Building Fiberglass Fenders: Part III

With the recent application of bondo leveled and cured, I can now smooth out the surface of my fender – again. As it turned out, the two outer thirds of the circumference of my fender were about the same height. The middle section was about ¼ to 1/3 inch on the shallow side. It is in this center section that I need to reshape the fender around my newly formed ridge of bondo. I accomplish this with more bondo and a credit card that I use as a spreader. I like using credit cards or other thin pieces of plastic as spreaders because they can be used to produce a flat smooth surface or a nice smooth curved surface.

After the surface of the plug has been re-shaped with bondo I go through a short series of filling and sanding until the surface is smooth and ready for a quick coat of primer. The primer helps me spot any defects in the surface. I like using primer because it dries quick and I can bondo right over it to fill defects if necessary. As it turns out, my new plug surface is nice – nearly perfect.

The next step in this project is to apply 2 or 3 more coats of primer. After the primer dries completely, I sand the surface smooth with 400 grit wet sand paper. This really smooths out the surface of my plug and gets me closer to molding.

With the plug at this stage, I have to trim it and then remove it from the foam and rim. To trim this plug, I have decided to use my Dremel tool and the piece of stock aluminum that I used to smooth the surface of the plug. The first thing that I do is attach the aluminum piece to the hub with the retaining nut. I run the nut tight but not so tight as to hamper smooth movement of the aluminum. I then decide how far I want the fender to wrap around the tire on my finished product. I mark that line around the length of the fender plug with a pencil being sure to mark that spot on my aluminum guide so that I get the same depth on the other side of the fender plug.

With my lines marked, I attach my carbon – fiber cutting wheel to my Dremel tool and then attach my Dremel tool to the aluminum guide with masking tape. Before I begin cutting, I sweep the tool around the length of the fender to make sure that the aluminum guide is going to keep the cutting tool on course. Since it does just that, I start the tool and begin trimming the edges of the plug.

The tool and the guide work perfect. When finished with the one side I flip everything to the other side and trim there as well. Now I remove the foam from the inside of the plug and begin to think about how I will mount this plug to a board for the molding process.

So far – so good!

Happy Glassing


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