Paul.
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What was the problem with the older mig welding George, and how did you manage to convince the tester that is ok?
- Thread starter GeorgeB
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What was the problem with the older mig welding George, and how did you manage to convince the tester that is ok?
I did remove all the scraps of outer sill which were attached to what I called the 'chassis rail'. It seemed like thicker metal. Was I still right, or could I have got away with 4 plug welds on the lower edge?
I run a bead along the vertical face of the lower edge. Then I ran another bead 'upside down' along the lower edge of the rail at full (modest) inverter power of 75 amps. It really blasted it but the surface was too undulating to leave an attractive bead pattern.
Good question. I'd added body filler to the edge of their overlay panel to blend it in. They'd previously (last year) blended it in as much as they could with an angle grinder. This year, the MOT tester said it looked like it had been repaired with fibreglass. Perhaps he tapped or put a magnet over my few mm of body filler. But what can you do? If you want to blend in an overlay panel, you have to slope it off with some filler, but then you risk problems at the MOT, it seems.
matt1978
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So there wasnt actually anything wrong with the standard of mig welding then, rather more a case of the poor way they had finished it off?
I got the impression from your earlier post that they wasnt happy with the quality of weld and you would of expected better results from Mig.
Yes, it was a bit unfair of me to make out it was MIG's fault. I just found it amusing that the MIG repair failed and the ARC repair passed MOT standards, at the highest, simplest, most misleading level of summary. I don't apologise though, given the amount of unfair scorn and ridicule poured on Chinese junk like my DC inverter and absolute rubbish like my AC buzz box, both of which I personally find to be absolute gems.
As it happens though, I did think the MIG welding looked a bit 'weak'. I'll try and dig out a photo from last year.
matt1978
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A bit unfair?? I would say totally mis-leading.........
The mig repair only failed because of how it was finished off, nothing to do with the weld or the welding machine..........although the finishing must of been truely shocking if they let yours pass and failed the other one.
The mig repair only failed because of how it was finished off, nothing to do with the weld or the welding machine..........although the finishing must of been truely shocking if they let yours pass and failed the other one.
matt1978
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Yes, some of the welding carried out at these garages, is not the best to say the least......wouldnt make any difference weather it was Mig or MMA, some of the so called, repairers I have seen have been worse than useless at welding!
gavuk
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......it was George's filling not the mig weld.......
malcolm
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We had a look at the MIG weld during the arc welding meet. It was poor - done by a garage monkey that couldn't be bothered in my view. The arc weld looks poor too, and I know how much effort has gone into that.
As a result George has concluded no process is capable of laying anything other than bird poo. But because the arc welder cost £5 from Aldi it is better. He's just winding you up Matt - ignore him.
As a result George has concluded no process is capable of laying anything other than bird poo. But because the arc welder cost £5 from Aldi it is better. He's just winding you up Matt - ignore him.
The finish of the professional MIG weld was a lot smoother than my DIY arc weld but I bet it wouldn't prove as strong if put through a stress test. The smoother profile was because the garage made far greater use of a grinder than I felt the need for. I could grind those arc welds almost flat if I wanted to, but what's the point? The lower sill is almost hidden.
I've done no such thing as conclude that nobody could do better than I did. Of course not. But it passed and that was my main objective for this first attempt. Neither of my arc welders came from Aldi and none of them cost as little as £5. Far from winding-up Matt, I was simply being honest.
Come on George, that must have made you chuckle over your cocoa!How about winding this thread down, it's pretty much run it's course now, surely?
When they told me that some welding had failed, I naturally assumed it was my welding which had failed. Yes, I chuckled when they pointed out that the garage's MIG welding side had failed and my arc welding was how it should be done. Well, yes, it was really my filler finish which they didn't like but 'MIG failure' makes a better story. OK, I won't dig out a photo of last year's MIG weld if you think the thread has "pretty much run it's course now."
Here were two photos from last year - now deleted due to much apparent interest. It's a bit risky posting photos of other folks' work, especially if few people express any interest.
The car failed the MOT last year because of rust holes in the nearside rear sill. The garage used a MIG welder to apply a plate over the rusted area. They then painted it with mastic and the same garage got it through the MOT. When I got the car home, I used turps to remove all the mastic, and I took some photos. On the one hand I was impressed with quite a neat job - a lot neater than my arc welding this year. But there were a few holes in the welding or perhaps over zealous use of the grinder. Is this professional welding really up to MOT standards?
The car failed the MOT last year because of rust holes in the nearside rear sill. The garage used a MIG welder to apply a plate over the rusted area. They then painted it with mastic and the same garage got it through the MOT. When I got the car home, I used turps to remove all the mastic, and I took some photos. On the one hand I was impressed with quite a neat job - a lot neater than my arc welding this year. But there were a few holes in the welding or perhaps over zealous use of the grinder. Is this professional welding really up to MOT standards?
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I think that's pretty shoddy work for a garage that's supposed to be a professional with these things. I had some welding done at a garage once. I don't have the pictures unfortunately, but it was perfect. They just did the welding and put some primer over it. I couldn't even tell where the seam was. Just looked like all one panel.
To be fair, I did agree to the low cost approach of an overlay patch so it would never be as neat as a butt-joined repair. On the first photo, I guess we can see tacks of MIG weld. The problem there, I would have thought, is the holes and the MIG weld only looks semi-continuous.
As for the lower edge join in the second photo, I really can't figure out what they did there, it's so well blended in. But I'm sure their lower edge joint is not as strong as my arc welding.
As for the lower edge join in the second photo, I really can't figure out what they did there, it's so well blended in. But I'm sure their lower edge joint is not as strong as my arc welding.
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That MIG welded section looks bad - it seems as it did not penetrate and fuse with underlying metal too well. Bad settings, machine or inexpirience? Anyway, no matter how you look at it, it's not good.
On the other hand, stick welded repair looks strong, although I could not say it looks too good. Maybe a fair bit more grinding would make it look better, but then question of joint strength remains. It think a proper MIG in good hands could do miracles patching that up.
On the other hand, stick welded repair looks strong, although I could not say it looks too good. Maybe a fair bit more grinding would make it look better, but then question of joint strength remains. It think a proper MIG in good hands could do miracles patching that up.
wallopadonkey
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george i believe that 1/2 an inch of properly penetrated mig weld will hold 1/2 tonne in weight so the break test in all circumstances is pointless as the parent metal will fail before the weld does!
It wouod look better if your weld had been ground back and would have got rid of any areas to hold water thus promoting rust did youfill your arc weld with seam sealer to finish it.
dont forget george the large blobs of weld above the surface will not aid the strength so can be safely ground off.
It wouod look better if your weld had been ground back and would have got rid of any areas to hold water thus promoting rust did youfill your arc weld with seam sealer to finish it.
dont forget george the large blobs of weld above the surface will not aid the strength so can be safely ground off.
I'm sure you're right. 0.8mm steel sheet isn't all that strong in the first place and by the time rust has eaten it back a bit, it's probably down to as little as 0.6mm - and that's the 'solid' metal.
Now I have the MOT certificate, I may grind it back just to see how it goes. I asked about seam sealer in a shop today and they are awaiting a delivery of 'dum dum' if that's what it's called. Is that the stuff? Can that be used to fill surface low points in a weld? Wouldn't body filler be better?
I thought the large blobs of weld metal above the surface might increase the strength of the joint a bit, but perhaps not.
