Make a fiberglass fan shroud
(→Laminating the part) |
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#How much clearance is needed aroung the fan to allow for engine or body movement? | #How much clearance is needed aroung the fan to allow for engine or body movement? | ||
| − | For example, this fan is off-center towards the passenger side by about 1/2 | + | For example, this fan is off-center towards the passenger side by about 1/2", 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. |
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===Constructing the foam buck=== | ===Constructing the foam buck=== | ||
| − | Using a piece of thin plywood is a good way to start on any part that has a flat mounting surface. The plywood provides a sturdy base upon which to lay out and construct the foam buck. | + | Using a piece of thin plywood is a good way to start on any part that has a flat mounting surface. The plywood provides a sturdy base upon which to lay out and construct the foam buck. It will also serve as the form for the finished fan shroud's mounting flanges. |
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. | 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. | ||
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Shaping this foam also can be done with sandpaper, sureform files, knives, and picks. Even your fingers can shape this foam quite easily and rapidly. | Shaping this foam also can be done with sandpaper, sureform files, knives, and picks. Even your fingers can shape this foam quite easily and rapidly. | ||
| − | Keep the hot melt glue away from where you will be sanding. It is gummy and will not sand properly, making your buck | + | Keep the hot melt glue away from where you will be sanding. It is gummy and will not sand properly, making your buck a lot harder to shape than it needs to be. |
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===Forming the circular part of the shroud=== | ===Forming the circular part of the shroud=== | ||
| − | It's often the case that part of the shroud will need to be perfectly round. If so, set up the buck with a bolt or nail in the center, and fix it to your drill or mill table so that it can be spun by hand against an end mill. ( A drill bit or drum sander works well also.) This will make it easy to shape the circle, as well as cut the box section down to its proper thickness. There are many other ways to shape your buck. You are only limited by your imagination here. | + | It's often the case that part of the shroud will need to be perfectly round. If so, set up the buck with a bolt or nail in the center, and fix it to your drill or mill table so that it can be spun by hand against an end mill. (A drill bit or drum sander works well also.) This will make it easy to shape the circle, as well as cut the box section down to its proper thickness. There are many other ways to shape your buck. You are only limited by your imagination here. |
You will notice a small ledge left at the intersections of the vertical and horizontal surfaces. This will be sanded into a radius by hand during the final sanding. | You will notice a small ledge left at the intersections of the vertical and horizontal surfaces. This will be sanded into a radius by hand during the final sanding. | ||
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Cut strips of 1 1/2 oz fiberglass mat on a peice of cardboard, ready to be wetted out. 3 layers of 1 1/2 oz mat will make a part that is about 0.120" thick, as each layer contributes about .040" to the laminate. There will be an extra layer laminated around all of the edges to make the final part about 0.160" thick. | Cut strips of 1 1/2 oz fiberglass mat on a peice of cardboard, ready to be wetted out. 3 layers of 1 1/2 oz mat will make a part that is about 0.120" thick, as each layer contributes about .040" to the laminate. There will be an extra layer laminated around all of the edges to make the final part about 0.160" thick. | ||
| − | When wetting out mat with resin, many people work the resin into the mat while it is on the wet out board. This is a mistake and will only make a resin rich, | + | When wetting out mat with resin, many people work the resin into the mat while it is on the wet out board. This is a mistake and will only make a resin rich, inconsistent part. You only brush enough resin on to cover the mat with resin. Then, give it a little bit of time, and it will soak in. |
Notice in the picture how there are some areas of mat that are darker, and have become transparent. There is no more resin on those strips than is on the others, they were wetted out earlier and have soaked up the resin. | Notice in the picture how there are some areas of mat that are darker, and have become transparent. There is no more resin on those strips than is on the others, they were wetted out earlier and have soaked up the resin. | ||
| − | You do need to be somewhat swift with this part of the laminating process | + | You do need to be somewhat swift with this part of the laminating process. As time goes by the resin will dissolve the binder that holds the mat together and make picking it up to apply it to the part a very frustrating activity. If the binder has dissolved, the mat will just fall apart when you try to pick it up. |
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| − | Pick up the material from the wet out board and apply it to the part. Don't try to push it | + | Pick up the material from the wet out board and apply it to the part. Don't try to push it into any inside corners or stretch it over any outside corners just yet. Just get the material stuck to the major flat areas. |
Stretch the material over any outside corners, but don't try to fold it as it will only spring back. Push the material into inside corners, stretching it as you go. If it gets thin, more material can be added. I usually stretch the material, and wind up with a section of mat that I can reapply to the stretched, thinned out areas. | Stretch the material over any outside corners, but don't try to fold it as it will only spring back. Push the material into inside corners, stretching it as you go. If it gets thin, more material can be added. I usually stretch the material, and wind up with a section of mat that I can reapply to the stretched, thinned out areas. | ||
