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Learning how to build Lotus Seven replicas...together!
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PostPosted: November 21, 2006, 2:41 pm 
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Pre-reading. This is how I make automotive body parts on a professional level. This is a long process, but it is what separates the boys(speaker boxes) from the men(car bodies). This method for chetcpo is a solid body, if you want information on building it in sections, let me know, ill write the differences up for ya. Edited: The divided style is available at the bottom of the page!
Ok...lets get started.


Fiberglassing 101 Prof. Texan:

Ok we need to start with a base, a mould of what the FINAL product will look like. The mould can be made of anything, literally. But whatever is used, we need to finish it off with plaster paris--what I find the best to use. Here is the way I go about it. Cut foam to as close to the shape as possible. Then stack them together to make the primitive shape. Sand as much as possible to get it as close to the final product as possible. Then, when its as close as its gonna be(depends on what you use), you need to mix up and pour a thin layer on the foam mould. Let dry, then pour two more thin layers on. This allows each layer to dry thoroughly. Now fine sand with 180 grit until smooth and perfect. Now, ensure everything is clean(and in the immediate area) prime(2 coats) and paint(2, let them dry between sprays--any type of outside enamel paint) your creation. Kudos, we have a mould.

Ok, now we need to begin to prep and get everything ready for the plug. We need:
Fiberglass Mat( 2oz Mat)
Resin
Beeswax(although a little more expensive than regular wax, well worth it in the long run)
Gelcoat
PVA(Poly Vinyl Alcohol) (comes in paste typically, dilute it with water enough to spray, may even require heating. You can do the same with sheets!)

I like to make the plug in 7 steps:

1. Spray a heavy coat of beeswax down (Typically 3 layers).
2. Buff and shine between coats. (any imperfection will show in the final product).
3. Now, spray a light mist of PVA to cover the whole mould, let dry. It dries quick, so once its dry, spray it with a medium layer, let dry, then 2 heavy layers.(should take about 2 hours total).
4. Now, we begin to assemble the plug. Spray 3 Layers of Gelcoat, allowing each to dry between sprays.
5. Now we lay the glass. Precut small strips(I like 3”x10”strips personally) before mixin your resin(one capfull of catalyst per liter of resin).
6. Now on to the laying. The essential process of Hand-laid fiberglass is to wet the surface first and then lay your strip. Once laid down, brush a light coat of resin on top of the fiberglass while using your brush more like a blotting tool than like a paintbrush. The idea here is to completely saturate the mat while working out all the air bubbles and pockets. It’s far from easy and may take some time before you have the technique down. Remember that it is very important that this first coat be applied well to assure that the gel-coat will be firmly stuck to the fiberglass. Meanwhile, because fiberglass resin and gel-coat are flammable, only put one coat down to begin with.
7. Once you’ve finished the first layer of fiberglass, and let it cure properly, you can then put another two layers on the mould without waiting between layers. Ideally you want at least four coats.

The key to keep in mind is that it needs to be rigid, and NOT flex while the final product is curing. Once you have your plug finished, we are on to the tedious task of the actual part. Fiberglass mat is good for strength, but too much can make it brittle. Cloth is lighter, and more flexible, but takes a lot of layers to provide enough strength for a final result.

Now, trim all the excess of with a die grinder, off the edges, and tear the mould from the plug…NOT the other way around. We have no more use for the mould, we only need the undamaged plug. If there is some stickin to the mould, a little hot water should take it off. This may take several days to clean up but don’t get discouraged, you’re not that far now from having a real car body.

Now, flip the plug over and inspect it for any chips, cracks, or breaks.

Using common body filler, start filling in parts of the mold were the gel-coat has either cracked or chipped. Wherever you may think the gel-coat to be cracked or then, you can use your screwdriver to tap lightly, thus breaking the weak gel-coat and allowing for repairs. Sand down all body filler smooth and then apply body filler putty to fill in pits. Remember though this is not body filler put a putty to be worked with the filler. Once nicely sanded it’s now time to start water sanding. Using a low grit sandpaper start smoothing your mold surface. This will take a fair amount of time and patience. When the surface is smooth enough, you’ll have to spray the whole thing with two-stage primer mold. Be wary of this stuff though, body men call this stuff “Cancer in a Can!” Not only should this be sprayed in a well aired area but you should wear a double mask. The way I generally do it, is leave until the last task of the day and then run as soon as I’ve cleaned my spray gun. However, the main reason for using this is because it forms a smooth, solid, surface keeping both the gel-coat and the body-filler in place. If not, the body filler would come off when you pulled your piece, just as the mold made of drywall compound was destroyed when you originally pulled this mold.

