Monday, February 10, 2014

Dent Repair & Metal Finishing on Left Rear Quarter

With the snowiest winter in decades demanding more time than it deserves (thank the Lord for a new snow blower!), a week of time spent out of the country for work, and a shop heater misbehaving, I was getting a bit anxious to spend proper time in the shop dedicated to the Boss since my last update.  However, though I have been delinquent in keeping up with fresh entries for a few weeks, I have managed to make good progress.

To begin, the task of repairing 44 years’ worth of accumulated dents and dings in the left rear quarter had finally come on the menu.  Having managed to clean and preserve the bare metal panel successfully, the time to sit down to the careful and particularly delicate work of dent removal and metal finishing was at hand.

After several hours of careful study of every inch of the panel, I decided it best to start at the front and top half of the quarter and methodically work my way to the back, repairing every irregularity in a given area before moving on to the front lower half and repeating the process.  This method allowed me to maintain a clear focus on each repair area until the repairs were as good as I could possibly make them.
Beginning in the area just behind the striker post, I had a nice, sharp dent that slightly deformed the leading edge and radiated back into the open panel by several inches.  Like with any proper metal work, some form of “indicator” is required to understand and visualize the extent of the damaged area so you know exactly what needs to be repaired and how far out from the heaviest damage to begin the correction.  The first rule of dent removal is to understand that dents must be removed in the reverse order in which they were created.  In other words, the outer peripheral damage must be slowly moved back into shape first if you are to get the “core” damage to move as well.  In simplest terms, if the dent started at the front and ended at the back, the repair of that dent starts at the back and moves to the front.

My preferred “indicator” on bare metal is a giant Sharpie marker instead of conventional guide coat paint.  It dries quicker, is much thinner, very easy to clean up and does a nice job of highlighting the low spots.  Oh, and it’s ridiculously cheap too!  So, the first order of business is to swab the entire repair area with Sharpie and lightly scuff the surface with a rigid sanding block with 80 grit paper.  Very quickly, the true extent of the dent is revealed and the road map for repair is defined.
Starting at the outer edge of the dent, began the repair by welding a series of draw pins about ½” inboard of the edge of the dent and began the careful process of pulling the metal while gently tapping the outer crown with a dinging spoon.  Then I cut the pins off and ground the heads smooth and inked the area.  After the ink dried, I lightly sanded the surface again with the rigid sanding block to check progress and define what area would need attention next.  This basic process was iterated about a dozen times over several hours to bring the surface as close to the original contour as possible.  Once complete, all that remained were two small shallow points where I had to shrink the metal with heat to pull the leading edge back into form and a few shadow outlines where the welded draw pins were removed.  All told, the final skim of filler that would be required will be less that about .020”.

Moving back on the quarter to the trailing fender lip radius, I had to attend to a dent that was an alarmingly similar to the first one.  Fortunately, the damage was not as severe or deep, so less time was required to get the metal to return to its original position.  Using the same technique as previously described, this dent was pulled and the fender lip radius restored such that almost no filler will be required at all.
The final metal finishing task on this quarter panel involved straightening up the area where the marker light was filled with a welded patch as an aesthetic improvement.  Since this would involve a much larger area that would require attention, I marked out the zone with a marker to help keep my mind focused on the specific repair area.  Then I coated the area with machinist dye as an indicator similar to the Sharpie marker I used earlier.  Machinist dye is easier to apply over a large area than Shaprie marker, so I use it for the sake of convenience.  Another advantage to it is that it stays wet longer and allows you to look at the panel from various angles with a high gloss on the surface to see in great detail very subtle (and not-so-subtle) irregularities in the metal that will require attention.

Again, the repair area was sanded to provide the appropriate contrast and I went to work with more conventional hammers and dollies, dinging spoons, bulls eye picks, a large shrinking disc and rubber mallets to nudge the surfaces as close as possible to the original contour.  No welded draw pins were required in this critical area.  Unfortunately, I failed to properly document this operation but I am happy to report that this are too will require very little filler to get straight.
The final area of concern was the front lower joint between the quarter and the rocker.  This area required extensive repair for rust and other damage and I welded the seam and ground it smooth for aesthetics.  Careful metal work during the reconstructive phase allowed that no heavy dent repair was required in this area as the areas that I wanted to be low (e.g. weld seams) were already in shape and the rest of the contours were very close to what they were originally.  So after a few minutes with a dinging spoon and dolly, the area was ready for filler.

With that, the “heavy” metal work on the left rear quarter was complete and it was time to plan the process of applying fillers and smoothing up the panel and the associated seams before sealing everything up with primer.

Using a huge Sharpie marker, I coat the entire damaged area and use it as a guide coat to see just where I need to work.  The camera flash already makes the dent very obvious.

Lightly sanding over the inked area very clearly shows the extent of the repair area.  As you can see in this shot, the low spot carries out into the panel quite a bit farther than can be detected with the naked eye.  However, with this technique, our work area is cleanly defined.

