mig gas welding problem

helpimcrap

helpimcrap

helpimcrap

Soldato
Joined
13 Jan 2004
Posts
12,778
Location
Leicestershire
a lot of you work on your own cars so figured this is the most useful place .

a mate is welding an arch onto a sierra and he keeps blowing holes in metal. He can weld ok as he's put a sill on same car, same day just fine.

what can he do though as hes at a loss.
thoughts are:

the gap is too large - about 2mm in places but touching largely.

in order to sort the about put metal behind it so there's no gap but it still keeps blowing holes in the metal.
tried turning it from high to medium but it still does it.

seems that the metal seems too thin to weld o or temp is too high but tried changing those issues and nothing.

thoughts?
 
i find it hard to explain but if the join is horizontal the weld puddle needs to start say 3-4mm on the top panel and then bridge the gap and go to 3-4mm on the bottom panel. it should then be like doing a squashed sideways S moving the weld puddle up and down all the way along. you must not just weld in the gap, it will burn the edges and blow holes ;)
if that doesnt work turn the power down more and maybe increase wire speed and weld faster.

practice on scrap metal first ?
 
Sounds like he's using too thicker gauge rods/wire. So the amps are too high and it's blowing through,

Can you get thinner rods/wire?? then you can wind the ampage down.. :)
 
Has he not gone back to clean metal? Is he blowing holes in the patch or just the arch, sometimes it's rusting from the back and you don't realise you are trying to weld to what is essentially rust.

Any idea what thickness wire he's using? My welder came with 0.8mm IIRC, switched to 0.6 and I'm getting some lovely welds now.
 
he had it sorted and very respectable too apart from warping the rear quarter coz it got too hot so will need to skim it with filler but a good job done.
 
You need to be using 0.6 or 0.8mm mig wire.
Start the weld pool on the main panel- in this case the quarter, then melt and feed the wire into the weld pool taking the edge of the new arch panel.
The key is to only weld about and inch or so at a time then work on the other end of the panel, doing one continuous weld causes the panel to warp, alternating welding areas allows it to cool stopping the warpage.
There shouldn't be gaps between the new and old panels, spend more time fitting before welding, if you really need to "fill" then short sharp welds built up can fill up holes/gaps.

Gas is good, but creates even more heat and more warpage.
MIG is the easiest of all to learn.
 
You must log in or register to reply here.
Back
Top Bottom