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cardboard body to fiberglass body.

61K views 46 replies 20 participants last post by  russcomp 
#1 ·
I have been working on a project to build my own body using the pontiac fiero frame that is base on the lamborghini gallardo. I have built the entire body out of cardboard and MDF. Now I want to take this cardboard body and apply fiberglass to it leaving the cardboard as the substructure which I have been told is do-able, my question is how do I begin to do this is it just as simple as applying cloth and resin over these peices and letting it cure. Any help suggestion or advice would be greatly appreciated. Also can I/ or should I use fleece for this type of application.
 

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#2 ·
Cool...
The place to start would be to soak the 'board with resin before you start laying 'glass. Once you have the structure glued up, lay a few layers of glass over the now resin impregnated cardboard. I wouldn't put a lot of 'glass on the outside though. What you want to do is stiffen the panels up enough so you can pull them off and build up the structure on the inside. I would also look into smoothing some of your rough/sharp corners while you are doing this. Once the outside is stabilized you can trim some of the sharper inside corners so your glass will lay around the corners better.
Using t-shirt material can be tricky but it is an easy way to "blend" sharp inside corners without adding a lot of weight or substructure. Do the same thing with the cloth as you did with the initial cardboard substrate. Soaking it in resin will stiffen it up enough so it will hold it's shape as you apply glass mat and cloth.
Have fun and wear protection when you are working with the 'glass. Eyes and lungs do not take kindly to glass fibers floating around.
Mark
 
#3 ·
Thanks,
What kind of glass mat do you recommend using and and is there any difference in the types of resin. I have heard to use 6oz. and should I use cat hair on the backside or more mat. Thanks again for the info you seem to be the first person to understand what I am trying to do everyone else assumed I was removing the cardboard. This will be a great help to me I will post more pictures after I soak the cardboard in resin.
 
#5 ·
One oddball thing to be aware of. I did a somewhat similar project many years ago but used a combination of wood veneer and aluminum flashing material to provide the "base" for laying up the glass. On the larger aluminum sections which spanned anything beyond a foot or two between supports, I got an awful lot of warping. My analysis was the warps were caused by the heat created when the resin curred and bent the thin aluminum.

Keep an eye out for this problem as you proceed and give us a report on whether or not you get any similar sort of reaction. Might have been just a one time thing related to my procedure, but also might be a potential problem that needs to be dealt with when using this sort of building technique. Also might not be a problem at all with the structural makeup of cardboard.

Dewey
 
#6 ·
You asked about the choice of mat. I'd use 1.5 oz/sq. ft. mat in several layers. The total that you mentioned of 6 oz of glass per sq. ft. is reasonable, but you want a reasonably thin and flexible mat in order to make it around curves and corners without getting excessive springback, in my opinion. Thus, better to arrive at your 6 oz total in 4 layers than trying to get there in one. Also, a mat in the range of 1.5 oz is reasonably easy to wet out, and anything much heavier will get increasingly difficult. You can also include a layer of glass cloth or woven roving if you want to add a lot of extra strength, but its not typically necessary. If you do decide to use an alternate fabric, be sure to put a layer of mat on both sides of it.

Be sure to use a serrated roller, they're not that expensive and very helpful.

The preferred type of resin to use for this would be an isophthalic-based polyester. If you can't conveniently find one, a general purpose resin will also work, you'll just be giving up a bit of heat distortion temperature and a bit of strength properties. Probably a more critical thing is to get one with a reasonable gel time- using one that is very fast, as might be used for chopper gun applications, will have you spending all your time mixing up very small portions and the process will get very tiring in a hurry.

I agree with cboy's comment that warpage will likely be an issue for you. It's caused by the fact that these materials will tend to have some shrinkage as they cure, even though that shrinkage might be relatively small compared to other types of resins. You may be able to reduce the warpage some by first applying a single layer of laminate to both sides of your cardboard before building up successive layers of laminate, if possible. Anything that you can do to brace your cardboard so as to help control warpage would probably be well advised.

