1.5mm). That was done with mallets, hammers and slappers. A mechanical stretcher (at least a cheap one) would've split it- tried before with the Frost copy of a Lancaster, even with some emery cloth in the jaws so they leave stippling marks rather than ugly deep scores they still can't do it as well as the old fashion way. Something posher with more throat depth might but only if the jaws are the type that don't rip the surface to shreds

The other end of the same tank...

The bottom corners and the gentle radii got the same treatment as above. The rebate for the breather got annealed at least twice, probably three times. There's a LOT of stretching going on there and if i hadn't kept reannealing it it would've split

 

[cardiffrob]

That's Porn, that is.

I shrunk the edges with 2 x 5mm steel rods welded through the shaft of a steel tube to make a sort of 'pleating fork' (if that is what they are called) and then battered the tip down and flattened the rest of the pleat as per the video on Youtube. There seems to be quite a bit of wrinkling left even after lots of hammer and dolly work, albeit very shallow. Does this normally get filed down and polished out or must it be flattened? I was assuming that the shrunk areas are thickened and can withstand a few file passes.



I was just beginning to feel smug about having bent a piece of metal and then you go and show me THAT!




Off to Birmingham, Edinburgh, Glasgow, Salzburg and Gatwick. Back in 3 days.

 

[hotrodder]

I was just beginning to feel smug about having bent a piece of metal and then you go and show me THAT!

that wing section looks pretty damn even, when you've got two edges to shrink evenly by the same amount if the thing's not gonna end up twisted there's plenty to feel smug about, especially when it's a first/early attempt

The traditional way is to bump and file in that you give the area a few swipes with a file and then bump up the areas that the file doesn't cut i.e. combination of filing and planishing. Repeat until bored enough to reach for the DA. As you say the shrunk areas will be thicker* so can remove a few thou before you start to thin it (and stretched areas will obviously already be thinner anyway) and while it doesn't sound like much it can be enough to remove what looks like a right mess

Both these vids have been posted before so might have already seen 'em but this Kirkham Motorsports repair shows filing used with a 'bulleseye pick' part way through http://www.youtube.com/watch?v=9moYO-WWhaQ and a preview of David Gardiners bodywork restoration DVD shows the way he uses a file to metalfinish steel and ally... http://www.youtube.com/watch?v=IGElSHzm0q8

*it's taped together waiting for the owner to come and get it for a test fit but the side panel of a header tank i'm doing at the moment ended up pretty much bang on 0.5mm thicker in some spots. I'll take a pic tomorrow

Are you gonna wire the edges of the wing? That's where it can get really soul destroying. This vid kinda shows what's involved in doing it entirely by hand http://www.youtube.com/watch?v=hWVfXE3r3uk and this one shows a bead roller being used to tip the flange albeit in a simplified way as he's demoing on it on a flat panel (lots of tucks to deal with in real life when going around the curved front edge) http://www.youtube.com/watch?v=eOcZwr-1Y1E The Lazzed vid mentions 5/16 or 8mm margin, that's for 1/8" wire as the rule of thumb is 2.5D i.e. varies with wire dia

 

[cardiffrob]

Thanks for that. The videos have been most useful.

I've been given a nice old hand-cranked FJ Edwards jenny(?) like the one Lazze uses to get the first 45 degree pinch but no other rollers, not that I really would need them. Next question is "Why use steel wire for the wired edge?" Those wings for the Lagonda look so light that they ought to survive with either ali wire or even just a 180 dgree bend and then the wire removed. Am I missing something?

 

[KemppiFrog]

Thanks for that. The videos have been most useful.

I've been given a nice old hand-cranked FJ Edwards jenny(?) like the one Lazze uses to get the first 45 degree pinch but no other rollers, not that I really would need them. Next question is "Why use steel wire for the wired edge?" Those wings for the Lagonda look so light that they ought to survive with either ali wire or even just a 180 dgree bend and then the wire removed. Am I missing something?

The aluminium tends to crack from vibration if not supported by the wire.

I used to do a lot with DH 82a s and 86 s, but all rivited, so I am following this with interest.

