Editing Make a fiberglass fan shroud

This will be a pictorial article showing one way to build a fiberglass fan shroud. The techniques used in this article can be applied to just about any part that can be construced from fiberglass, I will work on it as time permits.

This is a radiator in a 1961 Ford Galaxie that needs a fan shroud. Start by measuring all of the dimensions, taking care to think about how the shroud will attach to the radiator, if there are any obstructions you need to take into consideration, how far away the fan is from the radiator and if there are any angles or off center components. This fan is off center towards the passenger side by about 1/2 inch, sets back about 1 3/8" ,and it swings about 1" above the top of the radiator. It is parallel with the radiator, and there are no hoses or other obstructions to deal with on this particular project.

[[Image:161_starliner_radiator.JPG|center|600px|1961 Ford Galaxie radiator.]]


[[Image:261 Starliner rad rh.JPG|center|600px]]

Using a piece of thin plywood is a good way to start on any part that has a flat mounting surface. The plywood gives a sturdy base upon which to lay out and construct your foam buck. 

[[Image:3start laying out.JPG|center|600px]]


[[Image:4laid out.JPG|center|600px]]

I had a bunch of 2 lb polyurethane foam left over from other jobs, so I thought this project would be a good place to use some up.
It also can illustrate how easy it is to use this foam, it cuts so easy and shapes so well that it doesn't add all that much time to the project to peice it up. This foam is available in thicknesses from 1/2" up to 6" thick at any fiberglass supply house, and you can also use the polyurethane insulating foam that is available from building supply stores. Just peel the foil layer off. (Keep in mind that styrofoam won't work under any resin with styrene in it, unless you can bar the resin from it)
[[Image:7box o scrap foam.JPG|center|600px]] 

Cutting foam to shap with a handsaw, putty knife or bandsaw, fit and glue peices of foam larger than your layout on the board. A hot melt glue gun makes gluing this foam fast and easy. You can use one of the expanding uethane glues or some of the expanding foam in an aerosol can to glue the foam down. The different glues can make sanding over seam lines a pain , as they are usually a different density and hardness than the surrounding foam. 

Shaping this foam can be done with sandpaper, sureform files, knives and picks, even your fingers can shape this foam quite easily and rapidly.
[[Image:5start foam.JPG|center|600px]]

 

[[Image:6scribe a circle.JPG|center|600px]]

[[Image:8laying out the circle.JPG|center|600px]]

Keep the hot melt glue away from where you will be sanding, it is gummy and will not sand properly, making your buck alot harder to shape than it needs to be.

[[Image:9it's hot melt glue.JPG|center|600px]]

I knew that one part of the shroud was going to be perfectly round, so I set it up with a bolt in the center and made it so it could be spun by hand against an end mill to shape the circle as well as cut the box section down to it's proper thickness.

[[Image:10fast way to make a perfect circle.JPG|center|600px]] 

[[Image:11more shaping.JPG|center|600px]]

[[Image:13roughed out some more.JPG|center|600p]]

[[Image:14edge detail.JPG|center|600px]]

[[Image:15final shape.JPG|center|600px]]

[[Image:16more final shape.JPG|center|600px]]I made a small miscalculation in laying out my initial circle, so I needed to add a bit to the outer edge.

[[Image:18even still more final shape.JPG|center|600px]] 

One step that I do on these kinds of parts is to paint the buck with resin after shaping it. It makes it a little more dmensionally stable, and toughens up the surface for the next steps.



[[Image:19paint with resin.JPG|center|600px]]

Once I have painted the buck with resin I can clay up any low spots, and then wax the resin. I then spray a coating of Poly Vinyl Alchohol, (PVA), on the waxed surface. This easy step will make removing the foam much easier after the part is laid up.

[[Image:20wax and PVA.JPG|center|600px]]