help with mig settings!

[minidave]

Hi all

I have this mig welder which i did a lot of research before buying and im struggling to weld thin sheet metal together. I took it to a classic car specialists and they set it up and provided a bottle of gas (2% oxygen, 6% CO2, 92% argon).

I am welding some repair panels on a mini and im practicing with thin sheet but cant stop blowing holes. After trying there setup i played with wire speed and amount of gas but nothing will stop the blowing!

Hope someone can help

Dave

 

[SiPMerlin150]

Hi, for thin sheet its best to start of with the minimum settings, it looks to be a set with four possible settings. Also remember that the wire speed is going to alter the current settings also. Set it to MIN 1 and set the wire speed to the lowest and slowly increase it until you have a steady buzzing arc that isn't stuttering.

You wont get good runs on thin metal as its inevitable that you will burn through the thin metal. When you weld a car it will always be in small 'stitches' to reduce heat input, thus reducing distortion.

The lowest I've seen a MIG set go is 25 amps, which is ideal for car body work.
Wire wire diameter size have you got there?

 

[minidave]

Im using 0.6mm wire i think. May be 0.8 but it came with the mig. I currently have the settibgs to lowest possible. Am i using enough gas? Will that prevent holes being blown?

I can do really good spots/straight lines with good penetration but its joining 2 or more pieces together

 

[SiPMerlin150]

Do you have a regulator that measures how many litres per minute? Ideally 10-15lpm is a good flow to start of with. If you have not enough gas, your welds will look like the inside of an aero bar and be full of bubbles and holes. When you say you have trouble joining one or two more pieces together, you need to have both pieces either overlapping of straight up to one another with no gaps. Keep it all tight and make sure theres no rust on the metal. Short bursts of weld of one second each should be enough for thin metal.

 

[keith19]

Lots of good advice from SIPMerlin there!
Try to keep the job cool by spacing the short tacks, as advised above. Thin metal needs no encouragement to blow through at anything more than a touch of the arc. The diagram below might help when tacking in a panel.

 

[mike 109444]

Try a piece of copper or ally as a backing to soak up some of the heat and prevent blow through. On slow wire feeding (and smaller welders) try and keep torch cable as straight as possible to get an even feed. When you cut out a section on the rusty car allow an extra 1 inch then you will have a piece to practice welding it to a new piece. The spool of wire in your welder should be marked as to weather it's 0.6 or 0.8 wire and you should have the matching tip in torch and the wire feed roller set correct way round for the wire being used.

 

[rikrobson]

I've often found that the car body work you are working on is ALOT thiner than you thing and thus blows through. in that case i stich round the hole nade and fill it up with weld. The proces being to add to the lip made with the blow though.
The other problem is that the rust you are replacing is still on the back of the car panel or removing it has thinned the metal out. In this case you need to cut back further to good metal. It usually alot more than you think. No REALLY alot more than you think. no still keep going. Yup getting there now. now then cut back just a bit more and then make the patch panels.

The best advice is to just tack with wee one second spots. If you try to bead you will more than likely blow through. Remeber the longer to apply the arc the more heat you are putting in. There is less metal to absob the heat in thin metal and thus it blows through, or in reality melts back to the weld pool which has blobbed up on the edge og the panel.

Once the panel has blown though and there is a lip of blob. you can stitch on this to fill it.

Learned most of this welding mondeo sills, which are particularly thin and rusty!!!!!!


Hope this helps

 

[keeny]

hi mini dave
your settings on the mig in the picture is about right, your wire speed
shud be about 4 to 5, but depends how your wire speed works like on some models
3 might be faster than 4 on different models, one,s you get this right most important
in my 20yrs of welding experience is your hand speed the way you handle the torch
you want to practice this on some waste metal, hope this helps.....