It became thinner gradually over the years. The pick and file method can be used on any thickness of metal. I use the method on a regular basis. A person can cause grief if they thin the metal with excessive filing. Hammer and dolly the highs down rather than file off the high.
Mostly use the file to just highlite the highs/lows. Not to remove material, very little, if necessary.
The last pick in file that I did was in 19 74 on some 40 LaSalle fenders. I did go a little too far on one of them. The lesson I remember is don't pick can file with sneakers on all the filings wind up in your socks and sneakers. Thanks for the replies
Metal finish work is still alive and well, it just isn't common place in production body shops. You don't have to go far on the Net or even here on the H.A.M.B. to find good examples of it. If you think you knew at one time how to do it, take a refresher course and get back to it.
Out of shear frustration and being just about ready to beat the shit out of it with an 8lb sledgehammer,,,,with nothing left to loose,,,, I ran the shrinking disc on the back side /under side of the roof. I was amazed that it worked so well. Viewing it from the top side, these low spots weren’t raising. Viewing from the underside those top side lows were now underside highs and the disc shrunk those high spots. Unorthodox and maybe even wrong but it worked and took the metal from “wow that's fucked up” to “Looks like a few rounds of high build primer will finish it out” I’d like to get my metal finishing skill level up but I feel stuck. Seem getting the last 10% right takes 90% of the time and messing with it more makes it worse. I see before and after pictures of some amazing results and a lots of them. I don’t think I’ve ever seen a straight answer on how many hours it actually takes no matter how many times or who asks.
Some people are tempted to use a grinder in place of a file. The result can be very quick extreme thinning or grinding through. With extreme caution a grinder is useful in the process if for example to provide tooth for a thin coat of filler if that will be necessary. A sanding block wrapped with sand paper is a good file. A hand held flat fine grit grinding disc works well also.
Ya know 31vic, there's almost no answer to the time question that's right. Well one exception is my standard answer; "Less time than using bondo and making the shop look like a fuckin bakery." If anyone really wants to take something on try aluminum. 1st step, those old useless red sanding blocks? With the nails that hold the paper? That's a good dolly block for aluminum. A good hammer is a hard rubber version, and those small ones for closing paint cans are handy for that. The secret to aluminum is not to hit it too many times with a regular metal hammer, which means to be a little brave and hit it harder than your instinct tells you to. Anyone who's done hammer work knows EXACTLY what I mean because it also applies to steel. The shit you see in videos, the stuff that shows you where and how to hit, they're pretty accurate. Start in the center with a couple hits then go around the outside a little at a time, back to the center, around again. Like shampoo right? Lather, rinse, repeat. On bigger stuff you'll get it real close then get to the "...where I always fuck up..." point because it sorta stops moving back into shape. 1st pass with the file shows the lows and then it's time for the pick hammer. I have 2, a sharp one and a rounded one. I start with the rounded one and 'feel my way' toward how hard to tap it. Sometimes a dolly is good for support so the whole area doesn't rise and the blows focus the lows. As soon as you hear metal to metal STOP. Move to the next one, and so on, and so on. Back to your metal hammer, start shrinking those places some more, again with the center-around-around-center gig. As you feel good and confident about it, walk away. Yeah, walk away and get a sip of coffee, a smokey treat, whatever. All that hammer and dolly and pick work fucks up your hand's sense of feel. Seriously, it does. A few minutes to calm them down really helps, then when you go back you don't miss anything. Similar to the "fresh eyes" technique of having someone else look at a job. Another trick for feel, look away. Don't look at what you're feeling for and some may be amazed at how much more accurate you can be determining what's needed. Finding a high or low, stop and hold there, then look at it and mark it with a pencil. Do the same on all of it. Another helper for this stuff? Guide coat. Take a can of Krylon and mist a little bit on the area and board sand it. You'll end up with "Damn that's close..." or "Holy shit, this is a mess!" and either view is important. The sharp pick is what I usually reserve for the small stuff, smaller lows that ended up too hard to bump without stretching the whole repair area to shit. Blasting this info out might seem like this comes easy to me, but it doesn't. I have one difficulty with pick work, or maybe one sensation that gives me trouble. Being able to get those 1st picks right on target is my angst. I've learned to cheat a little and use a dolly as a finder to get me close. Once I'm there I can work all the way around the lows but it's easy for me to fuck up and miss, adding a high spot or pick mark I didn't want. Pisses me off every time it happens. Still, at the end of the day I'll take all the focus and challenge of metal finishing over slathering mud any day of the week and twice on Sunday. Even the frustration is more fun and rewarding than making a mess of bondo dust everywhere. I might visit this again with pics from the other computer. Oh, one last thing. It doesn't need to be black lacquer perfect. That's what primer/surfacer is for. Even a slight wipe of metal glaze is better than an 1/8" of mud but getting it to primer condition is enough and probably a real safe bet too. And yes, this can be done easily on most cars through the 70s, but once we get into new shit it takes a light touch. Or a replacement...
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