I've had my MIG for the last 5 years, and generaly I can get very good welds, although the vast majority of work has been on car bodywork.(I owned a mini...)

This eveing I have been welding up the front suspension mountings on the Locost this evening, and I've had a few problems. If I try welding upside down (i.e. nozzle pointing up), the arc starts and stops (almost like feed rate was wrong) and the weld looks very lumpy and generaly crap. The nozzle also gets filled with crud very quickly.

However, with exactly the same settings I can produce something that makes me feel like a welding god as long as I am welding with the nozzle either pointing down or sideways.

I also have problems trying to into an acute angle. The arc seems to jump from one side to the other, and I end up with a very messy looking weld again.

Any suggestions on improving my technique? (apart from getting a grown up to do it )

i have the same trouble. i cant weld upside down, so i turned the car over to finish it. And as for welding into tight angles, the arc will try to take the shortest route. maybe clean the shroud and screw it back to make the wire tip closer to the piece.

Having said that you've been welding much longer than me so feel free to ridicule me!

sounds like a dodgy cheap mig set or your shroud is that stuffed it's arcing out when you touch the steelwork with it.

Fit a new liner,tip and shroud

Could be one of a few things,

You may be in an awkward position, and the liner may be kinking due to excessive bending causing the wire to be pinched.

The gas supply may be kinked the same way

The earth connection may not be as good as it should (always the first thing I check when having problems)

Always get the nozzle as close to work as you can, get the torch as close to 90 degrees as you can, if all else fails, wind up the power and weld faster!

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Originally posted by undecided
sounds like a dodgy cheap mig set or your shroud is that stuffed it's arcing out when you touch the steelwork with it.

Fit a new liner,tip and shroud

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Originally posted by MikeRJ
To be honest, I could leave the upside down bits until I'm in a position where I can turn the chassis over, just impatience and my rather poor memory meaning I'll probably forget to do them!

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when you are welding upside down you are not getting enough gas around the weld (if any). the gass stops ,or reduces oxidation of the metal (the crud build up) if you are going to try to weld upside down you will need very high gas flow as argoshield is denser than air and will sink.

Thanks for the tip Simon, will give it a go!

BTW, does anyone know where a non-business user can get hold of the larger, refillable bottles, and how much they cost? Paying £7-8 for the small disposable ones really up's the running cost.

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Originally posted by MikeRJdoes anyone know where a non-business user can get hold of the larger, refillable bottles, and how much they cost? Paying £7-8 for the small disposable ones really up's the running cost.

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They mix in Nitrogen with pub gas as well. It seems to need more power than Argon mix and it spatters a lot when I've used it.A soft drinks firm fills bottles for a bloke near us and he does them at £10 exchange,they tend to use just CO2.

I use fire extinguishers, i have a gauge and adaptor to fit a pub bottle and it will also adapt to a large C02 extinguisher.
My local fire extinguisher firm supplys extinguisher bottles with screw down valves fitted and charges a tenner for a refill. I presently have a few extinguishers with standard handles and just cable tie the trigger down.
Paul.

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Originally posted by JH

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Originally posted by MikeRJdoes anyone know where a non-business user can get hold of the larger, refillable bottles, and how much they cost? Paying £7-8 for the small disposable ones really up's the running cost.

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Pub Gas? a decent adaptor hose and (if you don't already have one) a Regulator with a gauge will cost about £30.

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DavidM - 14/6/04 at 10:02 PM

If the settings you are using for overhead welds are the same as those for downhand then you've got it set up wrong.

Lower voltage and current settings and introducing a slight weave will help prevent the hot metal dropping into your shroud (or boots) due to the effects of gravity.

Overhead welding is the most difficult technique to master so you would probably achieve better results by turning it over.

Turning up gas will make no difference as it comes out under pressure anyway. As long as it shields the weld, any more is just a waste. If it's not shielding the weld you'll get porosity.

To reach into acute angles, cut a spare shroud short so that the tip protrudes up to 5mm. For really acute angles also increase wire feed, and thus amperage slightly. This helps overcome the current drop resulting from the greater length of wire sticking out of the tip.

