During a restoration or a custom build, you may need to replicate a part from scratch by making a pattern of the original. In the case of Project Sunny, the Range Rover we’re restoring, we came across some brackets that couldn’t be saved. One was a rear fender mounting bracket with a fuel tank vent hose carrier that didn’t survive the blast cabinet. The other one holds an evaporative emissions canister and was destroyed trying to remove its seized retaining bolt.
Neither is available as a new replacement part, and any used part would have likely been in similarly poor condition. But one of the things we’ve come to discover during this project is just how simply these vehicles were constructed. Both these parts could be easily fabricated from sheet steel using basic metal fab tools, so we got to work.
For this article, we’ll focus only on making an accurate replacement for the fender mounting bracket. We’ll walk through the patterning and layout process plus the steps and tools needed to make the new part. You can use these same basic principles to replicate just about any other sheet metal part.
Measure the Original
To make a reliable replacement part, you need to pull measurements from a reliable reference. While our bracket wasn’t in good enough shape to refinish, it was decent enough to get critical dimensions.
We started by figuring out how thick the original sheet metal was. Between the corrosion on the part and the effects of media blasting, a good measurement was hard to get. The thickest areas where hardware had been measured out to 16-gauge using our sheet metal gauge. In some spots the thickness had been reduced to 20-gauge or lighter.
Next, we gathered all the critical dimensions on the part. This piece is most flat with two small flanges for rigidity, plus a pair of angled mounting tabs. It also contains a pair of slotted ¼-inch holes in each tab, plus a two ¼-inch holes on the main flat. The two slots and one of the holes fall on the center line of this symmetrical part. The other hole was slightly offset from the center line.
A steel ruler and dial caliper were all we needed to gather accurate dimensions for the drawing. The overall width measured out to 2 inches, while the overall length was just over 11 inches. A rough sketch of the part allowed us to record all our dimensions which we’d later transfer to drawing.
Make a Plan
From the sketch and dimensions, we then laid out a plan. This could be done in a CAD program like Solidworks or a design tool like Photoshop. However, we just did it on paper for simplicity because the design isn’t that complicated.
We started by drawing out the overall dimensions and the center line. From here we referenced the other dimensions to mark out centers for the holes, the bending lines, and any trimming. At this stage, making as many notes as possible on the drawing is helpful. It’s easy to forget numbers and other details once you’re working on the new part. Make sure you’re technical drawing is as thorough as possible.
Transfer the Design
We found a remnant piece of 16-gauge steel 12 inches wide and laid out our blank using the overall dimensions. We first marked the material with a wide Sharpie® marker. This allowed us to better see the layout lines marked by the metal scribe from our sheet metal layout kit.
We chose to cut our blank panel first, using a 4-foot stomp sheer before laying out the rest. This way if we accidentally cut it wrong, at least we hadn’t wasted time doing layout on a bad blank.
Once we had a good blank (first attempt, thankfully) we proceeded with layout out the rest of the reference marks. This meant a center line for the main part, plus trim lines, bend lines, and drilling marks. Before moving on, we laid the blank up next to the original part for comparison.
Trim the Blank
Because this part required us to drill holes, we took care of those first. It’s far easier to do this while the piece is flat than after it’s bent. The slotted holes will be opened up later.
Our piece also narrowed down by almost an inch for the tabs on the end. To trim these strips off, we used the throatless shear, aligning the cutting edge with the cut lines. We then dressed the edges on a belt sander to remove any burrs from the drilling and hand-cutting procedures.
Bend the Part
Our piece required bending edges in two different planes. The longer edges each required a ¼-inch flange, while the end tabs were bent in opposite directions from each other. The small flanges had to be bent first. We used our vise-mounted 20-inch benchtop brake to from these bends.
For the end tabs, we used a large bench vise with the jaws aligned on the bending mark. We bent these tabs to match angle of the original part, verifying accuracy by eyeball. From here, the part was basically done. All that was left was to open up the slotted openings between the drilled holes using a small cutting disc.
Words of Advice
Patterning a new part based on a compromised original takes patience and a degree of critical thinking. It helps to understand the nature of the part, for instance. In our case, it wasn’t a ‘precision’ part with tight dimensional tolerances. Knowing this meant we were able to bend the end tabs by eyeball, as an example. Also, this wasn’t a load-bearing part, so we could have used 18-gauge material if we hadn’t had 16-gauge on hand.
Ultimately, you determine your own degree of precision and detail on a project like this. Regardless of how you proceed, we offer the following recommendations:
- Assume nothing, confirm everything
- Measure twice (or more), cut once
- Make a test piece if you’re not sure
- Relax, it’s only a piece of metal until you make it a part