One thing that I differ in opinion with some previous comments is, I would not allow a first coat of resin to gel without putting glass mat in it! I'd simply brush my first layer of resin onto the cardboard and then proceed with laying the first layer of laminate into it and proceed with wetting it out with your serrated roller. A hand layed laminate is almost always on the resin-rich side unless your using an exotic technique. I think your risk of getting cracking on that layer of resin that wets out the cardbord in the absence of mat outweighs any other considerations. This is my opinion based on theory only, as I do not personally generally laminate over cardboard- perhaps someone else on this board with experience in doing so might want to comment as well.

You mentioned considering using tiger hair or kitty hair on the backside of the cardboard. I'd far prefer to simply use glass mat and resin, with the exception being if you have certain areas that have sharp interior corners or tight curves that would tend to give you springback problems (the layer of glass mat springing away from the corner rather than conforming to the curve) then a glass-filled putty like tiger hair would be an excellent choice to use in those areas. Just make sure you get your putty or tiger hair layer as smooth as possible, so that your laminate won't have trouble covering it evenly without leaving voids.

Having said all this, the real work involved in this project is going to be getting the laminate smoothed down to give a smooth surface on the final appearance surface. That's the reason that most laminates are layed into female molds, with the surface that contacts the mold being the final appearance surface. My suggestion would be for you to make up a relatively small "test" layup on a trial part to make sure that you're going to be satisfied with the final result, and comfortable with the amount of work required to achieve your final appearance, before you begin laminating over the entire body. The alternative approach, of course, is to use putty over your body to create a male buck, then laminate a female mold over that male buck, then finally laminate your actual part into the female mold. It's a good deal of work either way.

Best of luck on your project, and please post some updates of how you get along!
 
#9 ·
Just to clarify my comment about soaking the cardboard first. I have done this a number of times and I find the cardboard will suck up a lot of the resin at first. Trying to lay mat or cloth over dry cardboard takes a lot of resin and usually ends up as a mess with a lot of un-adhered mat. I just found it easier to soak the cardboard first and then lay mat. I haven't had any delamination problems with this process but I would suggest not waiting before throwing mat at the structure. I usually let the first coat kick and then immediately (while it is still "tacky") start laying up 'glass. This process will allow the first and second coats to bind together and should produce excellant results. This is my experience only, it may not be the "correct" process but it has worked well so far...
Mark
 
#11 ·
I have never done anything that size but I don't think warpage should be a huge problem. The resin generally kicks pretty quick and, once it is done cooking, the panel will not move unless it is physically twisted or bent.
Any additional wetting while 'glassing will be invisible to the cardboard. For something like a door panel I would start with some 1/8th thick masonite, Just for the additional strength, which requires less glass. Even foamcore artists board would work well and it is very light. This is what I plan to use when I rebuild the interior for the Bad Ast Project. Cutting the foamcore on one side allows it to be bent and shaped a bit. Covering that with the stretchy t-shirt material smoothes out the surface without a lot of work and makes for a very strong structure when 'glassed over.
Mark
 
#12 ·
You guys are all awsome. the information you have given is the best and most detailed I have ben given everyone else I asked just seemed to sort of lose interest when I tell them Im building a car out of cardboard and tell me its too much trouble and give me the brush off. Let me give you some back ground on the project up to now. I don't have loads of money but I do have alot of imagination and a keen mind for detail. A background in computer aided drafting and animation doesn't hurt either. I point this out to say that I am not just some guy with too much time on my hands. I have research this for several years and the opportunity finally presented itself. When I found a 86 Fiero GT and the owner only wanted $200 for it. So I jumped on it. I searched the internet for kits but none quite did it for me there was always something off about most of the kits I saw. So I decided to build my own. I took the measurements for the Gallardo and the measurements for the fiero and drew both cars in my computer then overlaid the images and adjusted the Gallardo body to fit on the Fiero frame which eliminated the need to stretch the car which would be way too costly for me. I then made templates of all the pieces in my computer. Plotted those pieces out full size. Then transferred those pieces to cardboard. The Gallardo as you may know is very knife edged so there aren't many curves or compound curves except at the fender and wheel wells. I used double corrugated cardboard which is strong but can easily be formed and cut. Where need I built framework to support these cardboard shells out of wood and MDF. On some parts I was able to use existing body part such as the door skins and mount my cardboard shell directly to the original body part so it goes back on the car using the original mounting holes. I am 80% done with the car and I had one nagging problem ahead of me which I'm sure by now you have figured out. I cant drive a car made out of cardboard.(Can You?) The fiero body as I'm sure you know is all Fiberglass. So my problem was I had to get all my cardboard pieces fiber glassed. I have no experience in this area. It looks easy but I know its not and it looks like you guys are master of the art. So I decided to see if you guys had any suggestions or tips. Like I said before it is not finished and I plan on driving it when its finished.Photo's I posted are about six months old I have completed the front bumper and fenders now. I am now working on mounting the headlights from a 2004 Toyota Celica in the hood of the car. I used the taillights from a 2006 ford expedition(that's what you see in the photos they are turned on their side). Like I mentioned I'm basing it off of the Lamborghini Gallardo but for obvious reasons it has taken on a design of its on since I had to design around the frame of the fiero. (several tweaks have been made to the body since these photo's it was looking a little boxy in the rear.)

