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 Rust repair for a noob

 Created by: Haydn
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 Posted: Jan 26, 2022 05:41AM
 Edited:  Feb 9, 2022 05:18AM
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As far as tools go, I have a 24 inch Box & Pan Brake, which I find invaluable with sheet metal work. This tools bends sheet metal and can add multiple bends.

Lincoln welder with argon/CO2 gas. Electronic welding hood (this is the type that turns dark when you strike an arc).

Two DeWalt angle grinders. One with a thin cut off wheel and the other with a grinding, sanding, or other speciality wheels. There is a speciality wheel that is a flat stainless disc that shrinks sheet metal, in case you warp the metal. Having two saves a lot of time.

A good Jig saw that is able to cut a straight and curved lines using 36 TPI blades. Drills and various hand tools. Dremel with various bits.

Multiple sheet metal "Vise Grips" Brand, from a couple of long ones to the small 6Rs. Do not buy the cheap Chinese imitation tools.

Good eye protection, hearing protection, leather gloves. Optional leather jacket but be prepared to burn thru a lot of clothes.

All this is not cheap. I can't say if it will be an investment because all these items are expendable. I can't say if this will be satisfying either, all that depends on you. I can say without a doubt that it will be frustrating at times. Maybe satisfying for a moment before you tackle something else.

 Posted: Jan 25, 2022 02:55PM
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US
I don't have anything else to add here, great points have been covered.    But I bought a welding machine years ago.   It is a Lincoln 140C.  The difference between the 140C and the 140HD (Home Depot model I am told), is that the 140 HD has 4 welding settings.   The 140C has a variable potentiometer to control the amount of heat.    It is nice to me as you can really fine tune the power rather than just blowing through metal.     

I do not have the MIG conversion kit for it,  I just use Flux core wire.    Works perfectly for this kind of stuff.   I have welded MANY cars with this one.   Very robust, for not much money.

Michael

 Posted: Jan 25, 2022 09:43AM
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You guys are awesome - this is like a complete tutorial on sheet metal repair.

The collective knowledge in this forum is second to none!

 Posted: Jan 25, 2022 05:34AM
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CA
I think 6464s means to use the cardboard as template material to make shapes to cut patch steel. (Cardboard is difficult to weld!)

If your car is driveable, do one repair at a time. Avoid taking it all apart, only to discover the project is beyond your capabilities or time. That's how some Minis end up as basket cases... all the bits in assorted baskets, boxes and bags. Between repairs, you'll still be able to enjoy it.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Jan 24, 2022 09:16PM
 Edited:  Feb 9, 2022 05:15AM
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Perseverance- Don't give up. Don't give up. Don't give up.

Organization- Label everything; right down to the screws and nuts. Make a dedicated place to put everything. It will be a long process.

Patterns- I like to use the cardboard from cereal boxes, it's nice to work with, right thickness and cheap. Mostly everything you have recreate starts off flat.

Sheet metal- You will use 18gauge and 20ga mostly. The factory use the combination of the two, for example the boot floor is the lighter 20gauge because of the stamping of the tire well (heavy bends). I use stainless steel sheet metal. Create weep (1/8" or 1/16") holes in problem areas. When I replace the outer sills, I now slip a stainless washer between the inner and outer lap and plug weld them together. The water will continually weep out instead of rotting both the pan and sill.

 Posted: Jan 24, 2022 09:10AM
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I'm going to answer the questions that may or may not be in your post (and not having digested your entire post word-for-word nor having read the responses of others-- yup, I'm getting to that age...).

100% absolutely do NOT cut out the amount of original metal just to match the size of the repair piece you may have ordered. Cutting out an entire front floor pan section for an index-card sized hole in the outer part of a floorpan is a very very bad move.

Generic flat steel is your friend. Don't worry about using replacement panels for patches where they are not seen.

