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Bob uk
Unregistered guest
Posted From: 94.197.122.77
Posted on Saturday, 02 August, 2014 - 06:54 am:   Edit PostDelete PostView Post/Check IP

This skill not art and is not difficult.

Oxy acetylene is the most versatile by far.
Stick arc is lest useful in sheet stuff.
Metal inert gas mig is quick but limited
Tungsten inert gas is slower and more precise.
Spot welders are automatic and quick.

Hardest to learn is oxygen acetylene. Easiest is mig.

If you learn these two then using the makers handbook you will be able use the others.

I was taught oxygen acetylene and picked the rest up.

Go to arts and crafts to learn welding.

Top tips

When welding aluminum do not use aluminum filler rod because the filler rod will be a different colour usually lighter so use small bits of the material you are welding which why you can't see the join

To set.Oxygen acetylene equipment what ever the nozzle size is, a number, then the gas pressure is the same on both gauges, simples.
For car work 1 3 5 7 9. Nozzles. For.welding 18swg steel no 3 nozzle and see how it goes.
This shows the range of nozzles. Which last forever.

MIG is meant to have an inert shied gas. Co2 is not actually inert argon is. Most mig gases are argon and co2 for steel use at least 25% argon. If a hard weld is required then cheaper 100%co2. If steel is welded without argon the weld will be carbon loaded and harder and may try to stand proud during rubbing down and be harder to panel beat aluminum 70% plus argon I go 100%.

Apply above with panel beating and make a Shadow repair panel from a 5 worth of steel or an old bit of cortina roof.

(Message approved by david_gore)
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David Gore
Moderator
Username: david_gore

Post Number: 1418
Registered: 4-2003
Posted on Saturday, 02 August, 2014 - 09:43 am:   Edit PostDelete PostView Post/Check IP

Another function of electric welding gases is to provide arc stability and the gas mixtures are formulated accordingly.

I do not like Carbon Dioxide as a shielding gas because the arc breaks down the gas to Carbon and water vapour which can further dissociate into Hydrogen and Oxygen, Hydrogen and Oxygen have serious implications when welding ferrous materials due to possible hydrogen embrittlement [often evident as "fish eyes" in the weld bead] and/or increased scaling due to oxidation.
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Bob uk
Unregistered guest
Posted From: 94.197.122.85
Posted on Sunday, 03 August, 2014 - 07:33 am:   Edit PostDelete PostView Post/Check IP

Dave.
I thought that it was the carbon I use 100% argon and co2 with a mixer that way only 2 bottles.

I never get trouble and I have a free book from British Oxygen

Also I know good welders who will help

Like most engineering stuff the real deep stuff is there not to be learnt by rote but awareness that the subject goes deep and is backed by science is important because so many think it's a black art
Tip
MIG on co2 pops and splatters. Mig on argon sizzles like bacon.

(Message approved by david_gore)
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David Gore
Moderator
Username: david_gore

Post Number: 1420
Registered: 4-2003
Posted on Sunday, 03 August, 2014 - 08:42 am:   Edit PostDelete PostView Post/Check IP

Hi Bob,

The severity and implications of the Carbon and Hydrogen pick-up problems depend on the type of ferrous metal being welded, alloy content, tensile strength, post-fabrication forming/heat treatment and end-use requirements as applicable.

At the end of the day, welding is still very much an art and not a science just like forging [blacksmithing]. From personal experience, you can sense the metal "talking" to you as you work on it and the art is to recognise the implications of what you feel. There is nothing better than watching a true craftsperson at work IMHO.
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Bob uk
Unregistered guest
Posted From: 94.197.122.84
Posted on Monday, 04 August, 2014 - 05:21 am:   Edit PostDelete PostView Post/Check IP

The line between art and skill is fuzzy. And I find as you do things it appears to be an art which is hard then as you get the art things start to become logical and the it leans more to skill. The science behind the art and craft skill is important to know to a level and beware of the rest which is free on Wikipedia. Since Wikipedia has come out it hasn't made me more intelligent , but I know more such electronic stuff and music. When I first looked I was amazed at how deep subjects go. I know much much less than the total.
I watched a fitter heat a lorry chassis up and quench to repair a front to back twist of 2 inches.

It seemed like magic but the fitter explained that he knows by rough mental calculation how much the steel expands and heating the top edge forces the high corner doen and the quench shocks the steel and instead of returning to the original position the corner stay down a bit then repeat until the error is acceptable. So maybe more of a mix of experience art knowledge and skill, in various proportions.

I can weld well enough to repair cars to a professional standard and at that level it is very much a skill.

Maybe art craft skill are the same thing.

(Message approved by david_gore)
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Jan Forrest
Grand Master
Username: got_one

Post Number: 598
Registered: 1-2008
Posted on Friday, 08 August, 2014 - 09:10 pm:   Edit PostDelete PostView Post/Check IP

I've been teaching myself to MIG weld for while now with more than a little help from this forum. As said; stick welding is best suited to thicker materials than car bodies so my stick welder doesn't get much use these days. I used to have an electric brazing attachment for it, but I think I binned it long ago due to the high cost of the copper/carbon electrodes. Once I can convert it to output DC rather than AC I intend to retask it for TIG welding. I already have a scratch TIG torch and an Argoshield Lite cylinder with gauges (argon with 5% CO2 and 2% O2) as the shielding gas, although pure argon is usually better for TIG welding use.

Unfortunately my welds on thinner materials tend to be more agricultural than cosmetic, but I'm working hard on that aspect.

I've seen a video of someone using heat/cold quenching to 'pop' a dent out of a car boot lid without damaging the paintwork!. All he used was a small heat gun and a disposable cooling spray.
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 951
Registered: 6-2009
Posted on Saturday, 09 August, 2014 - 01:59 am:   Edit PostDelete PostView Post/Check IP

Jan,

If you know where that video is please post a link.

I have had several people tell me the tale of watching a paintless dent technician do exactly what you've mentioned here and how it appears to be almost magic.

Brian
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 451
Registered: 5-2012
Posted on Saturday, 09 August, 2014 - 02:11 pm:   Edit PostDelete PostView Post/Check IP

I can't help with Jan's video, but I found this "Father Ted" clip amusing:

https://www.youtube.com/watch?v=vcNiYQgsBUU
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Jan Forrest
Grand Master
Username: got_one

Post Number: 602
Registered: 1-2008
Posted on Saturday, 09 August, 2014 - 08:25 pm:   Edit PostDelete PostView Post/Check IP

If you pop over to You Tube and enter "removing a dent from a car" into the search box at the top of the screen you will be presented with several pages of options based on the term. Some are pure heat/cold reforming while others may involve tools which damage the paint/metal.

Enjoy!

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