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Tin bashing

Discussion in 'Paint and Body' started by david85, Jan 11, 2015.

  1. david85

    david85 Full Access Member

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    I came across a decent set of sheet metal a while back. Nothing is perfect but its about as good as they come for my part of the world short of going aftermarket. The fenders were in great shape but not perfect...and I'm fussy. One had a few pinholes at the front lower corner, while both had pitting between lower rear joint. In reality the sheet metal was still solid but all things considered, it was easier to simply replace the infected areas.

    Its a real eye opener when you see what gets caught in these pinch points. In order to repair it properly, I had to cut off the lower root of the inner fender wall. What you see here was AFTER power washing the fender. Also note the stock sheet behind the inner wall to protect against the zip blade going through the outer skin.
     

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    Last edited: Jan 11, 2015
  2. david85

    david85 Full Access Member

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    I generally don't take many measurements when doing stuff like this. Adjust, bend, trim, test, repeat. Once I got the shape where I wanted it, I scribed the contour of the fender and trimmed it again.
     

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  3. david85

    david85 Full Access Member

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    I lined up the edge of the patch to be just inside of the bottom corner. This helps control warping and makes it easier to clean up the weld. Again, I scribed a mark to know where to put the cut for the fender sheet so both panels match each other as closely as possible. The result is a nice tight fit. Its not visible here, but the edges were also cleaned up with a metal file to get them as square as possible. A taper is not needed here and would only increase the chance of a blow through when welding. Also, since the patch material is 16ga galvanized, the edges have to be bared to get the zinc off. It can be done without cleaning, but it just works better with the tig welder (yes, TIG!) when the steel is raw.
     

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  4. david85

    david85 Full Access Member

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    I first tried tig welding on thin sheet when I was rebuilding the cab corners on my F150. I was strongly advised against it because its easy to put more heat into the sheet compared to wire feed, which can be done with one brief shot. In practice I found that blend welding actually put less heat into the metal, and also allowed for an extremely clean, low profile joint. The trick is to have a zero gap joint with square edges. If they can be held together perfectly tight, it works beautifully. What I did here is still similar to how anyone would use a wire feed (MIG) in that tacks are carefully placed wide apart, then drawn closer together to control warping and keep everything as tight as possible. The difference here is that NO MATERIAL is fed into the parent metal.

    What I did here is strictly a blend weld. I can do this by striking the arc on the thick patch side of the joint, and carefully weaving across side to side. Getting a tack started can be tricky since its easy to open a hole if the two puddles fail to join. If a hole opens, there is no choice but to add filler to close it off again. This is where it can get messy due to much more heat and material (and shrinkage). I put a measuring tape next to the tacks so you can get an idea of just how small the weld really is.

    The advantage is a weld that is so clean and flush, you can almost smooth it over with a file. I barely had to touch this with a grinding wheel before hitting it with an abrasive polishing pad. This probably wont require any filler, but I may sill use a high build primer when it comes to finishing.
     

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  5. david85

    david85 Full Access Member

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    The inside of the weld was washed over in one pass as a precaution to eliminate any locations where penetration was not perfectly 100%. Normally this isn't needed, but I intentionally went a little cold on the outside pass to avoid blow through.

    Here is the end result after 3 hours from the first cut. The inside of the inner fender will get welded back on eventually. Once the inner and outer panels are spot welded back together at the lower seam, I'll use a zinc rich primer to fill the space between the two sheets (immersion in a shallow pan). I'd still like to devise a way to prevent all that sand from collecting in there but I'll have to think about it some more. In any case, this will be getting some under coating poured in on top of the primer, THEN some thick oil on top of that.:backoff

    3 hours for a job like this is a pretty good reason why few shops still do this kind of work. The time alone is already more than an aftermarket fender. But this way I know what I have. Besides, these are OEM fenders;Sweet

