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Discussion Starter · #1 ·
Just crossing my mind, but when I need to weld in the sheet faces/ends to the arches on the Austin, the new metal will be at a right angle to the arch metal. Now, is it better to weld on the inside or the outside of the joint i.e the acute angle or the obtuse, inside or outside the arch? Does this make any sense? :confused:
 

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Discussion Starter · #5 ·
don't follow ?

what are you welding ? and where is it seen ?
At the moment they are like this (although this is an old picture, the arches haven't changed much):



......but the 'ends' were cut off them because the arches are effectively getting narrowed......



..........so I am going to have to make a new pair of those above, only flatter, just a simple face of sheet metal on each arch. So what I am asking is, do I weld inside the arch when I make these new ones and attach them to the existing arch structure, or along on the outside edge?
 

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Nowheresville
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TIG or gas welding would be far easier on the outside of the joint - just make sure you get sufficient penetration that when you dress the welds they're still joined together!

MIG could be done either way, but to avoid welding upside down (unless you can turn the body over), on the outside of the joint would be OK, again ensuring good penetration. I think if I was doing it with a MIG and had a way of turning the body I would weld on the inside of the joint: this would allow for a larger radius to be ground on the top side, and might look nicer.
 

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Legs and heels subscriber
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Weld from outside with MIG and stagger the areas you re working on to minimise heat transferring up the panel.
ensure all metal surfaces are spotless clean and then dress.

would avoid tig / gas welding...too much distortion on something so thin.

Alternative would be brazing and then hand file to nice finish if the repair section fit is good.

Stuart
 

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so from what i see is that if you weld on the out side of the car (
inside of the wheel arch) you would have a fillet weld to do.
but if you weld the on the inside of the car (around the outside of the wheel arch.) you would just have a corner joint.

close tack the joint corner to corner around the outside of the arch and using mig or tig then weld from the outside (corner to corner) this should penetrate trough enough to leave a bead of weld on the inside of the wheel arch.
if tig welding destress the weld by hammering around the weld lightly.
 

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I would make an mdf hammerform the shape of the "tub". Put a flange all the way around it and then you can put holes in the arch and rosette weld through them.
 

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The key to welding the outer of the arch (known as an open corner weld) is to dissipate the heat around the entire weld. tack the panel in place and then Use tack size welds only (in between the existing tacks and alternate them so each weld is cool before you perform a tack next to it (slow but the distortion is drastically reduced using this technique) you should then find you are tacking into smaller and smaller spaces between previous tacks, until you are finishing off the seam (this technique is known as back welding) once the welding is finished you can then hammer the weld (not too hard to prevent damage to the panel) this will then "peen" the weld and relieve a good deal of residual stress. you can then finish off and grind the seam. set the mig so that the penetration will leave you with a small internal fillet weld.
a fillet weld (inner arch weld) will always distort more than an open corner weld (outer arch) if you are using tig, place the wire onto weld site and fuse the wire onto the joint (as opposed to feeding the wire into the molten pool) this will reduce heat input.
 
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