#1 you need a gap for your mig joints and you can get a gap with a spacer clamps. #2 you need to get rid of all the rusted metal. #3 you need to clean your metal from any contamation that will ruin your weld. burning through is a sign of getting too hot or dirty metal. Use a copper backup I like to use old copper sheet or buss bars to back up my welds. Again TACK, TACK, TACK, TACK! You must move around to keep from warping your metal. I have used Tri Mix and it works well but also have had good welsd on 80% 20% mix on heaver metal I used straight C-02 another thing keep your shielding gas from blowing away when welding by putting up a barrier around the area you are welding.
It doesent need to be real close to the weld just to protect the breeze or wind from a fan OR! If it is rusted use a grinder with a wire brush to get down into the rust pits or if too bad use a new piece of metal cut to fit the rusted area. I have learend a long time ago you must think outside the box when reworking metal. The previous post have nailed it very well but the heat will be the cause of burning through most of the time along with that dam rust contamation. Try using some Metal Prep # 79 to clean the area if it is had rust. Then be sure to wipe away with a wet rag and let dry then weld it.
There is a very good book out by Eddie Paul called Paint & Bodywork Handbook. This book can be picked up at Barns & Noble. Very good book on welding and other processes you will come across when working with sheet metal body parts. I picked it up to reforce what I have learned about leading after welding certain areas of your truck. $25.00 + the tax. Well worth the bucks and a wealth of info from some great pros.
I hope this helps some of you in your endevors been fabing for a long long time and still learning.
62Blue
Don
Last edited by Don G.; 07/01/2009 8:07 PM.
