A little advice please?

[icedaddyuk]

Guys,

Having a bit of trouble with overlap welding. I seem to be blowing holes in the top layer of metal without getting any/very litte penetration through the base layer.

I'm using a Clarke 135TE with argonshield mix gas (10l/min ish)
Wire speed 4ish on One Min setting (the lowest)

Using heretige car panels so around 1mm thick for each layer.

No pics yet, should get some later today though.


Thanks for any advice!

Adam

 

[ajlelectronics]

Well I am only a beginner myself, but my suggestion would be that the earth is not consistent over the two panels. Make sure the earth clamp is making good contact with both panels, via clean metal. The fact that you are blowing holes suggests that there is adequate current, but no earth to the lower panel causes no current to flow through it, leaving it unscathed.

 

[Chickenjohn]

I would advise taking a different approach for this work. Overlap welds are fine for bodging an old banger through the MOT for another year with crude overlapped patches that cover up the rust and get a pass but if you are going to the trouble and expense of using Heritage panels and this is a decent restoration on a classic car, then do a proper job- cut the panels accurately and butt weld them together.

If an overlap is part of the original design and the two panels were spot welded together at the factory, then punch 8mm holes through the top panel, clamp tightly to the bottom and plug weld the two panels together. Be sure to use weld through zinc primer on any overlaps and inside any box sections.

Really, overlaps are not the way to go when using decent quality replacement panels in a quality restoration.

 

[icedaddyuk]

I've tried butt welding panels together but lack of skill meant I was blowing holes in the panels and having to buy new ones, I can't afford to keep doing that. To be honest I'm happy with overlap welding (I'm only talking a couple of mm) welding the join from the top and the bottom as it gives me a little more breathing space when it comes to blowing holes.

Also, trying to clamp panels in position to butt weld is pretty difficult in a car as cramped as a mini!

Had more success today using the pulse method, starting to get the hang of it a little.

 

[malcolm]

Overlaps are a pain. The trick is to keep the top sheet in contact with the lower sheet so the heat from the weld transfers into the lower sheet preventing hole blowing.

Trouble is the top sheet will tend to lift off while you weld. To prevent that lots of tacks, short welds, and hammer the top sheet a little closer to the sheet you are trying to weld to between welds.

Starting the weld away from the overlap bit you are trying to weld in can help. If the top sheet is burning away starting the weld on the lower sheet and sending less time pointing the arc on that than the lower sheet might help bring it into the mix.

 

[Harry Worth]

Hi Icedaddy

Hi Icedaddy - sounds like you're going through what I'm going through at present. I've been trying to butt weld using the pulse method with some success. My problem is cutting the metal accurately enough that there are no gaps. I wear glasses which once I put on the goggles over the top to use my angle grinder always steam up. This plus my goggles seem to scratch very easily means I can't be so accurate. If the 1mm metal doesn't butt up perfectly, no gaps then I always seem to blow holes. I started using intergrips but they always provide a small gap which again meant blowing holes. The beauty of the overlap (joddle/joggle etc) is that it is very forgiving of fit and allows some adjustment. I've found it more forgiving on power of welder too. I've tried using some devices from LB restorations to hold panels together (see pic) - I haven't tried welding the section in the pics yet as I need to do some repairs behind. I'm still trying to work out how to weld a small flange on (thin metal onto a reinforcing plate that's 2mm thick). I'll probably have a go at trying to make a perfect fit panel that will butt fit in but if I fail I'll resort to the joddling/overlap technique. I'd be interested in pics of your lap welds. Cheers, Harry

 

[Robotstar5]

I wear glasses which once I put on the goggles over the top to use my angle grinder always steam up.

I also wear glasses and find a face shield better than goggles, stops bits hitting your face too!

 

[Harry Worth]

Cheers

Like the look of that - It might stop me looking like I've been working down a coal mine every time I've been in the garage. Dead give away when I try and persuade 'her indoors' I've been working down her 'things to do' list and not fiddling with my welder.

 

[SwissTony]

I'm still trying to work out how to weld a small flange on (thin metal onto a reinforcing plate that's 2mm thick). I'll probably have a go at trying to make a perfect fit panel that will butt fit in but if I fail I'll resort to the joddling/overlap technique. I'd be interested in pics of your lap welds. Cheers, Harry

Going by the tips page on the tutorials section of the main website, start the weld on the thicker metal, once the weld pool gets going, move across to the thinner stuff then immediately back to the thicker stuff.

I am a beginner to welding, so hopefully I have got that right

 

[Chickenjohn]

The best thing you can do is acquire the necessary skill to make neat butt welds- and you can do this by reading Malcolms excellent tutorials, getting lots of bits of clean 1mm steel and practising until you have the skill.

Overlaps are easier when you are learning the technique of welding but a bodge as a repair technique and if you don't have the skill to do butt welds then, sorry to say, but I think you need to hone the skills before starting work on a car. This is not just a matter of neatness, but of safety as those panels you will be welding in are part of the structure of the car and if the MOT man does not like what he sees he will fail the car.

Yes, I did a few overlaps on the first car I restored, but regretted each one as an overlap weld is a horrible water trap and there are signs of rust appearing in the overlap on this car ;-(. Butt welds are the way to go.

Look at Malcolms excellent thin metal pulse technique tutorials on this site for how to do butt welds. Once mastered, butt welds are far more satisfying and you can paint both sides of the repair. If you need an overlap then use the plug welding technique.

What you need to do before attempting to work on your car is get lots of 1mm steel pieces, perfect the overlap mig weld, then learn the butt weld techniques and plug welding. When you can do a consistent and good butt weld and plug weld then you are ready to start work on the car again.