Beginning about 1/2" from the outer edge of the dent, I weld draw pins to the surface and begin the gentle pull-and-tap technique to ease the metal back into its original shape.  This is an iterative process that requires patience and a clear understanding that the dent must be removed in the reverse order that it was created.  In this case, the initial impact point is at the far left edge of the dent.  That is why the repair is started from the far right side as it was the "last" area to be damaged in this singular impact.

After about three hours and 32 draw pins later, the metal is almost perfectly returned to it's original form.  The two dark spots on the left edge are the result of some very localized heat-shrinking I needed to do to get the door opening edge to come back to shape.  This was done with a special tip on the stud welder gun that pinpoints the heat in a very small area and minimizes distortion in the material.  These small marks are actually very shallow, but filled with ink, so they look very pronounced in the shot.

A handful of draw pins and one less dent!

Even sky lighting the repair area shows very little filler will be required to get this area perfectly smooth.  Now to repeat this repair procedure for all of the other areas on this quarter!

My photo-documentation skills really suffered on this blog update, but the sanded area in this shot was once the location of another nasty little dent that deformed the wheel arch.  Using the identical techniques described above to remove the first dent, this area will require virtually no filler as well.

A larger and more challenging area to straighten is the rear quarter section where the original marker light hole was welded up.  To enable me to more clearly focus on the area, I outline the full extent of the work surface with a marker as seen here.

Since the repair area is much larger, I use sprayable machinist dye to coat the surface as my guide coat.  While it is wet and glossy, I can easily spot areas that will need work.  This is something I do quite regularly and often use simple wax and grease remover sprayed on the panel to check my progress and visualize the surface in final finish.  Works great!
After several hours of very gentle manipulation from both sides of the panel, the marker light area is quite straight and ready for filler.
 
The last area I needed to evaluate was the lower front joint area where the quarter and rocker join.  I welded this seam up for aesthetic purposes and repairs were required to the rocker and wheel arch area as part of the rust repair procedures.  Fortunately, the repair techniques I used allowed the welds to be slightly below the original surfaces and only slight correction to the surfaces were required before moving on.

11 comments:

  1. Very nice work Sven. You are indeed an artist. I wish I had been able to employ half your skills on my own build.

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  2. Thank you very much for your kindness Alex! I sure hope others see my work the same way as I am moving more and more toward pulling in "paying" jobs as I try to move out of the corporate frying pan!

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  3. Another rousing episode of Sven's Corner :) Sven, seriously, you should think about perhaps video taping some of these segments and posting them to You Tube. This would allow you to reach a larger audience and perhaps begin to build a following that would eventually use your services once you jump off the corporate cliff.

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  4. Much appreciated RJ! I have been asked on several occasions to produce more “how-to” video tips but I have no idea what equipment would be required to produce good quality videos. I am sure my Go Pro camera is not the right camera for this type of work, and I hate poor quality video and sound on this type of topic. As such, I have just let that topic remain dormant until smarter people than me can show me the way! I am wide open to an education on this front for sure!

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    1. Sven, like your mechanical skills, I think this video thing should develop the same way. Start with your Go-Pro camera - don't worry about sound and quality for now. Worry about where the camera needs to be, listen to your voice - 'Am I boring? - am I interesting? - I need more clarity there - I need less explanation and more showing'. Show them to friends...or us...we are your best audience. We'll throw lots of rocks if you need them thrown :) You didn't start out with a giant tool box of cool tools - you started out with 2nds from your Dad and the classic $109 Sunday flyer special from Craftsman. Learn the craft of videoing, then worry about the equipment. I actually get more enjoyment out of watching shows like Fast and Loud for their technical video taping than their content. It's fun to watch the new shows grow their own style. Give it a go - we are here to help!

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    2. Very good analogy RJ. I get it! I might have to just roll over and give it a try. I am NOT what you'd pick as the "face" of a well done video production, but there are ways around that.

      I did a few time lapse videos and stuck them up on YouTube for entertainment and to see if I could do it. I find this sort of thing a lot more work than blog updates, so it might be a while!

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  5. Wow. Was this Deja Vu for me. You will have very little filler on the quarters. High build primer may be enough. The advantage you had is your dents were small. My ginormus "cow running into the side of the quarter" was much more involved, not to mention the rust. I still may end up going back and doing more work to make it flatter. Excellent work, as usual.

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    1. Ha! I was thinking about your trials on your 68 the whole time I was writing this latest update Dennis! I just KNEW it would strike a chord with ya!

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  6. Great work on the small details Sven! That car is going to be flawless when you get finished.

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    1. Grant, you are too kind! I am certainly going to give it every effort to make it as good as I can and so far, I am happy with the direction it's headed. Loooooong way to go!

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  7. Wow, I had no idea the dent repair process was so extensive. Nice work! That car is looking great!

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