Allowing at least 24 hours to dry, apply your first coat of Beeswax one the mold surface.

Spray the plug with PVA. 3 coats should do, allowing at least 30 minutes to dry between coats. Now you are ready to apply the first coat of gel-coat. This should be done evenly with a brush. Don’t worry so much about it being patchy in areas as you are going to apply a second coat. Once again, I like allowing at least 12 hours drying time. However, depending on where you live, you can cut this time down considerably.

After the gel-coat has dried, you are now ready for glasswork Be very contentious applying this first coat of glass because it is the most important and once a suitable amount of time to dry. However, once the first layer of fiberglass is dry you can then apply next two layers one after the other. Once the entire car has been done at least three times, you’re ready to pull the body.

Prop it up somewhere that it will not warp, it needs to completely cure/dry for 25-30 days.

If anyone sees something I missed, let me know, Ill add to it.

Hope this helps all the DIY's out there!

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Last edited by LostTexan on December 31, 2006, 10:56 pm, edited 4 times in total.

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PostPosted: November 21, 2006, 3:15 pm 
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What type and brand of resin do you suggest? Polyester or acrylic? Do I need any wax additives to remove the "tack"? (paraffin?) What type of gel-coat? Can you suggest a good place to buy this stuff?

Also, I saw where you mentioned PVA sheet but in the instructions you say to spray it on. Do you melt it in water or something? I have an endless supply of it here at work as we use PVA "bags" we use to make our carbon fiber prosthetic sockets. We always trim about half the bag off and throw it away. Any reason I shouldn't use this?

Thanks for the writeup! :D

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PostPosted: November 22, 2006, 12:43 am 
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I changed the info abou the PVA. You can use left over sheets, but you need to have a steady heat source, and lots of water. Heat the water, place sheets in until the begin to "tear". Shake, use a filter on your spray gun.

This is info from the web, I have never actually tried using sheets, but I prefer paste. And it can be bought all over the net on chemical websites.

Gelcoat wise: www.jamestowndistributors.com (white and neutral i think is the name).
Thats where I get most of my products from. Good people to work with.

Resin, i prefer Epoxy, mainly because its all Ive ever used. I think The link above also sells it. WEST System 105 Epoxy Resin.


If you cant get beeswax, use Meguiar's Mirror Glaze. You can pick it up at most hardware stores, and its cheap.

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PostPosted: November 22, 2006, 2:07 pm 
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LostTexan wrote:
I changed the info abou the PVA. You can use left over sheets, but you need to have a steady heat source, and lots of water. Heat the water, place sheets in until the begin to "tear". Shake, use a filter on your spray gun.

This is info from the web, I have never actually tried using sheets, but I prefer paste. And it can be bought all over the net on chemical websites.

Gelcoat wise: www.jamestowndistributors.com (white and neutral i think is the name).
Thats where I get most of my products from. Good people to work with.

Resin, i prefer Epoxy, mainly because its all Ive ever used. I think The link above also sells it. WEST System 105 Epoxy Resin.


If you cant get beeswax, use Meguiar's Mirror Glaze. You can pick it up at most hardware stores, and its cheap.


Whew, that stuff is $86 a gallon. :shock:

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PostPosted: November 22, 2006, 3:21 pm 
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I know, but for the application process, you arent gooing to get abetter price many other places. Like I said, this is where I get my products. I trust the company, and the outcome has been perfect every time.

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PostPosted: December 10, 2006, 12:06 am 
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Think you could post up how to do multi-piece bodies? I would like to do flanged/overlapping panels if possible. Thanks

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PostPosted: December 10, 2006, 12:22 am 
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how do you feel about fiberglass "carpet"? an ex-bodyshop buddy of mine suggested since it can be layed out and basically soaked in resin and doesn't require multiple sheets and layers. sounds like it's a bit thicker than 1/16" and is easily manipulated.

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PostPosted: December 10, 2006, 7:01 am 
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Quote:
Think you could post up how to do multi-piece bodies? I would like to do flanged/overlapping panels if possible. Thanks


Sure, Ive got to work in a little bit, but when I get home Ill start typin it up.

Gato
For a locost build, you might be able to get away with it. Since our cars arent low profile(bodu an inch or two off the ground) we really dont have to worry about speed bumps breaking or cracking it, since ive heard that the carpet can be very brittle. Ive never used the stuff, seems like the easy way around things honestly. And Ive never heard of anyone using it on a car body...just boats.

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PostPosted: December 14, 2006, 9:26 pm 
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Sorry no reply, just got my tonsils chopped out(it is worse the older you get). I am still recuperating, but once im able to stay awake for more than an hour, I will type up that second part.

