Article and Photos By: Will Ramsey – Faith Forgotten Choppers
Originally Published In The February 2020 Issue Of Cycle Source Magazine
When building a chopper, there is certainly something to be said for fabricating every single part in house from scratch. Such an approach allows the builder complete control of the design and showcases a very high level of skill; however, it also consumes a great deal of time. In some cases, skill level, finances, and time constraints may dictate modifying an existing part to reach the desired goal. In truth, customizing existing parts is really where this all started. From chopping frames to narrowing gas tanks, most builders find incredibly creative ways to manifest their vision of a custom chopper. Modifying existing parts, like a fender, can allow for an extremely accurate fit and a design feature that may be beyond the ability of the builder to completely build from scratch. This month we are going to narrow and existing front fender to mount onto a springer front end. By utilizing a mass-produced fender, we can achieve the desired look that our customer wants while still staying within his budget. Although I certainly prefer to fabricate from scratch. The cost and time invested to make a fender like this would simply not be affordable for this project.
After searching the catalogs with our customer, we decided that the profile of this fender would best fit the look he is going for. This fender is originally designed for a wide front wheel and measures 6 inches across, but we can narrow the fender to fit the narrow 21” wheel we have mounted on the customers bike.
Some basic measurements and design decisions dictates that our new fender needs to be 3 ¾ inches wide. This means we will be removing 2 ¼ inches from the center of the fender. That is a substantial amount and will greatly impact the look and geometry of this fender.
I prefer to use basic making tape to layout the cut lines on the fender. I always find it easier to pull long straight lines on compound shapes using tape rather than attempting to draw the line with a marker.
A simple 4.5” electric cut off wheel makes quick work of splitting the fender and removing the desired amount of metal from the center.
The cut edge of each half is deburred and cleaned prior to fitting the fender back together. Preparation is everything when it comes to a quality weld. Sheet metal is certainly not an area to cut corners on preparation; A cracked weld can quickly destroy a high dollar paint job.
Once fitted together, a series of tack welds will establish the relative alignment of the two halves. This step is extremely critical. The material must be meticulously aligned if you intend to metal finish the weld. Any overlapping or misalignment could temp the fabricator to grind the parent material down after welding. This would greatly compromise the strength of the weld joint and could certainly lead to a crack in the future. Take your time and don’t settle for anything shy of a perfect fit.
A quick planishing run in the hammer is used to qualify the weld seem just prior to welding. Again, it is this extra prep work that will make all the difference in your final product.
The weld seem must be properly cleaned both mechanically with a stainless steel wire brush, and chemically with a solvent like acetone. Any contamination left on the surface will simply form an inclusion within the weld bead. An inclusion will be a point of origin for weld failure.
Although back shielding a mild steel weld is not required, a full penetration weld on sheet metal does create a great deal of oxidation on the inside surface of the fender. I always use a backing tape method to catch argon and shield the inside of the weld. The result speaks for itself
Using the TIG method, the fender is welded. I prefer to use long continuous welds rather than skipping around. I certainly understand the theory that skipping around will reduce warpage. But in truth the warpage that occurs is simply a shrinking factor which is inherent to welding. This shrinking will be corrected in the hammer after welding. Skipping around does little more than offer multiple opportunities to increase oxidation and weld inclusions.
Planishing a weld after welding solve two very real issues. First, the stretching action of the planishing hammer will correct for weld shrinkage and qualify the surface of the fender. Second, the action of planish a weld essentially cold forms the material, which qualifies the grain structure, eliminating the stress riser common to welding sheet metal.
If your fit up and welding technique are flawless, you should be able to produce a weld that can be planished flat and require no grinding at all. A strong case can be made for leaving the material alone at this point to maintain maximum strength.
But in the age of social media everything has to look amazing. Most builders will choose to metal finish the weld. Again if the alignment was perfect, the weld technique flawless, and the planishing operation was carried out with attention to detail, you should be able to simply sand the definition of the weld bead out by hand with nothing more than some 220 grit sand paper and a block.
The final product should be something you are proud of and possess a unique look that will leave everyone questioning where did that fender come from… He must have made it himself. As always if you have any comments, questions, or concerns, please feel free to call the shop to talk to me directly. Thank you for your support! -Will