Repairing Rust Spots

[RDF]

Hey all, I've got a rust spot on my driver's fender (on the top, flat spot near the hood) that I was going to try to repair myself.  Take a look at the pics I've uploaded, 1 is the far shot of the spot and the other is a close-up so you can see the depth of the rust.  The other is my mig welder that I just bought this weekend (100 bucks at a garage sale, brand new in the box!).

My question is, do I grid down the rust spot and all around it until I get to solid metal, then weld in a good piece of metal?  I know I'll have to grind down the weld beads once it's complete, but I think I want to try to tackle this before it spreads.

Thanks!

[Steve]

I'm assuming that we're talking about doing this repair in two big stages. The first is repairing the rust spot. The second is blending new paint to cover the repair area. You might do the first and you might have a shop do the second. In any event, doing step 1 correct will make all the difference in the results of step 2. Also, you want to keep the repair area to a minimum...so, with everything you do, you need to keep the heat down to avoid warping and melting the existing paint on the fender.

1. Strip paint with a Roloc or similar device until you find good metal. Keep the heat down, work slow.
2. If affected area is larger than say 1/4" in diameter, you probably will have to fabricate a little patch piece and weld in the patch piece.
3. Cut out all rust. You may find it easiest to cut out a square or rectangluar section. In most cases, I would probably use a small cutoff wheel. Depending on the size of the area, I may even use a Dremmel cutoff wheel.
4. Make patch piece out of 20 gauge steel. Size piece so that there is about 1/16" gap between the sides of the patch piece and the hole in the fender.
5. Get a welder that uses Gas. Sorry...do NOT use that gasless welder on this repair. The heat will be too high...the welds will splatter...it will be a mess.
6. Use tack welds around the perimeter allowing metal to cool as you go. Make sure welds penetrate all the way through.
7. Grind with solid disc first, making sure to only grind the part of the weld above the surface. Finish metal work with Roloc discs of varying grits.
8. Mask off repair area....lay epoxy primer on bare steel. Do filler work. If someone else is going to do the blending, you might ask them how big of an area you can work. Fill work must blend gradually with the existing finish.


Good luck!

[RDF]

I'm assuming that we're talking about doing this repair in two big stages. The first is repairing the rust spot. The second is blending new paint to cover the repair area. You might do the first and you might have a shop do the second. In any event, doing step 1 correct will make all the difference in the results of step 2. Also, you want to keep the repair area to a minimum...so, with everything you do, you need to keep the heat down to avoid warping and melting the existing paint on the fender.

1. Strip paint with a Roloc or similar device until you find good metal. Keep the heat down, work slow.
2. If affected area is larger than say 1/4" in diameter, you probably will have to fabricate a little patch piece and weld in the patch piece.
3. Cut out all rust. You may find it easiest to cut out a square or rectangluar section. In most cases, I would probably use a small cutoff wheel. Depending on the size of the area, I may even use a Dremmel cutoff wheel.
4. Make patch piece out of 20 gauge steel. Size piece so that there is about 1/16" gap between the sides of the patch piece and the hole in the fender.
5. Get a welder that uses Gas. Sorry...do NOT use that gasless welder on this repair. The heat will be too high...the welds will splatter...it will be a mess.
6. Use tack welds around the perimeter allowing metal to cool as you go. Make sure welds penetrate all the way through.
7. Grind with solid disc first, making sure to only grind the part of the weld above the surface. Finish metal work with Roloc discs of varying grits.
8. Mask off repair area....lay epoxy primer on bare steel. Do filler work. If someone else is going to do the blending, you might ask them how big of an area you can work. Fill work must blend gradually with the existing finish.


Good luck!

Awesome!  Thanks a bunch.  I've got a quick question about the welder.  This is the only one I have or have access to.  it has a hookup for an Argon gas tank, so I can use gas to minimize the splattering, would this work?  I hope so, b/c I don't have access to any other welding supplies if not.

I will do my best with the paint, not too concerned right now about matching paint, just want to get started on repairing the body, then send it to the body shop for finalizing.  I'm trying to save as much $$$ on the body work as I can, besides, I've always wanted to learn how to do body work.

[torredcuda]

Most small migs are can weld two ways either using flux core wire or regular wire with a shielding gas.I have never used flux core but others say it works OK but if you are set up for it I would reccomend getting a bottle of Argon/Co2 mix.Find some scrap metal and practice adjusting heat and wire speed for a good weld.Also cover any glass or other parts from welding and grinding spatter as  both will burn/pit glass.

[Steve]

IF it has the gas option, you're golden. Download instruction manual (if you don't have one) and verify that you have the correct trigger assembly to support gas.

I recommend the "Twenty-Guage" brand of welding wire. It's .025 solid wire designed to "act" like .020 wire. It's great for body work because it works at lower temperatures and is easier to grind than standard wire.

[dougs bs23]

its an easy repair, just take your time and things will work out great for you.  As for your welder,,, you may need to change the gun for gas.  Go to your local welding supplier, they will be able to help you set it up and i would suggest a good flow meter as well,, Dont know what the costs are in your area but to purchase an 80 cu.ft bottle may cost you around $60.00 . I would buy it instead of leasing the cylinder then all you do is return for a fill up and pay only for the gas. Youll also need your 020 wire, correct size tips and i would also buy an extra nozzle or two just to have on hand. Oh ya,, an aoto darkening helmet too,  Good luck and happy welding