Custom Fiberglass Speaker Boxes
Fiberglass materials allow for custom shapes and features. A very popular Do It Yourself project is custom speaker boxes for automobiles.
To accomplish this, it is important to begin with a solid foundation material. Very often this is wood, which allows for screwing and stapling. Next, the speaker mounts need to be properly attached. Orientation of the mounting surface is established for the speaker that will be used in the finished installation.
Fleece fabric material is one method that is used to span the surfaces and transition across the different areas. This material allows for smooth transition, holds staples, is easy to work with, and is inexpensive. Once it is in place it can be covered with resin and fiberglass to establish a solid surface. This can be sanded smooth and painted for full effect.
WestCoastCustomsTV demonstrates how the fleece is applied in the video below:
Compression Molding Large Vehicle Parts
Compression molding with composite resins can yield very durable, strong, and well-engineered parts.
Placing reinforcements (usually fibered glass) and resin in a heated metal mold before compressing it under high temperatures will result in a finished piece with very unique properties. The parts made in these matched metal molds have very repeatable properties, high strength to weight ratios, and are corrosion and chemically resistant. The parts can be painted, and have many positive design attributes.
Ashley Industrial Molding is a company that manufactures such parts. These large parts are made with compression and RIM molding for customer such as John Deere and Case tractors. They have a good video demonstrating their equipment, processes, and finished parts.
A couple of design considerations
FRP Composites have their own special set of considerations in design and use. And we will discuss a few here. The traditional fiberglass (unsaturated polyester with glass reinforcement) uses gelcoat on the molded (decorated) side. This is really only one side of the part, as this is not a matched-mold process. So the back side needs to be hidden from view or covered with another material, etc.
A boat, for example has a Deck and a Hull that are mated together so that the back sides of the parts are hidden from view. The inside of the cabin is then upholstered and trimmed out for comfort and decoration.
I have worked with fiberglass tabletops before where the top side is gelcoated in a decorative finish and the edge wraps down and trimmed. All of the unsightly surfaces face the floor where they cannot be viewed.
There are a few closed-mold processes that can be implemented, but these really only achieve a Class B surface out of the mold. With rework and repair, a Class A surface can be accomplished. I know of some folks that make Boat Access Hatches where they repair the backside (bottom) and rework it so it looks pleasant when opened.
Molded-in features must be used with caution. Sharp edges must be avoided because the process hates having to get resin and reinforcement into them, and because they can be stress concentrators.
Parts also need to have a minimum of 2-5 degrees of draft or angle in the pull direction so they can be removed from the mold. Molded in undercuts and reverses with multipiece molds add extreme expense and difficulty. Molded-in holes are not general practice because the process does not allow for crisp edges on these details.
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