I absolutely do not recommend trying to butt-weld in replacement patches to try to get a flush finish, especially for undercarriage work. Nobody will see it and you are just trying to shore up weak spots and cut out rust to prevent it from spreading. I'm a big proponent of overlapping, drilling, and using plug welds first with the replacement metal being slightly thicker than the original metal to take the plug and not melt away. If you REALLY want to try seam welding afterwards, go ahead but do it in "stitches" and not one continuous bead, especially when you are still learning.

Spray can paints for covering floorpan and other "hidden" repairs is for people who want to get high in their garages. Get some brush-on rustoleum or similar to get a nice thicker layer of paint on the metal and surrounding area if you really want to protect it. Use some type of seam sealer around the edges of the metal repair patch where they overlap.

Zap- cool- Zap-- Cool --Zap-- Cool. Basically when the red glow starts to subside from when you stopped your zap, zap it again for about a "onethousandone" count. Repeat.

  Flux core is fine for starters. It splatters more but is much more forgiving on old metal that may have some rust on it. used craigslist welders are fine as well. 4 heat range settings is good (ie A-B-C-D) but you'll want variable wire feed speeds. recommended settings inside the lid are an excellent starting point. Best way to learn is to practice practice and practice on scrap metal.

A copper plate or "spoon" is excellent to hep prevent burn through when you are plug welding.

using pop rivets to hold your patch TIGHTLY into position is ok, then weld (zap) up the holes after drilling them out. alternatively, vice grips, C clamps or just a floor jack holding up a patch is important--- you want your patch overlap TIGHT against the original metal.


I cannot overstate the "do not try to seam weld" thing enough, especially when you are just starting off. It will just frustrate you and burn through a lot of metal and a lot of grinding wheels  (tip: Flap discs are better for grinding DOWN --[not OFF]-- welds... and wire wheels are better for cleaning off metal than grinding wheels so you don't make the receiving metal too thin to take a weld). Seam welding is for thicker metal, not for the inexperienced welder on body sheet metal. short 1" stitches, ok. But not a full seam unless you want to see what an oilcanned panel looks like.


Good luck and have fun. Wear long sleeves, wear a mask, consider wearing protective earmuffs (weld splatter in the ear canal while lying on your side SUCKS), and wear leather shoes-- tennis shoes with mesh uppers will get weld splatter balls through them and down between your toes-- that SUCKS too. I do not like the thick ass welding gloves preferring just leather tig welding style gloves, but I have a high pain tolerance for short periods. (But they are loose enough to be able to shake off FAST) Have a small bucket of water nearby with an old washcloth or towel in it to douse hot metal / undercoating fires/burning clothing quickly.

 Posted: Jan 24, 2022 05:59AM
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CA
Good synopsis Markiss!

To add to response #2 and the issue of bare metal rusting quickly, I suggest using weld-through primer on metal you clean off. You can get it in rattle cans and keep it handy for use after each session. You can also use it on the patch material back side so it is protected where the old and new metal overlap.

When applying a patch, tack it in place and gradually fill in between the tacks with more tacks, allowing the patch to cool and settle back to shape. Once the tacks are close enough, you can run a bead between them.

I had to replace a section of outer sill (rocker panel) and didn't have a welder. I cleaned up the edges of the cut out "hole"  and applied weld-through primer to the bare metal. Then I fitted carefully the new sill section ( also weld-through primed) and pop-riveted it into place. Then I took the car to a friend's body shop to have the seams welded. The I removed the pop rivets and filled the holes. All done!

.

"Hang on a minute lads....I've got a great idea."

 Posted: Jan 23, 2022 03:26PM
 Edited:  Jan 23, 2022 03:42PM
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None of what you said sounds stupid to me. It's all part of learning. 

I pried out the sound deadening on my Mini as well. Just need stiff putty knife, a heat gun, and patience. It takes a bit to do it all. But do it outside, or have ventilation indoors. You'll get a little headachey after a little bit from the fumes that it releases. 

I'm not a pro bodyman or welder. Can't speak too much from personal experience but can speak to some of your questions.