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I made a roller out of some threaded rod, a file handle and some 1/4" rod. It works extremely well for rolling out air bubbles in fiberglass. Move slowly, applying enough pressure to roll the air out, but not so much pressure that you move the mat around or push all of the resin out. Air bubbles look like clear voids, they are easily spotted when you put pressure on them as you can move them around."Dry" spots will show up as white strands of fiberglass that spring up out of the resin. | I made a roller out of some threaded rod, a file handle and some 1/4" rod. It works extremely well for rolling out air bubbles in fiberglass. Move slowly, applying enough pressure to roll the air out, but not so much pressure that you move the mat around or push all of the resin out. Air bubbles look like clear voids, they are easily spotted when you put pressure on them as you can move them around."Dry" spots will show up as white strands of fiberglass that spring up out of the resin. | ||
| − | + | Use consistent, firm pressure, moving steadily. It works better to pull the roller than to push it. | |
| − | You can also use a brush, foam roller or your fingers to manipulate the air out. Squeegees don't work well on mat. Commercially made rollers of many sizes and shapes are | + | You can also use a brush, foam roller or your fingers to manipulate the air out. Squeegees don't work well on fiberglass mat. Commercially made rollers of many sizes and shapes are available from most fiberglass supply houses. |
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| − | Cut your material so that you have at least 1" of overlap onto the previously laid up section. Stagger the layers so you don't create a big lump. A trick that professional glass guys use is to tear the edges of the mat. This tapers the thickness down at the edge, making a smoother overlap. Done correctly and applied while the previous lay up is still workable, you won't be able to tell that the part was made from separate pieces of mat, instead of | + | Cut your material so that you have at least 1" of overlap onto the previously laid up section. Stagger the layers so you don't create a big lump. A trick that professional glass guys use is to tear the edges of the mat. This tapers the thickness down at the edge, making a smoother overlap. Done correctly and applied while the previous lay up is still workable, you won't be able to tell that the part was made from separate pieces of mat, instead of one continous piece. |
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| − | Below are several troubleshooting pictures. In the first picture, the white streaks and crosses are the result of a slightly stressed part | + | Below are several troubleshooting pictures. In the first picture, the white streaks and crosses are the result of a slightly stressed part; this one was from the laminate being in the sun and curing too fast in that spot. It is the resin shrinking and pulling the fibers apart that causes that appearance. The second picture shows some air bubbles, in the center-right of the pic, and a resin rich area. The fibers are almost floating on the resin, and the appearance is one of shiny, glossy, pure resin, with a very low reinforcement ratio. The air shows up as misshapen, somewhat opaque objects in the laminate. On an exterior body part, air bubbles would not be acceptable. In this case, it's just the underside of a fan shroud, so it will work just fine. The air bubbles can be ground out, and filled. |
The third picture shows another shot of a resin-rich area, and the fourth picture shows a proper resin/reinforcement ratio. Note how the laminate has a dull finish, with the fibers at the surface, but with no dry areas. The fibers should have a somewhat "flattened" appearance -- this indicates a tight rollout. | The third picture shows another shot of a resin-rich area, and the fourth picture shows a proper resin/reinforcement ratio. Note how the laminate has a dull finish, with the fibers at the surface, but with no dry areas. The fibers should have a somewhat "flattened" appearance -- this indicates a tight rollout. | ||
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===Trimming the part=== | ===Trimming the part=== | ||
| − | I use a diamond saw on a die grinder to trim parts, but you can use a grinder with a 24 grit disc | + | I use a diamond saw on a die grinder to trim parts, but you can use a grinder with a 24 grit disc or sawzall just as easily. |
Fiberglass is very messy, and the dust is quite a nuisance, as shown by the dust that has accumulated on our test dummy. Though fiberglass dust and fiberglass strands are generally not considered to be carcinogenic (except in cases of uncommonly high exposure), they are widely recognized as skin, eye, and respiratory irritants. Use of a minimum N95 dust mask, and proper eye and body protection is a must. Don't do this in your house, or anywhere without adequate ventilation. The dust will migrate everywhere if you don't exhaust it, or collect it. For more information on the health factors associated with fiberglass, see this article's [[#Related_resources|Related resources]]. | Fiberglass is very messy, and the dust is quite a nuisance, as shown by the dust that has accumulated on our test dummy. Though fiberglass dust and fiberglass strands are generally not considered to be carcinogenic (except in cases of uncommonly high exposure), they are widely recognized as skin, eye, and respiratory irritants. Use of a minimum N95 dust mask, and proper eye and body protection is a must. Don't do this in your house, or anywhere without adequate ventilation. The dust will migrate everywhere if you don't exhaust it, or collect it. For more information on the health factors associated with fiberglass, see this article's [[#Related_resources|Related resources]]. | ||
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| − | Now the foam buck can be chiseled out. It is very soft and offers little resistance to removal. The wax and PVA that were applied to the buck are making it easy to | + | Now the foam buck can be chiseled out. It is very soft and offers little resistance to removal. The wax and PVA that were applied to the buck are making it easy to separate the foam from the part. Most of it just pops right off, but a blow gun can be used to remove the smaller flakes. |
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| − | Some pics of the final part , ready to prime. | + | Some pics of the final part, ready to prime. |
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Now that this part is primed with the polyester coating, it can be sanded and top coated with whatever paint system you like. | Now that this part is primed with the polyester coating, it can be sanded and top coated with whatever paint system you like. | ||
| − | Also, if I was going to make several of these parts, I could sand and polish the surface, wax it and use it to create a mold with which I could duplicate it many times over... | + | Also, if I was going to make several of these parts, I could sand and polish the surface, wax it, and use it to create a mold with which I could duplicate it many times over... |
===Related resources=== | ===Related resources=== | ||
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