 

[hotrodder]

While ally wire in an ally part is better from a corrosion POV, perversely being softer makes it harder* to use- it squashes and bends/moves around relatively easily when closing the panel around it which can easily result in a wavy edge. While ally wire is probably (?) better than a 'false wired edge' steel wire adds an amazing of amount of structure and stiffness reducing/damping vibration which, as said, reduces fatigue cracking. Stainless and ally ain't enitirely compatible and it costs more hence most people using plated/coated steel, often copper coated welding rods, for example... http://www.tinmantech.com/html/faq__dissimilar_metal_corrosio.php

For a false wired edge you can knock up a custom dolly to roll the edge most of the way and a second one to close it. Hard to describe but think short piece of rod welded to bit of bent plate (kinda like a tee dolly but with a cranked shank) for foming it most of the way and a second dolly with a concave face kinda like the negative version of tee dolly for closing it. Or you can miss the second step and just tip the return part way and close it 180* over the first dolly for a nicely radiused return

* admittedly a large part of it might've been down to it being my first attempt... years ago made a mudguard for a motorbike (not actually for anyones bike, just happened to be a front wheel laying around near the wheeling machine and i was bored/looking for practice). Came out of the wheel looking lovely, even nailed a reverse curve at the trailing edge and was feeling very smug. Decided to use ally wire to finish it off and proceeded to totally ruin it- tipped the edge nicely and got it most of the way over over while maintaining nice smooth lines, as soon as i started to close the edge it all went a bit 50 pence piece. Next attempt at wiring an edge i used steel wire and it went much easier

 

[PhillipM]

I've actually watched an old guy who used to do this for old motorcycle panels/mudguards, he used to brush the steel wire with some sort of rubber sealant stuff as he bent the ally over to seal it against corrosion.
Smelt like heldtite does but it was very thin, not sure what it was though!

 

[cardiffrob]

Piccy of the 'jenny' thing. Are the various forming tools still available? Can't find them for sale on the internet. Possible to self-fabricate? If so, are there any profile designs to copy or tips with regards to dimensions?

Makes it quite easy to fabricate joddles. (Morris Minor door bottoms)

[Off tonight to India for just one day stopover but will take me a week to make my way back. Only 34 degrees C warmer than the UK at the moment.]

 

[hotrodder]

There's a couple of examples of profiles in this thread... http://www.mig-welding.co.uk/forum/showthread.php?t=22886&highlight=bead+roller and googling 'bead roller dies' will throw out a bunch more (mixed up amongst jewellery stuff) for example... http://www.lazzemetalshaping.com/index.cfm/page/ptype=results/Category_ID=24/home_id=-1/mode=cat/cat24.htmand http://hoosierprofiles.com/Bead_Roller_Dies.html. Most, if not all of the sources selling 'em will be American probably

Typically just need access to a lathe to make 'em*, all of the Edwards machines i've used have located the dies using an offset pin i.e. no keyways to cut, just a hole to drill assuming the pin in the machines shafts hasn't been broken/gone awol over the years... They work fine with nothing more than friction from the nut holding them to the shaft anyway

As far as dimensions go the Hoosier profiles site hints at how to size 'em for the machine. In the case of rolling shapes into stuff like stiffening ribs etc then just need clearance for the sheet

*commercially made dies are typically a lot harder than mild steel and decent ones last several lifetimes. A bit of free machining mild steel will work fine unless they're for cutting/louvres etc and keep the cost down but will obviously be easier to damage and in the case of narrow/sharpish edged shapes like tipping dies will wear and not work properly once dinked

 

[cardiffrob]

Making a manifold for a sidevalve 1932 Morris. Started on Thursday night and have come along quite quickly.

Lots of grinding and polishing (it is all mild steel, not stainless) which is helped by using TIG on most areas. Still not 100% comfortable with my TIG skill so have done some tidy MIG in places where it doesn't need grinding back so much. Tiny bit of flange warpage so I'm hacked off about that. Had welded the pipes half way through the flange in the hope that the warpage would be zero. Didn't work out that way. Any suggestions for a good way of getting the flange flat again?

 

[cardiffrob]

Slight improvement over...

Originally rated at 8hp with a top speed of about 45 on an 850cc engine.