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PostPosted: December 26, 2006, 1:40 am 
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Alrighty then, here I will attempt how to make seperate panels(Middy Tim). The sections in RED are what we are adding/doing differently.


NOTICE ADD ABOUT A QUARTER OF AN INCH TO THE DESIGN
For each division, plan on losing about a quarter of an inch(or thickness of separating material)

Now, on to Part II


Ok we need to start with a base, a mould of what the FINAL product will look like. The mould can be made of anything, literally. But whatever is used, we need to finish it off with plaster paris--what I find the best to use. Here is the way I go about it. Cut foam to as close to the shape as possible. Then stack them together to make the primitive shape. Sand as much as possible to get it as close to the final product as possible.
Then, when its as close as its gonna be(depends on what you use), you need to mix up and pour a thin layer on the foam mould. Let dry, then pour two more thin layers on. This allows each layer to dry thoroughly. Now fine sand with 180 grit until smooth and perfect.

Now, ensure everything is clean(and in the immediate area) prime(2 coats) and paint(2, let them dry between sprays--any type of outside enamel paint) your creation. Kudos, we have a mould.

Ok, now we need to begin to prep and get everything ready for the plug. We need:
Fiberglass Mat( 2oz Mat)
Resin
Beeswax(although a little more expensive than regular wax, well worth it in the long run)
Gelcoat
PVA(Poly Vinyl Alcohol) (comes in paste typically, dilute it with water enough to spray, may even require heating. You can do the same with sheets!)

Will need need a few more additional items.
Couple sheets of Cardboard or Hardboard(Home Depot, depends on how many sections you want)
Nuts and Bolts(for this write up we will need about 5)
Fiberglass Cloth(any light weight is fine, just make sure it will tear and fit into the corners good)


I like to make the plug in 7 steps:

Heres where the Hardboard comes into play. Now take the cardboard and cut it to fit the curve of the body section where you want it to end(protruding from the mould about 3 inches), and the next begin. If you are good with glue, go for it, I prefer tape to hold it down. This will be the section division.

Also, we can only make one section at a time, because when we tape the Hardboard, we want the tape on the side NOT being made…tape will make things look, well, off.

Here is where we tear the cloth into tiny pieces, to get in the corners where the body meets the hardboard. Also, everything must include (waxing, PVA, gel, and FG) up to the top of the hardboard.


1. Spray a heavy coat of beeswax down (Typically 3 layers).
2. Buff and shine between coats. (any imperfection will show in the final product).
3. Now, spray a light mist of PVA to cover the whole mould, let dry. It dries quick, so once its dry, spray it with a medium layer, let dry, then 2 heavy layers.(should take about 2 hours total).
4. Now, we begin to assemble the plug. Spray 3 Layers of Gelcoat, allowing each to dry between sprays.
5. Now we lay the glass. Precut small strips(I like 3”x10”strips personally) before mixin your resin(one capfull of catalyst per liter of resin).
6. Now on to the laying. The essential process of Hand-laid fiberglass is to wet the surface first and then lay your strip. Once laid down, brush a light coat of resin on top of the fiberglass while using your brush more like a blotting tool than like a paintbrush. The idea here is to completely saturate the mat while working out all the air bubbles and pockets. It’s far from easy and may take some time before you have the technique down. Remember that it is very important that this first coat be applied well to assure that the gel-coat will be firmly stuck to the fiberglass. Meanwhile, because fiberglass resin and gel-coat are flammable, only put one coat down to begin with.
7. Once you’ve finished the first layer of fiberglass, and let it cure properly, you can then put another two layers on the mould without waiting between layers. Ideally you want at least four coats.


The key to keep in mind is that it needs to be rigid, and NOT flex while the final product is curing. Once you have your plug finished, we are on to the tedious task of the actual part. Fiberglass mat is good for strength, but too much can make it brittle. Cloth is lighter, and more flexible, but takes a lot of layers to provide enough strength for a final result.

Now, trim all the excess of with a die grinder, off the edges, and tear the mould from the plug…NOT the other way around. We have no more use for the mould, we only need the undamaged plug. If there is some stickin to the mould, a little hot water should take it off. This may take several days to clean up but don’t get discouraged, you’re not that far now from having a real car body. We do not want to break any of the mould on the side not being made. So pretty much ignore the ripping out process.

Now, flip the plug over and inspect it for any chips, cracks, or breaks.

