Make a fiberglass fan shroud
(→General Comments on Fiberglassing) |
(→General Comments on Fiberglassing) |
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'''DBM''' - dual bias mat roving which is two roving mats stitched together with the weaves @ 45deg for morhe strength. For the boat guys, not us. | '''DBM''' - dual bias mat roving which is two roving mats stitched together with the weaves @ 45deg for morhe strength. For the boat guys, not us. | ||
| − | '''Graphite''' - really exotic looks purty and necessary for the 350mph crowd, not so much for us shade tree guys. To be purty, must be laid up in epoxy resin in shiny female molds. Is fairly brittle so commonly has a layer of aramid cloth for toughness. | + | '''Graphite''' , also called carbon fiber- really exotic looks purty and necessary for the 350mph crowd, not so much for us shade tree guys. To be purty, must be laid up in vinyl ester or epoxy resin in shiny female molds. Is fairly brittle so commonly has a layer of aramid cloth or fiberglass for toughness. Ths stuff is sized in thousands of filaments, i.e. 1K, 5K, 12K, etc. |
'''S-glass''' or '''E - glass''' - these are high quality woven glass that is measurably stronger than regular woven fiberglass. More expensive and not necessary in most of what we do. | '''S-glass''' or '''E - glass''' - these are high quality woven glass that is measurably stronger than regular woven fiberglass. More expensive and not necessary in most of what we do. | ||
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good old '''polyester resin''' - use for 99.99% of what we do. It come in several types - | good old '''polyester resin''' - use for 99.99% of what we do. It come in several types - | ||
| − | '''Ortho''' (made with orthopthalic acid) is what you get if you don't specify anything else. Fine for everything we do. | + | '''Ortho''' (made with orthopthalic acid) is what you get if you don't specify anything else. Fine for most everything we do. |
| − | '''Iso''' (made with isopthalic acid) bonds a little better than ortho but costs more and again ortho is fine for our tasks. | + | '''Iso''' (made with isopthalic acid) bonds a little better than ortho but costs more and again ortho is fine for our tasks. An added benefit to using "iso" resin is that it is more heat resistant than ortho resin, it will withstand 210* F as opposed to 170* f for most ortho resins. Iso resin is also called "tooling" resin, because it is designed for moldmaking, and can withstand many heat/cool cycles and remain dimensionally stable. |
| − | '''Waxed resin''' - be sure you check whether you have 'laminating' or 'finsinh coat' resin. The former is just plain resin and is used for laying up several layers. Every layer will stick to the previous one very well. The latter contains a wax that floats to the surface of the finisned part and, if used in laminating layers, will prevent the layers from bonding causing part failure. These two resin mixtures are necessary. Polyester resin will harden all the way through except for the very outer surface which is exposed to oxygen. This exposure prevents the resin from hardening and results in an irritating sticky feel to the surface. Using the waxed resin in the final layer allows the wax to float to the surface, insulate the surface from oxygen, allowing it to fully harden. I only use laminating resin and and sand off the outer surface or prime it which seals and hardens it. No biggie, don't worry about it, just be careful to not laminate with finishing resin! | + | '''Waxed resin''' - be sure you check whether you have 'laminating' or 'finsinh coat' resin. The former is just plain resin and is used for laying up several layers. Every layer will stick to the previous one very well. The latter contains a wax that floats to the surface of the finisned part and, if used in laminating layers, will prevent the layers from bonding causing part failure. These two resin mixtures are necessary. Polyester resin will harden all the way through except for the very outer surface which is exposed to oxygen. This exposure prevents the resin from hardening and results in an irritating sticky feel to the surface. Using the waxed resin in the final layer allows the wax to float to the surface, insulate the surface from oxygen, allowing it to fully harden. I only use laminating resin and and sand off the outer surface or prime it which seals and hardens it. No biggie, don't worry about it, just be careful to not laminate with finishing resin! Another common name for this resin is "sanding resin". |
'''Gel coat''' - this is resin filled with a high solids usually colored pigment. It can either serve as a primered surface to be sanded and painted or as in the case of boats, can be the final colored finish. It is sprayed in a polished female mold without reinforcement, then 'glas is laminated on it. It is much softer than plain resin and works like a sanding primer. Good stuff. | '''Gel coat''' - this is resin filled with a high solids usually colored pigment. It can either serve as a primered surface to be sanded and painted or as in the case of boats, can be the final colored finish. It is sprayed in a polished female mold without reinforcement, then 'glas is laminated on it. It is much softer than plain resin and works like a sanding primer. Good stuff. | ||
