Fabricating panels and performing patch repairs on car bodywork involves several steps, from preparing the damaged area to shaping and welding the new panel. Below is a general procedure for both fabricating and repairing car bodywork:
### Tools and Materials Needed:
- **Body hammer and dolly set**
- **Metal shears or cutoff wheel**
- **Angle grinder with flap disc**
- **MIG welder**
- **Sheet metal (typically 18-20 gauge steel)**
- **Marker and measuring tools**
- **Clamps and magnets**
- **Cutting tools (plasma cutter or angle grinder)**
- **Wire brush or stripping disc**
- **Protective equipment** (gloves, welding mask, safety goggles)
- **Filler (such as body filler or fiberglass resin)**
- **Sandpaper (80 to 400 grit)**
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### 1. **Inspection and Damage Assessment**
- Inspect the damaged area to determine the extent of the damage.
- Decide if a full panel replacement is necessary or if a smaller patch repair will suffice.
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### 2. **Prepare the Damaged Area**
- **Clean the Surface:** Remove rust, paint, or dirt from around the damaged area using a wire brush or stripping disc.
- **Mark the Damaged Area:** Use a marker to outline the area to be cut. Ensure you account for any overlap if fabricating a new patch.
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### 3. **Cut Out the Damaged Metal**
- Use an angle grinder, cutoff wheel, or plasma cutter to cut out the rusted or damaged metal. Be sure to cut slightly beyond the damaged area to ensure all weakened metal is removed.
- Use clean, smooth cuts and avoid jagged edges.
- Once the metal is cut, use a grinder to smooth out any rough edges.
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### 4. **Create the Replacement Panel or Patch**
- **Measure the Cut Area:** Measure the size of the area removed and transfer the dimensions onto the sheet metal.
- **Cut the Patch Panel:** Using metal shears, cut out the new patch or panel from the sheet metal. Make sure the new panel is slightly larger to allow for trimming or welding.
- **Shape the Panel:** If needed, use a body hammer and dolly to shape the new panel to match the contours of the car. This is particularly important for curved sections of bodywork.
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### 5. **Fit and Tack the New Patch**
- **Test Fit the Patch:** Position the new patch into place and ensure it fits snugly with the surrounding metal. Trim if necessary for a perfect fit.
- **Clamp in Place:** Use clamps or magnets to hold the patch in place, ensuring it's flush with the surrounding bodywork.
- **Tack Weld:** Start by tack welding the patch to the surrounding metal in several spots. This will help prevent warping from heat during welding.
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### 6. **Welding the Patch or Panel**
- **Stitch Weld:** Use a MIG welder to stitch weld the patch or panel in small increments to avoid overheating or warping the metal. Alternate between different areas to distribute the heat evenly.
- **Grind Down Welds:** Once the patch is fully welded, use an angle grinder to smooth out the welds until they are flush with the bodywork.
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### 7. **Body Filler Application (Optional)**
- **Apply Filler:** If necessary, apply body filler over the welded area to smooth any imperfections. Spread it evenly and allow it to dry according to the manufacturer’s instructions.
- **Sand the Filler:** Use 80-grit sandpaper to rough-shape the filler, then move to finer grits (180, 320, etc.) to achieve a smooth finish. Use a block sander for an even surface.
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### 8. **Final Sanding and Finishing**
- **Smooth the Entire Repair Area:** Once the body filler or welds are smooth, use 320 to 400-grit sandpaper to smooth the surrounding paint and blend the patch repair into the rest of the bodywork.
- **Clean the Area:** Wipe down the area to remove any dust or debris, and prepare it for priming and painting.
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### 9. **Prime and Paint**
- **Apply Primer:** Use an automotive-grade primer to cover the repaired area. Allow it to dry completely, then sand lightly with fine-grit sandpaper (400 grit) to ensure smoothness.
- **Apply Paint:** Once the primer is smooth, apply basecoat paint followed by clear coat. Blend the paint with the existing finish and allow it to cure.
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### 10. **Polishing and Finishing**
- After the paint has fully cured, polish and buff the surface to blend the repaired area with the surrounding panel for a seamless finish.
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### Tips:
- **Avoid Heat Warping:** Keep your welds spaced and cool to avoid heat warping the thin sheet metal.
- **Test Fit Multiple Times:** Constantly test the fit of your patch or fabricated panel to ensure alignment with the bodywork.
- **Work in a Well-Ventilated Area:** Ensure proper ventilation and use safety gear when welding or using chemicals.
This process ensures a professional-quality patch repair or panel fabrication that restores the integrity and appearance of the car bodywork.
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