Keep the info coming guys it is all appreciated I want this project to be as good as it can be. I have also been worried about the cardboard warping when I apply the resin and it get wet but I have tried to brace it enough to support those areas where I feel it is most vulnerable to this.

Where can I get glass-filled putty do you guys think it would be a good idea to use this type of putty on the cardboard to smooth it and fill in small dents prior to glassing.
 

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#13 · (Edited)
ellist said:
... do you guys think it would be a good idea to use this type of putty on the cardboard to smooth it and fill in small dents prior to glassing.
As noted above, my experience with building glass bodies is limited and not particularly successful...so you can take this with the appropriate grains of salt.

My advice would be to NOT fill the the cardboard first...unless you have applied at least one coat of resin as some have suggested doing. The reason is a) I'm not sure the putty type filler will adhere to the cardboard that well and b) you'll have a difficult time sanding the putty smooth (so your next layer of glass won't have voids) without making a mess of your cardboard. Cardboard and sandpaper are just not that compatible and I've never been able to apply filler without creating some pretty ugly globs and edges that had to be sanded quite extensively.

I would be interested in what others think however.
 
#14 ·
C-boy is definately right on IMO (for what it's worth on this subject). I'd definately soak that cardboard down with resin inside and out if possible before any glass or fillers go on. Wet that board for complete saturation otherwise the adhesion of whatever you apply over it will only be as strong as the outer paper of the cardboard. This is a neat project, keep us updated. Bob
 
#15 ·
This is a real interesting project. I'd like to be able to keep up on how it progresses.

Since I am not good at glass work, and really hate it, I am not going to try to sound like I am a know it all, but want to throw out a suggestion/question.

I do think it would be better to soak the cardboard, and let it set-up. My feeling is this. If you just apply the resin to the cardboard and then apply the cloth, the cardboard could soak the resin out of the cloth. Applying a good coat to the cardboard would be like applying primer to drywall before painting. It will seal it, but give something to have the rest of the material to bite to.

Does that make sense to anyone else?

Aaron
 
#19 ·
ellist said:
I have been working on a project to build my own body using the pontiac fiero frame that is base on the lamborghini gallardo. I have built the entire body out of cardboard and MDF. Now I want to take this cardboard body and apply fiberglass to it leaving the cardboard as the substructure which I have been told is do-able, my question is how do I begin to do this is it just as simple as applying cloth and resin over these peices and letting it cure. Any help suggestion or advice would be greatly appreciated. Also can I/ or should I use fleece for this type of application.
Your an artist...really cool.
 
#21 ·
i wouldn't have wasted time with card board,although everyone is missing something.
YOU JUST SEAL IT WITH PVA GLUE
but if you go to this site you will see a photo log on just how to do it properly using card board AND urethane foam. You can buy the foam in blocks and cut it to shape or just get the two chemicals ,mix them and pour it on like this guy has.
Lithuanian sports car made from card board and foam.
 
#26 ·
i realise it's ugly( but hey,what moden car is actually attractive?) ,what I was doing by posting thqat link is pointing out is that the easiest way to make something ( anything,boat,car,swimming pool) is to use Urethane foam. The solvents in resin eat anything else, except PVA.
Millions of fiberglass projects start out as Urethane blocks,why buck the best ideas? :)
 
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