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'''Epoxy''' - much stronger than polyester but more persnikety (I think that's a word!) and expensive. Also check with the supplier for compatibility 'cause some cloths won't work with some resins. I would only use this for looks if making a carbon fiber part. | '''Epoxy''' - much stronger than polyester but more persnikety (I think that's a word!) and expensive. Also check with the supplier for compatibility 'cause some cloths won't work with some resins. I would only use this for looks if making a carbon fiber part. | ||
| − | '''Vinyl Ester''' - this is a stronger version of polyester resin and somewhere between polyester and epoxy in strength. Not needed in what we do. | + | '''Vinyl Ester''' - this is a stronger version of polyester resin and somewhere between polyester and epoxy in strength. Not usually needed in what we do. Vinyl ester is much more heat resistant than either of the polyester resins, and also chemical resistant. It also shrinks alot less, so print-through is less of a problem. If you want to easily make some very strong, rigid and lightweight parts, use vinyl ester resin, along with either fiberglass mat or cloth, and add a layer of 6 oz carbon fiber in the middle of the laminate. |
As far as how much to use depends on the part you are making. If I were making that fan shroud I would lay up two layers of mat over most of it and reinforce all the edges with a third layer. All 2 oz mat. This would give a very light weight body, a little less than 1/8" thick and stronger edges a little more than 1/8" thick. | As far as how much to use depends on the part you are making. If I were making that fan shroud I would lay up two layers of mat over most of it and reinforce all the edges with a third layer. All 2 oz mat. This would give a very light weight body, a little less than 1/8" thick and stronger edges a little more than 1/8" thick. | ||
| − | A body part would need a couple layers of 2oz mat, a layer of 1.5oz plain weave cloth and possibly a third layer of mat, depending on size. Again reinforce edges as required with a strip of mat. | + | A body part would need a couple layers of 2oz mat, a layer of 1.5oz plain weave cloth and possibly a third layer of mat, depending on size. Again reinforce edges as required with a strip of mat. You can also reinforce edges with woven tape, this puts many continuous unbroken filaments parallel with the edge of a part, and will make it much more resistant to cracking from the edge in. |
I made a shell for the headliner of my '53 Chevy pickup and used only 2 layers of mat (about 3/32" thick) for light weight and flexibility. It is more than strong enough. See it here [http://www.hotrodders.com/forum/journal.php?action=view&journalid=2439&page=25&perpage=5&reverse=]. This is also an example of a part made from a finished mold (the painted roof of the truck), but without the gel coat since it is coverd with upholstry and doesn't need a paitable finish. | I made a shell for the headliner of my '53 Chevy pickup and used only 2 layers of mat (about 3/32" thick) for light weight and flexibility. It is more than strong enough. See it here [http://www.hotrodders.com/forum/journal.php?action=view&journalid=2439&page=25&perpage=5&reverse=]. This is also an example of a part made from a finished mold (the painted roof of the truck), but without the gel coat since it is coverd with upholstry and doesn't need a paitable finish. | ||
A comment on using polyester resin - you can adjust it's hardening time somewhat with the amount of MEKP hardener you add. The more hardener, the faster it sets. You can add too little hardener and it will never set. It isn't that scary, there is a pretty wide range of hardener concentration that works fine. If you have a piece that isn't setting due to cold weather or short hardener you can set the piece in direct sunlight. UV radiation will set off this resin seems like no matter how much hardener is used. Be careful with this though, the resin setting chemistry gives off a lot of heat and too thick a part, too much hardener and/or solar acceleration can get the thing smoking and even start a fire! Closest I came to that was mixing several batches of resin in a row in a tin can and just starting the next batch on top of a gelling existing one. Got to about half a inch thick and it started bubbling, smoking and WAY too hot to touch the can. | A comment on using polyester resin - you can adjust it's hardening time somewhat with the amount of MEKP hardener you add. The more hardener, the faster it sets. You can add too little hardener and it will never set. It isn't that scary, there is a pretty wide range of hardener concentration that works fine. If you have a piece that isn't setting due to cold weather or short hardener you can set the piece in direct sunlight. UV radiation will set off this resin seems like no matter how much hardener is used. Be careful with this though, the resin setting chemistry gives off a lot of heat and too thick a part, too much hardener and/or solar acceleration can get the thing smoking and even start a fire! Closest I came to that was mixing several batches of resin in a row in a tin can and just starting the next batch on top of a gelling existing one. Got to about half a inch thick and it started bubbling, smoking and WAY too hot to touch the can. | ||
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