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Patch Panels by Jim Clark, The Hot Rod M.D.

Repairing rusted panel damage or installing panels like gas filler doors can create a lot of panel distortion and necessitate a lot of additional finish body work when the seams between the panels are butt-welded together. A flanged panel that overlaps where it is welded creates a double-thickness of material and a seam with little distortion or vulnerability to water penetration. Most patch panels that are purchased have a flange on them so that they can be joined securely at the weld point without a lot of heat distortion.

However, when working with sheetmetal modifications or raw sheetmetal panels you have to create your own flanged joints or work with butt-welded seams.

Air powered flangers are available and they create a nice clean finished flange on sheetmetal panels. A good investment for a shop that is doing this kind of work on a regular basis. For the do-it yourself rod builder having all of these trick tools can be more than the budget can stand though. A more affordable alternative is a special purpose hand tool like the panel flangers (item#31092 & item#31090-extra wide for up to 18 gauge metal) offered by The Eastwood Company.

They have special jaws in vise grip pliers that create a flange in small increments. The process creates a professional type flange that provides tight distortion-free joints where the panels are welded together. They create a .040 offset flange for clean welding with a limited amount of grinding. Both models retail for about $29.95. We used one to create the flanges while installing a gas filler door. The process is shown in the accompanying photos            

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When joining two pieces of sheetmetal a lap joint creates a much stronger joint and one with less chance of warping or distortion from the heat created from the welding process than a butt-joint. The jaws on this Vise Grip panel flanger from Eastwood Company (item#31092 & item#31090-extra wide for up to 18 gauge metal) create a flange along the edge of a sheetmetal panel providing an overlapping joint between the panels


Shown is the profile of the jaws of the panel flanger. Gap where the jaws offset allows for the step in the panel created when the jaws close over the metal panel.













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The flange is formed by repeated crimps along the edge of the panel moving the width of the jaws with each crimp


The flange can be the full width of the rear recess in the jaws or shorter where space available limits the width of the flange overlap. The right edge of this filler door panel almost butts up against the joint in the adjoining panel necessitating this narrow flange














Flange offsets to the rear with the tool in this position. Turning the tool over 180° will create a raised flange or allow the flange to be created from behind the panel when access is limited from the face side of the panel


  We chose to add a gas filler door to the side of the van for a rear mounted auxiliary gas tank. A filler door was cut from the side of a van at a wrecking yard and the dimensions transferred to the side of this van. The filler for the side tank was used too align this one at the same height as that one
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We cut the gas filler door panel to size and flanged it before marking the actual cutout in the side of the van. The side of the van could be cut out and the flange made in that panel but it is much easier to work with the piece that will be welded in  

An air powered cutoff wheel makes a cleaner cut than trying to saw or cut the panel with tin snips. Another method for cutting into the side of a vehicle is an air powered nipper or shear. They take out a narrow strip of metal and require clear access behind the panel, which can cause some problems when braces or overlap occurs behind the cut. The guard would normally be in place on the cutoff tool but was left off to show the process more clearly in the photo


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Here is the hole cut and the paint removed prior to clamping the panel in place and welding. Panel is lying flat behind the opening and will install against the backside of the opening therefore the inside also has to have the paint removed  

Panel ready for installation. All four sides have been flanged and paint removed. Three sides have a full flange with a smaller one on the right to allow for the panel seam at the corner of the van where this is being installed


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We welded the panels with a MIG welder doing short sections at a time and moving to different points around the panel as we proceeded to prevent heat distortion. The flange was clamped where we were welding to prevent any gap between the panels that are being welded. A stick (arc welder) or acetylene gas welder can be used but both tend to create more panel distortion due to the heat and also create more spatter. TIG welding creates an excellent joint but the equipment can be very expensive and out of the budget for many do-it yourself hot rod builders.



The finished panel is welded in place without any distortion due to excess heat. The welds have been ground flush with the panel and will be smoothed with body filler after the inner housing has been installed

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Weld seam is easier to see in this photo. Narrow flange on the right was necessary because of the close fit at the intersection of the rear corner panel.  

Backside of the panel shows how they overlap making a much more secure watertight connection. Double thickness of the panel’s flanges created a flush welded seam and smooth transition between the panels on the outside surface. No ragged weld seam on the inside.























































































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