Editing Make a fiberglass fan shroud (section)
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==Troubleshooting tips== 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 picture, 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. {| |-valign="top" |[[Image:41slightly stressed from shrinking too fast.JPG|center|thumb|Slightly stressed from shrinking too fast in the sun.]] |[[Image:42close up of resin rich and air bubbles.JPG|center|thumb|Air bubbles, and a resin-rich area.]] |[[Image:43resin rich.JPG|center|thumb|Resin-rich area.]] |[[Image:44good resin glass ratio.JPG|center|thumb|Proper resin/reinforcement ratio and rollout.]] |} ===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 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]]. {| |-valign="top" |[[Image:44trimming the excess.JPG|center|thumb|Trimming off the excess with a diamond saw on a die grinder.]] |[[Image:45trimmed part.JPG|center|thumb|All trimmed, ground, and ready for some body filler.]] |[[Image:46trimmed part with a fat boy.JPG|center|thumb|Use a dust mask, and proper eye and body protection when working with fiberglass dust.]] |} ===Finishing the part=== After the part has been trimmed and the surface has been lightly ground, with any high spots ground down, and any air bubbles opened up, a skim coat of body filler can be applied. Any decent body filler that will stick to fiberglass will work. Scrub a light coat into the surface in 3 or 4 directions before applying the fill coat, this will get the filler into the pores better. The part is still left on the foam and plywood buck because it is easier to handle during the bodywork phase. As this is a one-off fan shroud, special fairing techniques are not employed in its execution. A DA sander with 80 grit is used in all accessible areas, and hand sanding in the corners is done with 80 grit as well. {| |-valign="top" |[[Image:49even more bondo.JPG|center|thumb|Leave the part on the buck for ease of handling.]] |[[Image:47skim coat of bondo.JPG|center|thumb|Apply a skim coat of bondo.]] |[[Image:48more bondo.JPG|center|thumb|Some areas need another coat to level the surface.]] |} After sanding with 80 grit, a final sanding can be done with 120 grit. {| |-valign="top" |[[Image:50after sanding.JPG|center|thumb|After sanding with 80 grit.]] |[[Image:51after more sanding.JPG|center|thumb|After sanding with 120 grit.]] |} 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. {| |-valign="top" |[[Image:52chipping out rocks.JPG|center|thumb|Chiseling out the larger pieces of foam.]] |[[Image:53most of the foam out.JPG|center|thumb|Most of the foam is now out.]] |[[Image:55nice and clean.JPG|center|thumb|Nice and clean.]] |[[Image:56clean inside and out.JPG|center|thumb|Clean inside and out.]] |} As mentioned before, this shroud is going to need to enclose the radiator where the fan swings 1" above the top. This will require a secondary lamination to form a return. As the return can be flat, and on the same plane as the mounting surface, a table top will be used for the mold. I simply tape the top off with some masking tape, then wax the tape with some mold release wax. I like [http://www.rexco-usa.com/part3.htm Partall #2], aka "green wax". Just clamp the shroud to the table, and lay up 3 layers of fiberglass mat. {| |-valign="top" |[[Image:57it is hollow.JPG|center|thumb|The shroud requires a secondary lamination.]] |[[Image:58tape off the table.JPG|center|thumb|Taping off the table.]] |[[Image:59lay up the return.JPG|center|thumb|Laying up the return.]] |} Once the laminate has cured, the part can be removed from the table. {| |-valign="top" |[[Image:60pull the part.JPG|center|thumb|Removing the part from the table.]] |[[Image:61return.JPG|center|thumb|The return flange.]] |} Some pics of the final part, ready to prime. {| |-valign="top" |[[Image:62finished part.JPG|center|thumb]] |[[Image:64backside.JPG|center|thumb]] |[[Image:65ready to prime.JPG|center|thumb]] |[[Image:66rack for priming.JPG|center|thumb|The part is placed on a simple priming rack.]] |} I use polyester surfacing primer on all of my plugs and one-offs. Evercoat-Fiberglass Co. makes a material called [http://www.evercoat.com/productDetail.aspx?pID=171 Featherfill], Poly-Lux, Inc. makes a polyester surfacing primer, and [http://www.duratec1.com/ProductList.html Hawkeye Industries] (under their Duratec product line) has a line of primers that are well suited to filling all of the pores and sandscratch marks left by shaping. I like the [http://www.duratec1.com/dp04.html Duratec surfacing primer] the best, because you can build up to 0.040" in a single application. {| |-valign="top" |[[Image:67duratec.JPG|center|thumb|The Duratec polyester surfacing primer.]] |[[Image:68this primer has some solids.JPG|center|thumb|As you can see, this is a high solids primer.]] |} Nothing fancy in the way of spray guns here. The primer was sprayed with a very old Devilbiss that I bought at a garage sale for $1.00. {| |-valign="top" |[[Image:Spraying primer.JPG|center|thumb|Spraying the primer.]] |[[Image:Primered part.JPG|center|thumb|The part is now primed.]] |} 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... ===Related articles=== *[[Fiberglassing]] ===External links=== *[http://en.wikipedia.org/wiki/Polyvinyl_alcohol Polyvinyl Alcohol], ''Wikipedia'', retrieved June 26, 2007. *[http://www.osha.gov/SLTC/syntheticmineralfibers/recognition.html Synthetic Mineral Fibers -- Health Hazards], ''US Department of Labor, Occupational Safety and Health Administration (OSHA)'', retrieved June 26, 2007. *[http://en.wikipedia.org/wiki/Fiberglass Fiberglass], ''Wikipedia'', retrieved June 26, 2007. *[http://www.lungusa.org/site/pp.asp?c=dvLUK9O0E&b=35439 Facts About Fiberglass], ''American Lung Association'', retrieved June 26, 2007. *[http://www.nyc.gov/html/doh/html/epi/fiberglass-fact.shtml Fiberglass: Environment and Occupational Disease Epidemiology], ''New York City Department of Health and Mental Hygiene'', retrieved June 26, 2007. [[Category:Cooling]] [[Category:Engine]] [[Category:Good articles]] {{youcanedit}}
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