rust, welding in new sheetmetal, and rust again?

[babowc]

sorry for the confusing topic title.anyways, i was wondering.. wouldnt cutting out a rusted spot on a car, then replacing it with new sheetmetal actually bring more rust?

situation:

rusted spot on door,cut out with a flame torch which introduces "concentrated" oxygen unto the spot where its been cut.. [wouldnt that ^ cause the surrounding/cut-out area to be susceptable(sp) to rusting eventually?]weld in new sheetmetal, bondo, primer, paint, etc.

[sith_killer_99]

Nope!

I took 3 years of autobody in High School and the best way to get rid of rust is to cut it out like the cancer that it is!

All metal rusts eventually.

What I recommend is replacing the rusted metal as you mentioned, however the key is getting all the rust. Then weld in the new metal, grind it, bondo, sealant/primer and re-paint.

BTW, Adams City High School was the only High School in the State of Colorado to offer Autobody as an elective when I graduated back in 1993!

[babowc]

wow..you graduated when i was 6.. hahaha DAMN!

anyways.. back on topic. does it matter what you cut it out with?since fire = oxygen + gas; rust = oxygenated surfaces + iron.. zinc.. something.. i forget.

[sith_killer_99]

I would recommend cutting it out with a mechanical cutter or a small grinding wheel and then welding the new piece in with a mig welder. Mig welders use argon gas shielding and an electric current for the welding process.

For automobile metal replacement you can use a 110v mig welder for most applications. You should be able to rent one from a local equipment rental store.

Be sure to remove any material that could catch fire from around the area being welded. I know it sounds obvious but you would be surprised by how many people make that mistake. You will want to drop the gas tank as well!

Here are a few sites for mig welding to get you started.

http://www.lincolnelectric.com...q.asp

http://www.eddiem.com/projects/mig/mig.htm

http://www.twi.co.uk/j32k/prot....html

http://www.weldingengineer.com/1mig.htm

http://www.thefabricator.com/A...D=929

Quote »you graduated when i was 6.. hahaha DAMN![/quote]LOL, you're just a young pup then!

BTW, my 240 was mfg. in 1993! It's funny, because we both probably have VERY different outlooks on the 240's. The first 240sx (S13) hit the streets in 1989, the year before I got my drivers license! You were 2 years old. For me that you be like having a car that first hit the streets in '76!

LOL, I guess I'm getting to be an old timer. LOL

I hope my advise helps.

[babowc]

wow.. haha you're old thanks for the info, i was confused about the whole cutting out/rust thing, but seems like you cleared it up for me very nicely!

thanks again!

[sith_killer_99]

Hehehe

Good lord, I'm only 31! Hehehe

I guess that seems old to some people.

[kainpabyeda]

Weld-through Primer is used to add corosion protection at the weld. When you're through welding remove the excess primer, not much'll stick to it.