Tail Light Fabrication (4/5)

Previously, I was able to shape the metal frame a bit and stage a photo. The idea of bridging the gap between the back of seat and this frame with plastic did not work out. I didn't have the right material, tools, or number of hands required and a trial run went very poorly. I realized fiberglass might fit the bill.

I took a stab at fiberglass and learned a few important things.

• You have to have a mold.
• You have to make relief cuts around sharp edges and corners.

Without those things, you get this:

The absence of relief cuts was not obvious - I figured the cheap matting would be very flexible when soaked in resin. It is flexible, but it also still acts like a solid sheet and resists folds and bends. No matter what I tried, it would not stick down in the corners and some edges. As this cured, it resulted in large air bubbles.

I realized how valuable a mold would have been the moment I started. Nothing I did stayed in place. Everything began to droop and slide due to gravity. This resulted in a very inconsistent and ugly shape.

Furthermore, fighting these problems cost me valuable time because the clock was ticking on getting it set up while it was still workable. Other small lessons include having a timer count minutes since I added hardener, using a disposable cup to hold resin, having paper down to protect my workbench, and having breathing and eye protection.

So, I stared at that for a couple of days before realizing it was simply no good. I decided I could do better and ripped it off to start anew. I made a mold by cutting styro-foam to fit on the inside of the frame and shaped it as desired. I test-fit the piece several times in the process. I happened to have avoided a pitfall here: Not all resins and foams are compatible. Research what you have before using it. Alternatively, create a barrier between the foam and the resign with packing tape. 

I cut many strips of mat and added relief cuts around the ones I knew were going in tight spots. The result was a much better, stronger shape with far fewer bubbles - a much more enjoyable process. After lots of sanding and some additional fiberglass work, it's starting to look acceptable.

This guy's only real job is to hug the back of the seat. It definitely does the trick at this point, so it's just a matter of smoothing it a bit more and painting it white.

-Colby