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    Last edited: Jan 11, 2015
    Kiwif150 likes this.
  6. david85

    david85 Full Access Member

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    Here is the repair for the front lower corner. I got a little ahead of my self and failed to take photos during the the job, but you can still get the idea of what was involved. Again, this will be heavily covered in whatever rust proofing I can get my hands on after they are painted. The plan is to paint the hood, doors, fenders, valance and cowling painted separately, then drop them on after. That way everything will get covered, even the hidden areas. I'm still mulling over whether or not to have rock guard put on when they get painted. For now the plan is to have a professional painter do the actual paint. None of the shops in town were interested in doing any more then that on an old beater like mine.:rolleyes:
     

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  7. david85

    david85 Full Access Member

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    Well that's all the photos for now. It will probably be another 2.5 weeks before I can get back to this. The doors and hood won't require any invasive surgery, so hopefully all these loose parts can get painted fairly soon. My goal is to have the truck done for a summer of road trips. We'll see if I can pull that off...
     
  8. 79jasper

    79jasper Chickenhawk

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    Autogenous welding.
    Imagine if you had a foot pedal.
    Looking good.

    Sent from my SM-T537R4 using Tapatalk
     
  9. tbrumm

    tbrumm Full Access Member

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    Nice job and thanks very much for the pictorial! Wish I had the tools and skills to do nice body repair work like this!
     
  10. lotzagoodstuff

    lotzagoodstuff Supporting Member Supporting Member

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    Very nice work ;Sweet

    Just a question: have you thought about POR or maybe the Loctite Extend product on the back sides and/or pinch weld areas where stuff collects? I am currently back in the rust belt and I forgot how stuff rusts here.

    Good write up, nice pics and seriously nice fabricating/welding ;Sweet
     
  11. IDIoit

    IDIoit MachinistFabricator Supporting Member

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    another advantage TIG has over MIG is that with MIG, you have the chance of pin holes. altho this is a lower part of the fender, if it was any part of the cab, you would have to seam seal or duraglass to seal it.
    great job! my linclon 275 has a foot pedal and with my lead foot i tend to warp the hell out of 12 gauge.
    i only use my tig for frames and thick metals where alot of penetration is a must.
     
  12. david85

    david85 Full Access Member

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    I've heard many things about POR but no first hand experience yet. I might try it here, or I might just break out the sand blasting gun to dig out the pitting. Main concern is how it would behave in close proximity to a weld. My understanding is that its a two step process.

    We have a miller dynasty 200 in our shop and it does have a foot pedal but I just got used to the thumb throttle. One less chord to trip on when doing this sort of work.
     
  13. icanfixall

    icanfixall Official GMM hand model

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    Really nice metal work but your weld should not look black. You are using too much heat. A foot peddle is a better way to control heat. A tig weld should look skinny. I worked for a few years welding stainless steel and inconel . When thats done correctly you have a yellow like rainbow in the weld. But black is too much heat. your burning the metal. What size weld rod are you using. You do have good metal working talent.
     
  14. dunk

    dunk Dunce

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    Looks good to me. When I did quarters on my '68 and cab corenrs on my pickup I did butt welds but with a mig. I'm no pro but it was passable. I prefer butt weld when practical because I see so many cars that have had quarters done and rott out where they were flanged, holds water. Butt weld and you can coat each side if you have access. Nothing I hate more than body work, so tedious. Hours upon hours to patch a small area.

    Good work man, can't pay a shop to do quality work anymore most just want quick in and out fender benders on newer cars where it's just bolt on new parts, skim mud, sand and paint.
     
  15. 79jasper

    79jasper Chickenhawk

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    Pretty sure he's using scratch start tig.
    On carbon steel (like car bodies) I have yet to see a Shiney finish.
    Definitely nothing like stainless.
    He's not using filler. He's getting a real tight fit up, and just melting the two together.
    More amps, faster travel, and more gas flow would make it look cleaner, but he seems to be doing just fine, imo.

    Sent from my SM-T537R4 using Tapatalk
     

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