How to MIG weld

[JohnD]

Unkel, like any conversation, over beer or coffee, these are not organised ( or disorganised!) debates,where a chair may stop any deviation.   They meander, they branch off, they wander and all to the good!   

Please don't seek to police our chats!  We learn so much more this way.

John

 

[Unkel Kunkel]

Wouldn't dream of doing that, John  - as I said the deviation is fascinating and i’m no more organised than the trajectory of the sliver  sphere in a pin ball machine, it’s just that we’re not helping Attwood 65 with his question.

[JohnD]

But I think we have, Unkel!  Courses, materials, and above all, practice!

May we not diversicate now?

John

[attwood65]

Thanks for all the replies. I have got some sheet metal from Frosts which seem good.

Any views, 6mm, 8mm or 9mm welding wire for body panels?

Removed the rear body tub the weekend. Now for plenty of practice.

Edited November 6, 2023 by attwood65

[Colin Lindsay]

10 hours ago, Unkel Kunkel said:

Fellow highly-esteemed ‘ Triumphants’

May I humbly  point out  that  we seem to have not only drifted  a little from the path of the  subject , which was a question entitled ‘ How to Mig Weld’, we have now veered  off down an  unmarked track on another subject.

-fascinating as it is

Apologies as one of the major culprits however: using the correct type of metal is also quite important. 

[Iain T]

4 hours ago, attwood65 said:

Any views, 6mm, 8mm or 9mm welding wire for body panels?

0.6mm should be fine but if you can only get 0.8mm that's OK. As everyone has said its practice. I could hear a good weld without having to look. If its thicker material or plate always chamfer ends never butt weld as its weaker. With old sheet steel it will be contaminated so expect a lot of splatter or even melt the edges. 

Iain 

[Colin Lindsay]

28 minutes ago, Iain T said:

As everyone has said its practice. I could hear a good weld without having to look.

Everyone tells me to listen for a sound like bacon frying. Is that streaky, thin-cut, thick-cut, smoked or maple? I've never yet heard a sound like frying bacon but I've heard an electrical sound like a short-circuiting battery.

[68vitesse]

Found 0.8mm wire, presumably you are not using gasless, the most useful size even with 20guage using a pulse weld technique to reduce heat build up.

Colin, unsmoked back from a proper butchers which doesn't exude water and that white stuff is the best match IMHO.

Both suggestions from my experience as a very amateur welder, best tool after welding is an angle grinder or powerfile, can make things look so much better.

Regards

Paul

[Iain T]

No it's not bacon frying, it should be an even electrical arcing sound however on old contaminated metal it will cough n splutter. I've seen many a nice looking scalloped fillet weld break when tested due to lack of penetration into parent metal. Do some trial welds then try and break the joint. Tack weld everything first. IMHO gas welding thin gauge metal is best but is much more difficult. 

Iain 

Edited November 6, 2023 by Iain T

[Josef]

1 hour ago, Iain T said:

IMHO gas welding thin gauge metal is best but is much more difficult. 

I was intending to learn gas welding as I’ve been given a welding torch and cutting torch (former NCB kit!) but the price of acetylene is putting me right off, plus having two more gas bottles in the garage. 

[Iain T]

Lots of heat sink putty available to limit heat distortion. The price of gas is expensive now. I had three CO2 lasers that gobbled up pure nitrogen as a shield gas and had a cryocell for liquid nitrogen to reduce costs. I looked at compressed (clean) air (76% nitrogen) as was astonished at the price! The oxygen did oxidise the edge so pure nitrogen was best. For Mig welding we used Argon 20.

Iain 

Edited November 6, 2023 by Iain T

[Unkel Kunkel]

Frying bacon (in my experience)  is,   ‘ fizzle.. pops, pause, pop … pops.  fizzles, pause , fizzle  pauses fizzle fizzle…’ - which  is the sound of trying to weld unsuccessfully,  with poorly prepared  metal, wrong wire speed /Amperage”

Whereas hitting the well-tuned  mig setting is a more like a steady,  resonant continuous ‘ berzzz’ 

Edited November 6, 2023 by Unkel Kunkel

[attwood65]

Thanks to everyone who helped on this topic. Some great advice. Rear tub removed, panels and metal arrived, garage tidied, so it's now practice and then deciding if I remove the front bulkhead to fully paint the chassis....

[Iain T]

A hand joggle tool is a good aid. Loads on ebay

Iain 

[AlanT]

Your Clarke 135TE is an excellent choice. It's very forgiving for bodywork as it can run at low amps. Do get flap wheels for making sure metal is clean...makes a huge difference to the weld. 

Agree that an auto darkening helmet is essential kit...but so is a bright light so you can see to place the torch before the arc is struck...I have one of these as it's super maneuverable and lasts for ages between charges. https://www.screwfix.com/p/lap-rechargeable-led-work-light-1000lm/613KF?kpid=613KF&cm_mmc=Google-_-Datafeed-_-Electrical and Lighting?kpid=KINASEKPID&cm_mmc=Google-_-TOKEN1-_-TOKEN2&gclid=EAIaIQobChMI3JyEl465ggMVdGHmCh3ISg35EAQYASABEgIQgPD_BwE&gclsrc=aw.ds

Edited November 10, 2023 by AlanT

[Morgana]

Ensure you have proper penetration. MIG is a form of welding where it's easy to get a bead that looks good, but is all fur coat and no trousers. When practising, ensure you give as much inspection to the back of the weld as to the front. This book "The Art of Welding" from the Workshop Practice Series doesn't deal very much with MIG, but has some useful diagrams that are universal, and good resources for analysing where one went wrong.

Zintec from 'Metals4u' has been handy to have around, as it doesn't rust very quickly so can be stored in less than ideal conditions. A big vice, engineer's hammers, rawhide hammer, and an anvil can be helpful for forming rudimentary shapes. My partner made a metal bender from angle iron from an example shown on the MIG Welding Forum. Good for sill sections.

What gas are you using? Rent-free or a contract with Air Products etc.?

[Homersimpson]

11 hours ago, AlanT said:

Your Clarke 135TE is an excellent choice. It's very forgiving for bodywork as it can run at low amps. Do get flap wheels for making sure metal is clean...makes a huge difference to the weld. 

Agree that an auto darkening helmet is essential kit...but so is a bright light so you can see to place the torch before the arc is struck...I have one of these as it's super maneuverable and lasts for ages between charges. https://www.screwfix.com/p/lap-rechargeable-led-work-light-1000lm/613KF?kpid=613KF&cm_mmc=Google-_-Datafeed-_-Electrical and Lighting?kpid=KINASEKPID&cm_mmc=Google-_-TOKEN1-_-TOKEN2&gclid=EAIaIQobChMI3JyEl465ggMVdGHmCh3ISg35EAQYASABEgIQgPD_BwE&gclsrc=aw.ds

I have the Clarke 150TE which is basically the same as you don't use the top end of the welding power for normal car bodywork, i've had it a round 20 years and restored an S-Type Jag (1960's), two MK2 Jags, a VW Camper, a Frogeye Sprite plus loads of other welding with it and its been great.  Only issue I had was the torch wasn't great and after a few restorations and about 10 years I changed it for a slightly bigger one which I think was called an MB14.

I would also recommended the auto darkening helmet as it really helps.

As mentioned above the most important thing is to get the metal really clean and i've also found that getting the gas quantity right is important as having too little makes the weld poor.