Welding advice needed: bulkhead repair to new inner wing

[Tail]

I frequent these Mig welding forums http://www.mig-welding.co.uk/mig.htm and the tutorial section is quite good if your not sure and there are also power and wire feed calculators, as all machines are different so unless someone is using the same machine as you the settings are trial and error until you get a consistent weld with good penetration, there are also some good techniques on this site for welding thin steel without burning through all the time. Good luck

[940_Turbo]

Originally Posted by 1966 122s

Thanks again,

The BFH is one of my favoured tools !

When a asked about whether to put the repair panel under the hinge... I mean the new repair section which I plan to make out of sheet steel to repair the missing edge of the bulkhead. i.e. Would the experienced out there unbolt the bonnet hinge from the bulkhead and make a repair which goes under te hinge plate or just weld the repair sheet to the bulkhead near to the hinge plate ?

The experienced would slice off the rusty metal make a repair section and seam weld it in invisibly edge to edge. However without a bit of practice you're likely to end up with distortion on the first few attempts. If you weld with big overlaps, or over the top of the rust, moisture will creep in and it'll rot out again.

The trick is to weld in short lengths. Shifting from place to place without allowing too much heat buildup in the panel. The other good thing to have is a brass block as a heat soak. Hold it behind the weld seam. Because it is brass the weld won't stick to it. Do wear welding gauntlets.

As to the settings it depends on the welder. You need to achieve hood penetration and minimise build up of the weld fillet. Listen to the sound, it should sound like sizzling bacon.

[Burdekin]

Agree with 940, never patch over as it just hides the problem. Another good tip is to make or have the repair section on hand before you cut out the rusty section. Don't do a half job when removing rust, while you're there why not just remove it. I'm not sure what you mean about the hinge but removing the hinge is a good idea as that will give you more room to weld around and then grind the welds. This also goes for removing the wing, why make it harder for yourself to weld properly. The wing comes off easily and you get the chance to check all is good under the wing and put new nuts and bolts on. Make it as easy as you can when learning!! Don't use less than 1mm thick metal, the thinner it is the harder to weld, takes longer to weld as you can't put as much heat in at one time and the more it will distort on larger sections. I always match the surface height by feel which I find is the most accurate, so I normally clamp on end and hold the other in place at the right height and tack it in position. Tack the repair section in place and when learning grind most of the tack down before you weld over it proper so the weld will be nicer then. You will get less distortion on flat sections if you weld in small lengths (1cm say) and in different spots, so weld one end, then the other, then the middle etc. You will also get less distortion if you transfer the same amount of heat into both sections of the metal so weld in line with the joint with a mig if you can on flat sections.

Surface prep is critical to getting a nice weld especially when you are beginning. If the weld is poor grind it off and start again, don't try and weld over to make it look good as you will only make it worse. I use flap wheels in my grinder to prep the surface and grind welds. These work much better than grinding discs. Even grind the new metal as it can have oil on it etc. Butt the two joining surfaces together for welding, you don't need a gap as a gap only makes it harder when learning. You only need to bevel the edges and you will get 100% penetration if you have your amps and wire speed set correctly and it will look better on the rear side than if you had left a gap.

And the number one tip, always keep your eyes open and watch the weld. ;-)

[Burdekin]

Originally Posted by 1966 122s

Thanks again,

The BFH is one of my favoured tools !

When a asked about whether to put the repair panel under the hinge... I mean the new repair section which I plan to make out of sheet steel to repair the missing edge of the bulkhead. i.e. Would the experienced out there unbolt the bonnet hinge from the bulkhead and make a repair which goes under te hinge plate or just weld the repair sheet to the bulkhead near to the hinge plate ?

If under the hinge is good metal no need to cut it out, leave it and make a repair section around it.

[Burdekin]

A couple of other wee tips. If you blow a hole, two ways I fill them is short quick little welds around the edge of the hole working in to the centre but keeping the weld molten or let out a length of wire (say 1 to 2") and then start the weld and push it into the hole quickly. You will get the hang of it. Don't be worried about blowing holes, if you don't you most likely aren't getting good penetration and have your amps and wire speed too low.

Second tip is if you can, brace yourself or your welding hand to keep it steady. And have the welding lead supported, like over your shoulder or resting on what your welding so you're not trying to hold it up while your welding.

Third tip, keep the earth as close to the weld as possible. The electric current runs from the earth to the electrode. So if it is close it passes straight to the weld only. If you have it far away it goes through whatever it needs to to close the loop. The current can arc across bearings which will cause them to fail after a while or cause electrical problems.