Fan shroud questions.

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harrisonm said:
Maybe I'm a little dense, but I can't picture what you mean by "DO Not make the shroud flat-it needs to be off of the radiator and flow to the fan." Do you mean not to mount the shroud flat against the Radiator? I always thought it was best to mount the shroud flat against the Radiator to keep air from leaking past the shroud and to force all the air through the radiator.
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Think cone shaped leading away from the radiator to the fan to lead the heat away, or a raised box off the back side of the radiator to lead into the electric fan, or engine driven fan. This allows space for the hot air to get away from the tubes and cooling fins.
 
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New pix. I used the all thread just to keep the circular disc part of the mould concentric and square with the radiator side of the mould until i could fit the spacer blocks, then once the drywall screws were installed , i removed the all thread as its no longer needed. An old 2x4 cut up works fine. I decided on 6 to space it out. The blocks are glued to the rectangular part of the mould.

Btw, i used cardboard strip with punch holes in it as a large circle compass to get my radiuses and circles. Works great and is free.

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I am looking at cotton T shirt material. I think that will have the right amount of stretch and be wrinkle free to use for this. Then i will likely use 3 layers of 7781 fiberglass and resin as its pretty heavy duty.
 
Also added some 2x2 to the back of the radiator side part of the mould. The masonite had a slight bow in it, plus i need something to staple the fabric to once i stretch it out. I also added a small filler piece to the top where the shroud will butt up against the upper radiator tank.

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Ok heres the latest. I stretched over release film on the circle, and put release tape on the edges of the square plate. I cut up an old cotton Tee shirt. Stretched it over, stapled it in place, and resin coated it. I have no pix of the fiberglass resin coating yet.

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I cant wait for the resin to dry, so i can scuff it and apply coat #2 then pop it out of the mould when coat #2 is dry. Then its onto fiberglassing the inside. Still its nice to see it coming to fruition.
 
moparmat2000 said:
I cant wait for the resin to dry, so i can scuff it and apply coat #2 then pop it out of the mould when coat #2 is dry. Then its onto fiberglassing the inside. Still its nice to see it coming to fruition.
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Looks like the shape will be perfect!
 
First resin coat. The cotton makes it a little bumpy. I will sand that off and resin coat it with coat #2 later today

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Furyus2 try an aircraft composite supply place. But that may be expensive. You can prob trim out and use plastic trash bag as well. Anything like that the resin wont stick to. Maybe test try some resin on the tape and plastic film you want to use to see if when dry it pops loose easily.

I would not recommend using pam or anything oily as it will wick into the fabric and contaminate it, and it will be hard to get the resin to stick when you add fiberglass to the cloth later.
 
Mylar may work. Just have to test a piece of it with resin on it and see if it releases. The resin i used is pretty liquidy. Takes forever to dry too.
 
Ok, it got a few small wrinkles in the fabric. I think it got too warm in the sun. I put second coat on it, and when dry i popped it out of its mould. Its pretty flimsy. I reinstalled it on the mould and will put one layer of fiberglass on the outside of it. I am hoping this will stiffen it up a bit so i can put multiple layers of fiberglass the inside and not distort it. The minor wrinkles i can fill up and smooth out with some body filler and high build primer.
 
One thing I didn't think about until you mentioned it got a little wrinkly is the fact that if you get a t-shirt wet it can stretch fairly easily, when you wash it and it dries it goes back to normal but since you made it wet with resin it may have stretched a little and can't return to normal as it dries since the resin is hardening as it dries. Just my theory anyway.
 
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75slant6 said:
One thing I didn't think about until you mentioned it got a little wrinkly is the fact that if you get a t-shirt wet it can stretch fairly easily, when you wash it and it dries it goes back to normal but since you made it wet with resin it may have stretched a little and can't return to normal as it dries since the resin is hardening as it dries. Just my theory anyway.
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I think i made the mistake not drawing it down tight enough, and trying to kick off the resin with a heat lamp when it didnt seem to be drying. The fabric sagged slightly with the heat lamp, then hardened in that shape, plus i used a slow cure hardener the first time.

I decided to make a second one and I used a fast cure hardener this time. I will not use a heat lamp. The other shroud is savable, i would need to put a little body filler in the bumpy areas to smooth it out. Since i am OCD i cannot have that, i am currently making another, and will not rush it this time.
 
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Shroud part deux. I have 4 coats of fast drying resin brushed on, and i am letting the sun dry it, not using a heat lamp. No wrinkles, and the resin coats smoothed out a lot of the bumpyness.

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Ooohhh shiny!! I'm guessing the 2nd pic was taken first and the first pic was after more coats?
 
Nope, both taken the same time. Going to let this one dry overnight so its definitely solid. When i fiberglass the inside, i may form and bond in some sheetmetal flat strap inside where the top and bottom center areas are. Even with fiberglass to stiffen things up it may still be weak.
 
Popped it from the mould. Looks great, between the resin coating and the cotton fabric, its really flexible i am going to fiberglass the inside of it on friday. Hopefully that will stiffen it up a bit. Sorry no pix. Will post some later.
 
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