Slow but sure progress

short length of time .Go and see a friendly Pub Landlord and get a big bottle of CO2 and then buy a suitable regulator from a Motor factors. However once you have used Argo shield or what ever its called you will never want to use CO2 again. My bottle costs about £50 a year rental plus about £30 a refill from BOC............ incredibly cheap compared to disposible bottles. steve the grease

>

I use CO2 at present without a lot of problems apart from the idiot holding the gun, my brother used to use pub gas but he was shown some paperwork by the landlord which stopped him doing it, there was something in with the gas which messed the welding. I suppose I shall have to speak with BOC.

Martin P

R L Driver wrote:

La vostra grammatica non è molto buona!!

Peter

-- Peter & Rita Forbes Email Address: snipped-for-privacy@easynet.co.uk Web Pages for Engine Preservation:

Not my fault, thats how the Web translator converted it like :-))

Mart> >

I used to have a MIG when I couldn't afford cars that didn't need welding for every MOT! I ran that on proper CO2/Argon mix on a rental contract as it was the only way to get a decent job (Air Liquide - fiver a month rental and I only used one full sized bottle in over two years). For something like an engine trolley I would recommend an arc welder and some decent rods. MIG was OK for the thin stuff, but unless you have a high power industrial plant, not good on penetration on the thicker stuff.

Just my two-penn'orth, I'm sure others will have different preferences.

Regards

Dan

I reckon that for straightforward welding of trolleys and the like, where the metal is of a decent thickness, then an ordinary stick welder is going to do all that you need, and without the cost of gas bottles, disposable or otherwise. I did once try a Mig with CO2, and it was OK, but the proper Argoshield stuff makes a big difference.

Regards

Philip T-E

I'd agree with Dan, for heavy channel you're going to need 120A-150A and a decent rod, but a big Mig would also do the job of course.

Our standard stick welder goes to 140A (SIP140) and Philip has a small Mig welder which I don't use at all.

Peter

-- Peter & Rita Forbes Email Address: snipped-for-privacy@easynet.co.uk Web Pages for Engine Preservation:

Gentlemen,

My Mig is 130 Amp unit which is more than capable and the material I am welding is 2 - 3mm thick with chamfered edges, you build up from the bottom of the weld as you go. You had better start worrying as "ALL" cars & vans etc are constructed using Mig welders and spot welding guns, about one every 150mm :-)) A Mig will give a very good penetration if the job is prepared correctly and the weld is cleaner than with a stick welder whose penetration is also only as good as its penetration and there is no slag to clean off. My only problem is the cost of the disposable gas bottles. Welding equipment regardless of type is only as good as the TWIT holding the gun and without regular use I can weld crap as good as the next man :-))

Mart>

I'd definitely agree with that, however I would say that cr@p MIG is worse than cr@p arc. Are you using the MIG indoors? Even the slightest bit of wind can disturb the gas shield.

Regards

Dan

Inside garage with door shut to keep out cold :-))

Mart>> Welding equipment regardless of type is only as good as the TWIT

Hi Martin, As others have said, dump the disposable bottle route and get something bigger. I use a pub bottle and find it's OK. I have never used Argoshield yet but I'm told it's better. For a trolley, I would use a conventional stick welder. This will give good penetration and is easy to use on the flat. No problem with a trolley but impossible on a car. That's when MIG is excelent. Beware of the cheap stick welders. They work but only just. Their biggest drawback is low electrode voltage. I recently upgraded to an Oxford oil cooled welder and it's a joy to use. My little cheap air cooled job wouldn't strike at much below 90 amps due to the low voltage. The Oxford will weld down to about

25 amps perfectly reliably. The downside is that it's b***y heavy. The modern inverter welders look really good and are very portable. I havn't tried one yet though. One final thought. Do you keep your welder in the house? A major cause of poor welds with MIG is the feed wire going rusty even though it's copper plated. The rust doesn't conduct electricity so you get a spluttering arc.

John

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Martin, What wire size does your MIG use? I could be wrong here but I was taught that if there isn't enough heat input, the weld doesn't heat the parent metal beyond the surface. When this cools, it contracts and either stresses or cracks. That's where a stick welder scores over a small MIG. I agree that the skill of the welder is a big factor in weld quality, that's why welders are coded and rechecked every few years. However, some forms of welding are easier to use than others. MIG is one of the easiest. If your welds look like bird droppings, there is something wrong. I suggest either rusty wire or dirty metal. MIGs don't like arc shield contamination.

John

Camp> Gentlemen,

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In message , John Manders writes

MIG is notorious for the welding defect known as "cold lap", or lack of fusion. The underlying parent metal isn't fused at all, and the weld metal just sits on top of it like a little casting.

MIG has two modes of operation, "dip" transfer, and "spray" transfer. The dip mode is far more common on thin sections and with hobbyist equipment. In dip transfer, the wire advances out of the torch nozzle until it contacts the work piece, the wire tip heats up until it is molten, and a 'blob' falls off into the weld pool if you are lucky, or on to the stone-cold or possibly luke-warm parent plate if you are not... If you see little globular lumps of spatter and 'bird shit', possibly with little bits of wire sticking out, then there just isn't enough juice. Even with dip transfer, when it is working properly, the melting and falling off of the blob happens many times a second. If you can't see a weld pool on the work, then the work is not hot enough for fusion to occur. The reasons for this can be manifold, but not enough current is favourite. Too fast a wire feed and too quick a torch displacement can also be culprits.

With spray transfer, the wire leaves the torch nozzle, touches the work piece and vaporizes, leaving an arc burning between the end of the wire and the work. If you have the wire speed and current right, the wire is advanced at exactly the same rate as the wire is consumed by the arc. The vaporized wire is deposited in the weld pool as a stream of minute droplets that 'fly' down the arc as a spray. This does require fairly hefty currents (300+ A) and is usually employed for thicker sections rather than car bodywork.

With any welding, practice helps, and MIG is no different. Personally, I'd want to weld offcuts for an hour or two before trying a trolley.

Regards

Pete

Have tried the pub bottle route, no good. BOC charge me about £50 a year bottle rental and around £30 for a refill. I use around a bottle a year doing all my engine work and a few gates and railings. The gates and railings pay for the rental and the gas I use for the year, so everyones happy, they get the railings on the cheap and I get my gas paid for. Easy really !!!

Cheers, MartinH

There speaks a man who has obviousely worked with automated welding systems like myself.

Mart> In message , John Manders

Trolley basically made now, I do have a good hobby stick welder for big stuff but dont consider my Mig incapable.

Mart> Have tried the pub bottle route, no good. BOC charge me about £50 a

I remember the only engine trolley I have made. I bought the Petter home on the trailer and it was too heavy for me to lift off. I had to make the trolley to let me wheel the engine off down the ramps.

John