For your #1 question: If your doing your own patch work instead of buying replacement panels, I'd go with the same gauge/thickness of metal. So that way there's not variations and lips/edges from two different gauges of metal meeting each other. If you go the route of replacement panels, they don't fit like a glove. The Heritage version seem to fit better. They came from original stampings. There's other aftermarket version that need a bunch more 'persuasion' to fit. Either cutting, reshaping the panel, or adding metal. 

2. - After metal is exposed it will slowly start to rust. This will occur quicker in more humid climates. It will be just surface oxidization rust which is easy to sand off. Don't want to do too much grinding, as it will bring down the thickness of metal causing it to warp easier and cause waves in the metal. The metal on Minis isn't so thick to begin with. Some waves and low points will be levelled out once you apply bondo over it all afterwards, once you're done your bodywork.
As for primer, there's all sorts of autobody/metal primers out there. But before applying that, make sure the metal is clean, clear of debris and dry. Once you start exposing metal, make sure to have enough time to carry on with it. Wouldn't leave it for weeks and months because of other stuff coming up. You'll maybe then have to resand and clean the metal again before priming. 

3. - Pretty much the process in general.
If you are overhauling the whole car, and have access to a media blaster, know someone that does or have a budget to someone blast the entire car, I'd recommend that approach. There's usually a lot of rust on Mini's. I never thought my Mini was as bad until I started with a few processes. Some was obvious with the bubbling, holes, etc. But some other areas were uncovered, and were bad where I never knew they would be. I had a lot of hidden patching done by a previous owner that used bondo and wire mesh to patch over rust holes, and then painted over it. It would suck to do a whole bunch of patch work and then find that you need to replace that panel anyways, or have more to do. With a totally blasted car, it's then easy to see how good or bad the car is, and what can be patched or replaced. If going this route, use a medium(material) that is not too abrasive. Sand would be too abrasive. Try soda blasting, or maybe crushed glass. Anything too abrasive causes warping and heating of metal. You wouldn't necessarily have to blast the whole car. Maybe could get away with the lower half. 

4. - Welding does take a bit of practice. If you're going to take the bull by the horns and do it yourself, get some scrap metal and try to weld that stuff first before trying on your car. Some metals don't weld to each other as well. You cannot weld things like aluminium to steel (or vice versa) for example. Aluminum welding takes a different touch. You will need supplies to weld. A welder (an average new one can cost around $500 and go way up from there) rods, accessories, safety gear like gloves, eye protection/mask, etc. Those cost money. Weigh it out. If you think you'll use this stuff again, then it may be a worth-while investment. If you don't think so, it may not. Borrowing would be best then. Or asking a friend to use his and help with some tips, for a case of beer. Or, just hire someone. If you're lucky enough to have just one small area or just a couple areas needing cutting and welding, it would not be cost affective to buy all the gear. 

.
Simple recipe for Excitement:  Take 1 Classic Mini. Throw in 1590cc's of engine. Add 5 gears. A dash of 94 octane. A sprinkle of style inside and out. Toss in 1 MadMan and finally heat tires and pavement to taste. Recipe produces 1 Mini VTEC conversion and full satisfaction. Motor on!
 Posted: Jan 23, 2022 12:43PM
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Soon enough I am going to be pulling all of the sound deadening and carpet out of the mini so I can properly see the rust spots around the car and I have a couple of questions. Keep in mind that I am completely ignorant to welding so these may be a dumb questions

1. Is there a specific kind of sheet metal I need to buy to replace spots I cut out?

  1. 2. Once I cut out and weld new metal in what kind of paints/primers are recommended to keep the problem from happening again?

  2. 3. What kind of process do you normally take when you have rust? is it as simple as cut out bad spot, grind away to bare metal around spot, weld new metal in place, grind away welds, and paint?

  3. 4. What kind of welder is recommended for someone who has never done it and should I just hire someone to do it instead of trying to borrow a welder?

  4. 5 .What tips do you have for a noobie who has never done body work before or welding at all?
 
Thank you so much for any tips and I'm sorry ahead of times if these seem stupid!