welding critique please

[David Pozzi]

You might be able to weld thru primer using stick arc, but not a Mig. It has to be clean anywhere near where you are welding.

[kamaroman68]

Thanks guys for the reply's. Everyone seems to concur that it is contamination. What is the purpose of 3M weld thru primer? The metal was prepared perfectly.(Bare steel) I then coated it with 3M weld thru primer as the can states. Am I not supposed to weld where the primer is? I thought the purpose of the stuff was to prevent corrosion between panels. I did weld over this stuff so is it possible this is where my contamination is coming from?Again thanks for the reply's. Chris

[redss86]

3m's weld through primer is specifically disigned for mig welding. it is used on areas like pinch welds, and lap welds. you are correct in the fact that it is a corrosion resistant coating. when using it you will get extra spatter to start w/ but if you do a good hot weld then it will clean up. i wouldn't do ne wire brushing over the primer, as this will remove the coating. also, after you are done welding and dressing the welds, make sure you remove ne primer that will have filler put over it or will be primed over. i would strongly recommend using the primer between panels but you don't need it on the outside as it will get primed when painted. basically just follow the instructions on the primer, and have a good hot weld.

Yesterday 07:57 PM
Gordz32 We just finished our lesson on welding up at wyotech, last month, and what they stress the most is that you have a clean metal surface for welding and that you need to set your welder up properly, the best way to do that is to make some test welds on metal the same size as your project. Also, the perfect weld will sound like bacon frying. It looks as if your surface should be cleaned. Good Luck!

did you just finish the classroom lesson, or are you in the shop yet. i don't remember when they talk about weld through primer, but i know you will have to build a fake rocker panel out of sheet metal and you will be required to use the primer on it. don't remember if that is first or second phase, but i had to do sometime. that is unless they have changed things since i attended 4 yrs ago. good luck in school, and make the best out of it. from what i learned, you are only going to learn as much as the effort you put into it. what other classes are you taking/ have taken?
good luck,
joe