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Welding critique please...

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Been practicing welding vertical lap joint, 3mm new stuff to ?mm chassis.

After a few pigeon poo runs i managed this. I think it's ok but please, advice and guidance is welcomed.

The image is correctly orientated ie the chassis section was stood on end.

Upside-down next... <shudder>

 

20180507_200802.jpg

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I am no expert at all, so don't expect too much of what I say to be factual :D But I'd say the poor welds on the otherside is mostly down to rust/dirt messing up the weld. Looks like there has been no shielding gas, and that is usually contamination. Welding on an old chassis, especially in the corners is often like that..

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Only the vertical one please - the rest are me learning and I know they are sheyte

:D:D

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That looks fine , as Soren says to get a good weld on an old chassis you need to clean the area were your welding of all the rust and carp or you will get porosity in the weld . I've always found when welding vertical and from underneath it helps if you turn the wire speed down slightly to what you would have it when doing a normal weld . Also try and cut out the rotten area and weld a piece of new in , on an old chassis you can also cut some 5mm strips out of the plate your using then tack them to the inside of your hole then fit your new plate to the strips , makes getting a good strong weld much easier . And when welding underneath make sure your not lying directly under were your welding , lie to the side I've got some lovely burns over the years from work were a lump of weld has dropped off and when it goes through your clothes and onto skin you never seem to be able to get to it to get it off .

cheers Ian

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Are you MIG welding vertical down?  If so, you tend to get a lot of cold lap with that technique unless you really know what you are doing.  Unfortunately, what you see on the surface is not indicative of the weld quality.

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2 minutes ago, Red90 said:

Are you MIG welding vertical down?  If so, you tend to get a lot of cold lap with that technique unless you really know what you are doing.  Unfortunately, what you see on the surface is not indicative of the weld quality.

Yes, vertical down... should I be going up?

This is what the other side looks like: is that 'penetration'?

 

20180507_213612.jpg

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Note the tapering off of the penetration heat zone , the further you go in one run the more likelihood of cold lap as red90 says . Chopping a few practice pieces across the weld and bending the sample along the weld will help to show you what you are getting . It looks like you are getting close to it .

cheers

Steve b  

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Up is a safer weld.  When you go down, it is easy for the puddle to get under the arc unless you are very good and observant.  Most codes do not allow vertical down, because of the issue.  The picture is just heat discolouration.  Full penetration would show melted steel.

Also, if using MIG, you need to clean the area very well (grind to clean steel).  Since there is no flux in that type of welding to remove contaminants, they get dissolved and entrained within the weld.  If you need to weld dirty things, stick or flux core is a better choice.  It is easy to make MIG welds look good, but very hard to make them strong.

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Thanks for the comments gentlemen - I'll have another go tomorrow night :)

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This guy's welding channel is the best you will find.  

 

 

Edited by Red90

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Covering downhill.  He shows here how easy it is to make a nice looking downhill weld that is lacking in fusion.

 

Edited by Red90

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All I would add to the existing comments is the starting surface didn't look very clean - abrasive flap wheels are your friends. It needs to be SHINY before you start, I generally aim for at least a 1" wide shiny area all along the path to be welded.

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Yup, people say it needs to clean when you are tigging, I reckon for good welds it needs to be JUST as clean for mig.

Any contaminants will give you porosity and nasty welds.

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I've seen worse from guy's who think they know what there doing.

I remember doing vertical up for the first time about 20 odd yrs ago, making mortar bomb proof military bases lol, a bit of overkill on a chassis with a MIG though.

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Clean clean clean.

 

A really good welder will produce poorish welds if surfaces are not clean, so help yourself and clean clean clean.

 

DO NOT use grinding discs, they leave embedded bits in the steel, use a flap pad thingy - looks like a series of layers of sandpaper glued around the disc, use a corase to get fairly good, then a fine, then wire over with a cloth before starting.

 

Thats, and a decent qulaity helmet are 2 x things that can jump you ahead in doing better welds.

 

Nige

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Wow! Thanks everybody for the advice. I need to revisit my prep I think! :)

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By way of comparison, this is one of my axles prepped for a spot of welding:

2006-08-13-19h56m11.jpg

A long time spent with the grinder, first using a wire wheel to get all the military underseal off, then the paint, then flap wheel down to SHINY metal for a good area all around where the weld is going to go. There was no rust, but if there was you need to get it ALL off, not just back to "smooth" but back to BRIGHT SHINY metal.

Here's similar work going on on my chassis:

2006-07-14-12h22m07.jpg

And yes, I did wire-brush an ENTIRE 109 chassis back to bright metal - took days and about 10 wire wheels plus 3 dead angle grinders.

  • Haha 2

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That's what warranties are for, right?

  • Haha 1

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A D2 chassis can vary massively in steel quality over just a few feet it seems so that may add to the fun if you suddenly find you are poo at welding another patch on somewhere else.

 

my advise would be to get them mot passable for two years and start saving for a new chassis.

 

will.

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On 09/05/2018 at 2:49 PM, FridgeFreezer said:

By way of comparison, this is one of my axles prepped for a spot of welding:

2006-08-13-19h56m11.jpg

A long time spent with the grinder, first using a wire wheel to get all the military underseal off, then the paint, then flap wheel down to SHINY metal for a good area all around where the weld is going to go. There was no rust, but if there was you need to get it ALL off, not just back to "smooth" but back to BRIGHT SHINY metal.

Here's similar work going on on my chassis:

2006-07-14-12h22m07.jpg

And yes, I did wire-brush an ENTIRE 109 chassis back to bright metal - took days and about 10 wire wheels plus 3 dead angle grinders.

Ever tried polycarbide discs John? Friend put me onto them and although not cheap boy are they good at getting rid of paint and rust.

Was really struggling with wire discs to get the paint of a pair of 88" sides and flap discs were too aggressive. Three polycarbides got all the paint off both sides.

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15 hours ago, Ed Poore said:

Ever tried polycarbide discs John? Friend put me onto them and although not cheap boy are they good at getting rid of paint and rust.

Was really struggling with wire discs to get the paint of a pair of 88" sides and flap discs were too aggressive. Three polycarbides got all the paint off both sides.

I have, they wouldn't dent 30 years of gunk and military bitumen underseal and they wear out really fast - you've gotta get a wire brush and really put some pressure on it, hence 3 or 4 burnt-out grinders. Possibly could've used a hot air gun & scraper for some of it as a start but we had grinders and wire wheels :P

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8 minutes ago, FridgeFreezer said:

I have, they wouldn't dent 30 years of gunk and military bitumen underseal and they wear out really fast - you've gotta get a wire brush and really put some pressure on it, hence 3 or 4 burnt-out grinders. Possibly could've used a hot air gun & scraper for some of it as a start but we had grinders and wire wheels :P

Petrol and lighter...

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