Welding Question......

[92GTS-R]

Thanks for the tips Guys.  Couldn't do anything today, far too damp   But I did get the car up on axle stands all around.

 

[Carolina_Mountain_Mustangs]

On my comment about phosphate. When cars are built at the factory part of the wash process is to on into Iron phosphate. It etches the surface and makes the paint stick better. You can do the same at home with hand spray on and rub with scotch brite or steel wool. What I am using right I got from POR but your paint supplier should know what you need. Follow their instructions makes the paint adhere much better. Here is a link to information on the material. Brand is not so important. When they dip strip a car they iron phosphate it and it can sit months and not rust. I have stripped panels in garage that have been there for years with no paint and no rust. Best to do the process and then epoxy prime. https://www.bonderite.com/en/technologies/pretreatment/iron-phosphating.html

 

[92GTS-R]

Update, well its taken me 3days to try and weld in a patch and its still not over   Its sort of a case of 1 step forward and2 steps back    

I tried to butt weld in the patch panel, it started off ok but grinding back the welds had been a tricky business, then when I shine a light under the patch panel I can see pin holes of light in various areas so have to try to add more weld, then grind back etc etc.

I did change the wire to the thinner wire.  Its getting there but [SIZE=16.1px]I'm[/SIZE] still not happy.   I will post up some pics.

 

[Fabrice]

It's not an easy job on itself and welding old metal with corrosion isn't helping. 

Often dismissed as a piece of cake, grinding right isn't that easy, especially when the sheets are not flush. Its very easy to weaken the metal and end up making a hole when you try to fix the tiny spot where the light shinned from!  Personnaly I usually grind only once the entire circle of welds is done and then do a 2 passes grinding. First using a thick disc hold as much as possible 45 degrees on top of the beads ( minimises to touch the surrounding metal and heat is little) and when its down to .5 mm, I use abrassive 80 disk after to finish and do not push as metal would turn blue in no time.

To minimise your 'light' issue, once all is in place and you fill the blancs between welds, start 2/3 on the previous point and pull or push the bath  3 to 5 mm away, this tend to remelt the first one and also give you a good start for heat without loading too much the sheets. Wire speed is important and doing so you should hear a high frequency buzzz. If not and bead looks ok but thick, reduce speed a tad. I know this took me a while and can't really describe in words but it's the sound the welder makes that you should listen. It really talks to you

Hope you'll be done soon, its really no weather to be outside atm!

 

[Bentworker]

I’d suggest getting some scrap sheetmetal and refining your technique.  I had to practice for hours and hours over a few days to get to the point where I felt comfortable welding on my car.

If your are seeing pinholes they could be from you not overlapping your welds enough. Weld porosity from welding where the air isn’t still, and having your shielding gas blown away may be another pinhole issue.  Last thing is weld porosity from dirty metal / paint.

Overlapping welds is a pain.  The correct amount of heat for thin sheetmetal isn’t enough to penetrate a previous big old cool bead.  This is why I grind my welds between passes.  I don’t grind them all the way down to the base metal, I just knock most of the bead off so that when I make my next round of tack welds the material Is a more consistent thickness.  This makes it easier to penetrate into the cool spot welds and not nuke a hole in the sheetmetal.

You’ll get it- just keep practicing.   Also it is normal to chase some pinholes- you are bound to make a few.  

 

[92GTS-R]

Well I've come in this evening after yet another day on the same piece ,it just got worse and worse and to say I'm upset is a massive understatement Yesterday I managed to slice into my finger with the angle grinder along the side of my nail and probably about 1/8th deep (that hurt).   

Remember I really did not want to do this Job in the first place but after being messed around for several months by so called welders i found via google, I had no choice due to a small retirement pension and could not shed out thousands of pounds to top American car restoration companies.

Sorry for the rant, just feeling down at the moment.

 

[Kilgon]

Hang in there.  I think we have all had those days where if it could go wrong it did.  I stick welded for years and when I switched over to a mig it was a new learning experience for me.  Same principal but the different was with stick welding I was feeding the rod instead of the gun feeding it.  Took awhile to get the speed and and temp settings right.   Takes time, practice and patience but it will come.  As everyone has mentioned above make small spot welds "tacks" only.  You barely strike an arc and no more or you will burn through.  May sound funny but I found out that striking an arc for the length of time it takes me to say "Mississippi" gets me a good tack.   Just make sure you move a little in circle (wiggle) from one panel to the other and back.  Hitting dead center in between the panels will burn through more easily than starting on a panel.    Also as for grinding let the grinder do the work.  Push into the work with only enough pressure to to grind the material.  Once close to being flush grind in short burst and keep checking your work.     

 

[Don C]

If your welder will handle flux core you might try it. It sometimes seem to work better on old rusty metal. If you try it you'll have to change polarity. If you are welding outside or using a fan to blow the fumes away you loose the shield from the gas, using flux core is a must, then.

 

[Fabrice]

Man, that's a nasty cut! But see the bright way, you have now made the bond, you have shared your blood with her steel! It can only go upwards from now on!! Oh well, at least that's how that goes in Avatar!

At this point I'd take a break, a beer (with the other hand) and go practice a bit more. This repair is hard, that's all. You'll get there, don't worry!  

 

[cwalker509]

Ouch on the finger.  I did something similar and started a thread on things like that (i have done something similar and other things as well).  I did lap welds for the most part.  Easier for me (also self taught). For a first try i think that panel looks pretty darn good!

 

[midlife]

Using a copper or brass backing plate beneath the joint helps quite a bit in controlling the weld from creating pinholes.  I agree: move side to side across the seam helps.  For floor pans and areas that are not visible and after tacking in place, you can lay a weld line (typically 2-3 inches) then stop and go elsewhere on the patch panel to minimize warping.

There are some days when you can do no wrong; then there are days when you can do no right in welding.  Ask me how I know...

 

[73MustangCoupe]

I totally agree with Midlife.  If I start burning through, I go to another area.  I'll come back and smooth out the backside a bit, and then use a piece of copper to back up the weld and then repair the hole.  Also, as Midlife said, since this is under the seat and the curves and beads nearby to take up any warpage that might occur, doing 1 inch beads and cooling won't bother anything.  Especially if you have a copper backing plate to help soak up some of the heat.  

It does take a lot of practice, so don't let the frustration get to you.  Just take a step back when you get frustrated, take a breather, maybe run some practice beads, and then take another go at it.  You'll get there.