new to mig welding - patching attempt!

[Nightwolf]

Hi all im new to the forum and to welding. Ive just bought myself a clarke 151en mig welder running gas. Ive bought myself an 67 camaro restoration project so will no doubt be doing some patching! Ive been practicing on some 1mm sheet metal with mixed results. I started off doing loads of tack welds then tried the stop start method. Im unsure about the penetration, should you be able to clean up the back side and it be invisible or will there always be a 'seam'? Also, when cleaning up the welds I ground them down then used an 80 grit flap wheel to flatten it. I ended up taking too much of the base metal away before getting the welds down. How do you make it look 'invisible' without it going wavey. Ill put up a few pics of either side. Thanks in advance!

 

[redwine300]

Hi Nightwolf, welcome to the forum mate.
As for penetration, Personally I would be looking for equal amounts of weld protrusion on both sides.
As for grinding back flush, I would only do this for aesthetic reasons really, say on the outside panel of the car. This way you will retain maximum strength.
I too found it very difficult to grind my welds flush when using flap wheels, I ended up getting the majority of the weld down and then switched to a hard grinding wheel so as to pick off the high spots and then finished off with a dremel.
Any chance of some pictures of your project?

Some usefull links..

http://www.mig-welding.co.uk/power-settings.htm

 

[Jim Davey]

A DA sander with 6" 40 or 60 grit discs works well for flattening off a panel once the high spots have been taken care of with a flap disk. The problem with flap/grinding discs is they remove more stock when stationary, so every time you stop and change direction they leave a tiny low spot.

 

[steveo3002]

i grind them near flush with a hardstone held on its edge..being carefull to try and not touch either side , once its down almost flush use the flap wheel

 

[Wendelspanswick]

Contrary to most peoples belief there is an acquired skill to using an angle grinder, as already said above I start with a grinding disk held at about 30 degs to remove the majority of the proud weld avoiding touching the material on either side and then switch to a sanding disk or flap wheel.
Getting your panels flush when tacking is a must, on critical pieces I use a 6" rule just to make sure.
Also be careful that as you weld the seam doesn't form a shallow V, if it does you need to remove most of the surplus weld, dolly it flat and then finish sanding flat.
A lot easier to do with TIG rather than MIG.
With regards to the back of the panel I am happy if there is little or no trace of the panel edges visible after welding, if you can see sharp panel edges your penetration is to shallow.

 

[Nightwolf]

Thanks for the replies, some good things to consider. As for penetration, how would be the best way to improve it. More heat or longer on the trigger for the tack? Cheers

 

[Nightwolf]

Ok todays results. I tried the pulsing method on a higher power and had some good penetration. I then tried filling in between tacks which seemed to work better with good penetration. Couldnt see if it warped that much cus the panel was wavey already! Gave it a quick grind and flap but still found it was making a W shape in the metal. Think I need to give a flat sand disc a try.

 

[Nightwolf]

Ok so been out in the dungeon again. First off tried some plug welds, first went ok but second one I missed half the hole so had to fill it!

Is that enough penetration for say a floor pan weld? Next I had a go at the seam.

then had a go at closing up the distance between the tacks

then went on to try more plug welds.

Would appreciate any input on where im going wrong etc will be great!

 

[Jim Davey]

They look good to me, it appears you had a gas flow issue (not enough would be my guess, or starting to weld before the torch was purged) as there is some porosity, but apart from that they look perfectly acceptable (far more so than the average MOT repair)

 

[Nightwolf]

Its possible there wasnt enough gas. For some reason machine mart only had a regulator with one dial on in store so I dont have a flow meter! Im just turning it up til I get a hiss, not sure how hissy its meant to be! Ha is there somewhere you can buy the flow gauge to fit onto my regulator? Cheers

 

[Robotstar5]

You could get a "pea shooter" flow gauge, fits over the shroud so measures the flow where it's needed

 

[Nightwolf]

Ahh brilliant thats what im looking for!

 

[Nightwolf]

Which bit do you think looks porous? Are we talking about the dips in the weld?

 

[Robotstar5]

Ahh brilliant thats what im looking for!

Just remember to slacken wire feed rollers when using it!

 

[Nightwolf]

Can I not just use it with the welder switched off? Thats how I listen for the hiss at the mo.

 

[Robotstar5]

Can I not just use it with the welder switched off? Thats how I listen for the hiss at the mo.

You're right, I'm thinking of welders with the gas solenoid inside the set, need power on to operate

 

[Jim Davey]

Which bit do you think looks porous? Are we talking about the dips in the weld?

No, it's the holes in some of your plug welds.

 

[Top Ghia]

Hi sorry to hijack the thread but im interested in the pea shooter, well more interested in correct flow rates really. How do you judge the flow rate?

Thanks.

PS Im a nubie too but would be more than happy if my welds looked like yours, well done

 

[mike 109444]

There should be a scale marked on the pea shooter indicating the flow rate in liters per minute "lpm" usually between 8 to 14 lpm