This may be dumb and maybe there is a reason it isn't done so enlighten me..... I have started***** welding my panels in. I have noticed that the back side of the weld (when welding from the outside of the car) is dang near smooth and will require very little grinding compared to the outside. Everything I have seen other guys do is spot weld on the outside and grind them down. Just seams like it would save some time in areas that you can access the backs of the panels. Especially in areas where you don't grind the backside of the weld anyhow? The entire inside of my cab will have some kind of sound insulation over it and no one will ever see the welds so why grind more than you have too?
That's really what it comes down to. Access. I do it both ways depending on what suits my needs better. Sent via Illinois Bell Telephone Company's Car Radiotelephone
First and foremost, you should set up your welder for a full penetration weld. Theoretically, when you get done with your Mig welds, both sides should ground smooth to replicate the original panel as much as possible. (access permitting) In much the same way as a lapped panel will show ghost lines due to differing expansion rates, having a thicker area due to excessive weld will also promote the same effect. Having more weld proud on the outside makes it more accessible for dressing the weld smooth, to help prevent this from occurring. To eliminate the grinding/cleanup typical in MIG welding, Tig or O/A gas welding are a good option to minimize weld proud. If Mig is your only option at this time, EZ grind or ER70S-7 will give you a softer weld for easier planishing and easier grinding. I've found that the "wetting" characteristics of the ER70S-7 also result in a flatter weld, for less clean up..
I am getting full penetration. It just leaves a nice clean barely raised bubble on the back. The ghost line makes a lot of sense. Kind of like large equipment when you can see the weld through the steel plates on it... Posted using the Full Custom H.A.M.B. App!
pictures? so we can see ? seriously it sounds like your better at this than most (self included ) might make a great tech article ,
ive done it many time as long as your getting good penetration,you will have no problems I also don't grind down the weld on the back side,never had gost lines show through, one of the major causes of distortion is from grinding down the mig weld,
This thread shows front and back views of the welds, etc..... http://www.jalopyjournal.com/forum/showthread.php?t=767491 .
I use a wire called easy grind. It's a little softer so you can hammer and dolly it some .grinds pretty good to. I've often wondered about the op's question to.
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