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Mark Allanson - 14/6/04 at 10:17 PM

Overhead welding should be no different from downhand, problems will only happen if you let the torch to workpiece distance increase.

When working in accute angles, Dave is right, cut and old shroud into a point so the gas is trapped and will flow into the weld, although the power setting should be the same

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DavidM - 14/6/04 at 10:50 PM

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Originally posted by Mark Allanson
Overhead welding should be no different from downhand, problems will only happen if you let the torch to workpiece distance increase.

Sorry Mark, but I disagree.

The characteristics of a downhand weld pool are different to positional welds. Penetration for an overhead weld will be greater than a downhand weld for the same voltage and current settings. The molten weld pool will also be less stable due to the effects of gravity giving the classic bunch of grapes weld. This is overcome by correct settings and weld pool control techniques.

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Mark Allanson - 15/6/04 at 06:30 AM

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Originally posted by DavidM

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Originally posted by Mark Allanson
Overhead welding should be no different from downhand, problems will only happen if you let the torch to workpiece distance increase.

Sorry Mark, but I disagree.

The characteristics of a downhand weld pool are different to positional welds. Penetration for an overhead weld will be greater than a downhand weld for the same voltage and current settings. The molten weld pool will also be less stable due to the effects of gravity giving the classic bunch of grapes weld. This is overcome by correct settings and weld pool control techniques.

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Whatever works best for you

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Mark Allanson - 15/6/04 at 06:34 AM

Dave,

Could you give us a summary of what wire speeds and powers for various weld positions? Such as uphand vertical, downhand vertical, overhead, downhand etc - It would be a real help to us amateurs

Thanks
Mark

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Peteff - 15/6/04 at 10:20 AM

I find overhead welding easier if I am working away from myself. I do tend to leave the settings alone and angle the tip a bit more so I can see what I'm doing. If I do get runners I sort them out with the grinder . This is only on thin stuff like the tube or car floors (20g). It gets easier the thicker your material. I use .8mm wire for everything as I find it more controllable if this has any relevance. On the tight angles Joel mentioned my tactics are to use a cut down shroud, build up one side, then the other and then join them together in the middle. I have been welding and burning for many years (30ish) including gas, tig(many years ago), arc and mig and I've never had a major disaster yet. Wire speeds and power will be down to personal preference and individual machines due to calibration differences. If I use my 170 over 4 with the wire speed over 3 it will blow the chassis away whereas a 120 will need full power. I never weld uphand vertical with mig unless the material is over1/4" thick, then I find a slight gap and using a fill in(side to side) works best for me, like with arc.

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locoboy - 15/6/04 at 10:23 AM

Meeeeeawwwww

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Peteff - 15/6/04 at 01:01 PM

was it a cat impression?

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alainmengoli@hotmail.com - 15/6/04 at 01:11 PM

I own a couple of bars and pubs and they mix gas you guys are talking about is commonly used but all pubs should have co2 a nearly all cocacola/pepsi machines use it. Ended up lending one to Ian at Stuart taylor as he ran out.
Plus all new largers i.e. budweiser and interbrew products are starting to use co2. If they add oxygen it will be posted onto the bottle and any co2 with added oxygen usually is within indutrial tolerance i.e. same as the diposable ones.

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DavidM - 15/6/04 at 11:25 PM

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Originally posted by Mark Allanson
Dave,

Could you give us a summary of what wire speeds and powers for various weld positions? Such as uphand vertical, downhand vertical, overhead, downhand etc - It would be a real help to us amateurs

Thanks
Mark

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No offence intended Mark.

Let's agree to disagree.

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type 907 - 16/6/04 at 05:58 AM

Hi All

Anyone want an empty bottle?

Free to a good home.

Distillers/Allied Breweries, male thread.

Most landlords will swop for a full one
but it can be difficult to get hold of your
first one. I was going to get a "squirter"
but in the end bought a TIG.

Paul G
Rescued attachment Co2 bottle.jpg

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