One of the gl*** fender skirts on my car fits like hell. The "good" one fits fairly flush to the fender, the other doesn't. It's probably a difference in sheetmetal from side to side, but if it is it's not really noticeable. Is there any way to soften/reshape fibergl*** once it's set? Can it be heated and "persuaded" to be slightly reshaped? Or once it's set is that it?
unless somebody out there knows something I dont, once fibergl*** is set, the only working it is with cutting devices and more fibergl***.
Actually, yes in some cases. If the layup of the part is not too resin heavy or way thick with mat or cloth you can make some changes in the shape with carefully applied heat. You can't make abrupt changes in shape but the contour can be varied. Heat lamps usually work best so what you need to do is make some sort of fixture to hold the aprt on either side of the offending area and then apply a load to push it in the correct direction. Heat the part with the lamps and then push it into the required shape and clamp it. Let it cook under the heat lamps for a while and then let it cool while still clamped. There is a limit to how far you can mover the material with this method but it sure beats cutting and re-gl***ing. Roo
Last year a friend who is an excellent fabricator put Superior (brand) gl*** fenders on his '37 Chev Pickup. Initially they would not fit at all; not even close. A call to Superior resulted in him warming the fenders and gradually pulling them into shape. Worked well.
I've heated fenders and other parts with a heat lamp and made them fit, more than a few times. Take yer time.........OLDBEET
Fibergl*** is a thermoset plastic not a thermoform plastic, if I remember correctly. I believe with a thermoset you can't brake the secondary bond (the bond that keeps the plastic in shape) without destroying the primary bond (the bond that keeps it plastic.) However, if someone has experence doing this type of thing I could be wrong.
Depends on how long it's been "set". If it's a fairly recent layup, like some time in 2007, it's still "setting" and can and will "warp" to a different shape. That's why parts shouldnt be pulled from a mold too soon, even if they are "set" and after being pulled should be put in or on a curing support, so they don't relax, warp and sag onto whatever uneven surface they are on. For instance, a fresh body should be bolted to the frame it's going on immediately and allowed to sag itself in to it's "home" like suggested above about the fenders, Then after a period of time, months if available, the doors Fenders, skirts, etc. should be adjusted to fit, because they will have relaxed itp their forced position. Within reason... you can't bend it in a pretzel and not have it crack the gl*** fibers and shatter the resin.
I wouldn't try to bend it ...why not slice and dice till you get what you want then strengthen it from the backside. thats the beauty of FRP, you can do almost anything except bend.
Common problem on the older vettes is hood fit. I have used the heat and hold till cool method. Only good for a small amount of change. I use a oxy/acy torch but I'm not going to recommend that. I have never had a fibergl*** fire but have been told it can be a very bad experience. Good heat gun or heat lamp should do it. Steve
The heatlamp method will work, but one thing to keep in mind is that if you don't provide a very "uniform" pressure over the entire area to be "deformed" then it will show very badly.
Wow. I guess you learn something new everyday. I have worked with fibergl*** on Corvettes and other various things for well over 20 years now and I never seen it move with heat.( A tiny bit of expansion and contraction. That occours with everything) I always just cut it up move it to where I want and re gl***. It's not that hard. In short it "Befugles" me to think it would move with heat. If this was the case, wouldn't all of the fibergl*** hoods be laying on top of the carbureators after a few summers in the 100 degree sun with a 200 degree motor under them? Or will they cool down in the winter and snap back into shape? I'm not trying to question athority. I'm just trying to learn something here. Zilla!
Donzilla---You have to apply a lot more pressure to make fibergl*** move than the weight of the fibergl*** part itself. And its a gradual process, and I know that it works with polyester resin based fibergl***. I think that perhaps the Corvette fibergl*** bodies have a different (more stable) resin base. (not certain of that factoid).
I still don't understand. Fibergl*** will catch fire at aprox. 375 degrees.And once it starts it is very hard to put out. Ok a Vette hood don't weigh much, but how about a one piece hood for a tractor/ big rig. Iv'e had them off a time or two. They weigh more that one person can lift. Why don't they move? Iv'e done a couple of one piece Jeep bodies with a complet interior and such laying on them. They are supported by a couple of body bushings. Or the entire weight of a Corvette floor laying on a couple of body bushings. I would suspect that the fibergl*** with pressure and heat would stress under the pressure by maybe a bunch of tiny stress fractures, But taking on another solid form by heat and pressure. I (Iguess out of my own ignorance) can't see it. I have been wrong before and may be again this time. I don't think Corvette fibergl*** is any different from any other fibergl***. It's a pretty straight foreward thermochemical reaction. Yes everything varies a little bit, but I don' think they have any special voodo magic in them. So what I'm trying to understand is. How much heat and pressure and for how long? Someone says an electric blanket will do the trick. They hit about 100 degrees. How much pressure a couple of hundred pounds? Can an over weight guy sit on a fibergl*** chair in the sun and bend it out of shape? Just trying to learn something, Zilla
most of them have an aluminum substructure around the grill opening and along the bottom where the hinges bolt up. . .the rest is the shape itself i would imagine
Well I don't really underastand it myself. The last time I move fibergl*** was on a 76 vette hood. The crown of the top center of fenders did not match the hood. Use front with original hood. I heated a large part of the hood....put the bend to it........then cooled it with compressed air. I did not need much but it worked for me. Easier than building up the whole fender top right. Metal can be reshaped as we all know. Those little molecules get to jumpin around when they get warm. While they are jumpin around you put the pressure to them so they kinda loose their place, then while they are moved about you cool them back down so they stay put. Not trying to shine anyone on here....just the way I see it. Steve
I've been molesting fibregl*** with a heat gun for years, heat it up force it to shape,, go a little past what you actually need as it will relax some as it cools. Once you've got it wear ya want it, add a layer of gl*** to the packside. Use the mat, not the woven stuff it will hold its shape much better.I have had re-shaped pieces relax in the sunlight, thats why I suggest adding a layer to combat this.
Corvettes are not made of fibergl***, believe it or not. They are made of SMC, or sheet molding compound, and have been since the early 60s.It does have some gl*** fiber in it, but it also has silica fibers, talc,and a bunch of other stuff. You put a measured amount of SMC in a die, squeeze it down, and hit it with steam, instant part. Finished inside and out, very little t*******, and each part is the same.
most big rig hoods are made of smc(sheet molded composite) not a fiber gl*** lay up. also viper and corvette body parts are made using this process. buy the way the comany i work for made the smc mold that makes the door hinges for the viper(it was an industry first).
This is probably the gentelest way to "persade" the gl*** to move, but is also affective for what your doing. I worked at Northrop Grumman for 8.5 years as a composit layup guy, and this is one of the mild techniques we used to cohourse parts into shape.
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