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welding critique...
https://www.ausmini.com/forums/viewtopic.php?f=2&t=26557		 Page 1 of 1
Author:  simon k [ Mon Jan 08, 2007 10:07 pm ]
Post subject:  welding critique...
hiya welding experts, I was lucky enough to be given a 200A unimig for my birthday in December, so I have embarked on fixing the rust in my cooper, which will involve replacing some panels, including maybe a total of 1m seam, and lots of spot welds...

I've used ARC and Gasless MIG to a reasonable extent, (I'd rate myself 6 out of 10), and today I got a bottle of gas (supagas argon 07 - can't remember the percentages) to try out with the 0.6mm wire I bought before Christmas

so heres my first attempt, butt-welding a bit of scrap body panel from my van. At first I had the wire too slow and the weld was running up the wire making little balls with no penetration, so with the wire speed up, the voltage at its lowest setting, the amps were reading about 35 (I think - maybe lower). The gas is at a little over 10l per minute

any comments? how will this go with bodywork, spots etc.?

this is an extreme close-up, the actual weld is about 20mm long

Image
Author:  willy [ Mon Jan 08, 2007 10:16 pm ]
Post subject: 
I'm no expert but that looks like perfect penetration 8)
Author:  drmini in aust [ Mon Jan 08, 2007 10:19 pm ]
Post subject: 
Looks OK to me. :D
That gas is probably like Linde Gas' Corgon 07, ie 7% O2 in Argon.
Welds nice with little spatter, but it's designed for CLEAN steel.
Also it's not that flash on positional work as the weld pool is very fluid.

I recommend a mix with 5%CO2 and 2%O2, it's better on thin sheet with rust or poor fitup.
BOC Argoshield Light (was Argoshield 50),
Linde Corgon 5/2,
or Air Liquide Blueshield 23.
Author:  mini-dunger [ Mon Jan 08, 2007 11:29 pm ]
Post subject:  weld
You know its a good weld :D

100% penetration and it looks like there isnt any porosity. Butt welds are one of the harder welds but thats good. You were probly going a bit too slow but you didnt blow a hole so its fine. Even the best welds on old steel look pretty crappy.

My preference is to have the mig set up quite hot. Its easier to blow holes but penetration is better and I find it flows out a little more and is a little neater. I have only a little formal training but I work with guys that are "professionals" and man they are some average welders. Welding is an art form kinda like painting, being a "welder" and being a "good welder" are very different things. You will know your welding properly because it just feels right.

end rant
Author:  Angusdog [ Tue Jan 09, 2007 5:51 am ]
Post subject: 
Looks all right to me. And a good idea to get plenty of practice and work out all the heat settings, especially on really thin steel, as when you're putting a patch in due to rust, the surrounding steel is very thin.

I'd advise buying a sheet of 0.8mm steel, and get the supplier to cut it into four bits so you can carry it and store it. It's cheap (about NZ$60) from memory, means you have more than enough clean, straight steel for all your mini-patching needs. Plus it takes up no space in your garage as it's so thin.
Author:  drmini in aust [ Tue Jan 09, 2007 6:05 am ]
Post subject: 
Don't be tempted to use galvabond or zincalume sheet, it's a bastard to weld. The zinc will fume and make the arc fierce.
If you MUST weld zinc coated, grind the zinc off the weld area first. :wink:
Author:  graham in aus [ Tue Jan 09, 2007 8:13 am ]
Post subject: 
Hmmmn very nice Simon,

Now, when are you coming round to see me................

I have a couple of little jobs for you!!!!!

:shock: :shock: Lol
Author:  9YaTaH [ Tue Jan 09, 2007 10:42 am ]
Post subject:  From the QC Dept for Simon
G’day Mick

Looks OK for panel welding to me. Not done much of it myself. If that’s penetration then it looks great as there will be good reinforcement when the shiny side is ground off. You can get a flap disc to suit a 4 or 5“ grinder at various grades of roughness so a quick sand of the weld area will reduce the discolouration that is noticeable.

The only other thing is that 15-18 litres per min is more the norm for GMAW (bare wire MIG).

I still however don’t recommend the welding of chassis or towbars etc by the untrained. A good test of any welding is to do an inch or so in a right angled fillet and break it back towards the weld. This will show fusion to the parent metal to prove it’s hanging on.

Your friend has penetration in a butt weld which also proves fusion for that joint configuration. Be keen to know the grade and brand of wire he brought.

Best welding picture you have ever sent me. I’m a bit more confident with this one.
UNQUOTE
Author:  mini-dunger [ Tue Jan 09, 2007 11:16 am ]
Post subject:  ZInc rtch primer
There is this product on the market called Zinc rich primer you can buy in a can. Its is marketed as a product you can spray over metal and weld through it. Being the thorough person I am I sprayed it all over the place. I then found out this crap isnt as weld through as I thought.(it was worse than galv) Keep it all bare and clean then worry about rust prevention afterwards.
Author:  simon k [ Sun Jan 14, 2007 5:29 pm ]
Post subject:  Re: ZInc rtch primer
mini-dunger wrote:
There is this product on the market called Zinc rich primer you can buy in a can. Its is marketed as a product you can spray over metal and weld through it. Being the thorough person I am I sprayed it all over the place. I then found out this crap isnt as weld through as I thought.(it was worse than galv) Keep it all bare and clean then worry about rust prevention afterwards.


I've wondered about that - I have been drilling a lot of spot welds from the car, and I am finding rust between the seams, I was planning on putting something between them before I weld, and I was thinking that weld through primer would be the stuff.... but :?

like my spot welds?

Image
Author:  Mini Mike [ Sun Jan 14, 2007 7:09 pm ]
Post subject: 
Yeah the weld through primer is good mate.. Its designed for spot welds not realy ,meant to be for big runs... You will be alright if you are going to do plug welds..

Just remember though you dont do big runs when welding cars, You will get massive distortion an end up with a much bigger job... You can do small stiches about 10mm and move over the other side... It takes longer to weld but there shouldnt be much distortion.. If you touch the panle after welding with you hand and it more then warm.. Its to hot. And dont cool the panel with water, you will shrink it and get sistortion aswell.
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