Using common body filler, start filling in parts of the mold were the gel-coat has either cracked or chipped. Wherever you may think the gel-coat to be cracked or then, you can use your screwdriver to tap lightly, thus breaking the weak gel-coat and allowing for repairs. Sand down all body filler smooth and then apply body filler putty to fill in pits. Remember though this is not body filler put a putty to be worked with the filler. Once nicely sanded it’s now time to start water sanding. Using a low grit sandpaper start smoothing your mold surface. This will take a fair amount of time and patience. When the surface is smooth enough, you’ll have to spray the whole thing with two-stage primer mold. Be wary of this stuff though, body men call this stuff “Cancer in a Can!” Not only should this be sprayed in a well aired area but you should wear a double mask. The way I generally do it, is leave until the last task of the day and then run as soon as I’ve cleaned my spray gun. However, the main reason for using this is because it forms a smooth, solid, surface keeping both the gel-coat and the body-filler in place. If not, the body filler would come off when you pulled your piece, just as the mold made of drywall compound was destroyed when you originally pulled this mold.

Now, we want to repeat the whole process for the next section(if you only have 2 sections, this will be your last).


With both sections complete tape the lips on both sections with masking tape(we are gonna drill and we don’t want cracks), place a piece of hardboard between the 2 sections( long enough to create about a inch and a half lip on the other side), clamp the sections together, and drill 3 holes, when the holes are drilled, bolt them and tighten them down good(not too much or this can crack the FG as well).

Image

Here is what the sections should look like(MINUS THE SEPERATOR!). The bolt holes will serve 2 purposes: they will keep the sections straight, and ensure when we drill the next set of holes, they will line up perfectly.



Allowing at least 24 hours to dry, apply your first coat of Beeswax on the inside of mold surface.

Spray the plug with PVA. 3 coats should do, allowing at least 30 minutes to dry between coats. Now you are ready to apply the first coat of gel-coat. This should be done evenly with a brush. Don’t worry so much about it being patchy in areas as you are going to apply a second coat. Once again, I like allowing at least 12 hours drying time. However, depending on where you live, you can cut this time down considerably.

After the gel-coat has dried, you are now ready for glasswork Be very contentious applying this first coat of glass because it is the most important and once a suitable amount of time to dry. However, once the first layer of fiberglass is dry you can then apply next two layers one after the other. Once the entire car has been done at least three times, you’re ready to pull the body panels.

Now, once we have it all nice and dry, tape of each side of the new lip, we need to drill more holes before we unbolt the old bolts. Drill the holes(I like about 6 bolts for a nose to mid section connection). And unbolt the old bolts, discard the hardboard or cardboard, and find a nice rubber trim piece(not required, just suggested) to run the length of where the sections join.

Prop it up somewhere that it will not warp, it needs to completely cure/dry for 25-30 days.

Im sure this will probably not be detail enough, so any detailed questions WILL be answered.


Just Ask.

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Last edited by LostTexan on December 26, 2006, 1:45 am, edited 1 time in total.

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PostPosted: December 26, 2006, 1:45 am 
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Wow. Thanks so much for writing this up for us. You are truely an asset to this community.

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Last edited by chetcpo on December 26, 2006, 1:48 am, edited 1 time in total.

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PostPosted: December 26, 2006, 1:46 am 
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I try to contribute what I do know, so when I get stuck on something I don't know...I can ask freely.


...Because I will have lots of questions! :lol:

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PostPosted: March 5, 2007, 8:03 am 
The other other book - How to Build Your Own Tiger Avon Sports Car for Road or Track, has a great section on this stuff as well. Probably the best part of the book in my opinion. The example they show is for a single seater, but has a lot of good detail shots and making flanges etc for multiple sections.

Eric
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PostPosted: March 8, 2007, 5:23 pm 
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Keep in mind that the cost of West System epoxy needs to include the hardener as well. It is mixed in roughly a 3.5:1 ratio. Note that the "gallon" of resin is .98 gallons actually and a "quart" size hardener is something like .86 quart actually. This keeps the ratio so you run out of both at the same time. You also need a pump kit for about $12.

I did my fenders and one-piece hood nose all with West System. Yes, expensive. Between the fenders, nose/hood and bucks, we went through four or five (I lost count) "gallon" kits. Very easy to work with though. Just pump the resin into a cup, use the same number of pumps on the hardener and mix. The pumps are sized to give the correct ratio with each stroke.

I have not tried the less expensive resins, so I don't have anything to compare against. I am within driving distance of Aircraft Spruce, so I picked up all my resin and fiberglass from them. Prices seem similar to the outfit mentioned above.

John


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PostPosted: March 8, 2007, 5:26 pm 
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I was also going to mention that these pages from George Cushing have a lot of good nose design information:

http://www.georgecushing.net/QandD.html
http://www.georgecushing.net/Nosecone2.html

John


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