LocostUSA.com

Thanks for the kind words.

I searched all over for information on how to build a custom body starting with a foan and then fiberglass, but couldn't find a good source. This series of videos meant to fill in that Gap.

Stay tuned the next episode on the fiberglass and gelcoat steps

There have been many fiberglass build ups here. Aircraft mechanics often work with composites and there are many here. I wrote a basic how to in 2008: viewtopic.php?f=36&t=3993
And then Pook went crazy!: viewtopic.php?f=36&t=8834&p=100376&hilit=foam#p100376
Airframer: viewtopic.php?f=36&t=2142&hilit=airframer&start=450
I’m leaving out a few but it is still fun to watch your tiger take shape.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

This is a link to an old style (think Big Daddy Roth) plaster and news paper form to make plug for body. Cheap and FUN to watch! Best $25 you’ll ever spend!

https://spritzbyfritz.bigcartel.com/pro ... wo-dvd-set

Thanks for the reference. I bought the CDs.

The content in these references is helpful...Thanks!

I’m sure you will like the DVD’s. I also enjoy this video. He also has ideas and demonstrates chassis build for hot rods.

https://www.tbucketplans.com/model-a-ho ... cket-mods/

I watch another with an incredible fiberglass artist. With his permission I have linked his project for your enjoyment. It raises the bar for sure! Lol

https://tbucketeer.com/threads/a-bit-mo ... ost-219578

Here is the next video, Episode #26: Fiberglass & Body Filler -> https://youtu.be/DQV-_vQU_4s


6. Fiberglass Layer
At this step, you need to decide if you are going to use the "Molded" or "Moldless" method:

• Go Moldless - This means that you plan to build a thick fiberglass shell on the foam buck and that will be your final body panel. This is a much faster way to finish the body, but the panel will probably have a significant amount of body filler in it to get a smooth surface. That body filler is heavy and likely to cause cracking and other blemishes down the road. This is a good method for a prototype or a trailer queen that won't be driven much.
• Go Molded - This means that you plan to build a mold of the final body and then use that mold to produce the final body panels. This allows you to use a much thinner temporary fiberglass shell that is only tough enough to support the body filler step. Then another 2 steps are needed to construct a female mold of the final smoothed panel and then use that mold to build the final body panels.

I chose the Molded route because in my small Tiger 700, I need to save every once of weight that I can.

I selected 2 layers of 2oz fiberglass cloth to create my shell. This is the lightest fiberglass cloth on the market. In fact its used in remote control airplane construction. I chose this light material to keep the shell thin and preserve the body contours. I used a dry layup method for the fiberglass fabric. In other words, I carefully laid out the dry fiberglass so there were no wrinkles or overlaps, and then used a light mist of 3M Super 77 spray adhesive to tack the fabric in place so it wouldn't move when the resin is applied.


I have a lot of vertical surfaces on the body, so I jacked up the side of the car I was working on, so gravity would help lay the fabric against the panels. I used polyester resin for the shell.


You will probably use multiple layers of fiberglass cloth to build your shell. Its important to plan how those layers will butt up against each other to eliminate overlaps while maximizing its strength. Areas of overlap, as well as any wrinkles in the fabric cause lumps that require extra effort to smooth out in the body filler step. In the diagram below, the "Butt and Stagger" layup will save lots of effort in the bodywork step.


7. Gelcoat Layer
The Gelcoat layer providers a protective barrier between the fiberglass laminate and the body filler. There is an intensive amount of block sanding done in the body filler step to smooth the final panel surface. Inevitably, you will sand through areas of the body filler and dig into the layer underneath. If you sand into the fiberglass cloth, it is somewhat difficult to repair the fibers and regain a smooth finish. The Gelcoat provides a sanding base layer to protect the fiberglass cloth.

To ensure good coverage, I used 2 layers of Gelcoat. This also provided a good opportunity to try some paint schemes that have rolling around in my head. I bought white gelcoat and then purchased small sample bottles of green and black polymer dye. As I applied my 2 layers of Gelcoat, I added the dye to prototype 3 different paint schemes.

Paint scheme #1 - Didn't like the front wheel well color

Paint scheme #2 - The front is better, didn't like the rear shell

Paint scheme #3 - I reversed the colors on the rear shell and Bingo! That's the paint scheme I'll use. The front gray cowl will actually be carbon fiber with a clear coat.

8. Auto Body Filler Layer
The auto body filler step is the last step, but also the most labor intensive. In reality, you will probably skim coat and sand each area 3-4 times.

• It starts with skim coating the entire body with body filler
• Then block sand it down to a somewhat smooth finish. Always sand in an "X" pattern to reduce the chance of digging groves into the panels.
• Apply black power guide coat and lightly sand the surface to identify the high and low areas on the each panel.
• Rinse and repeat 2-3 more times to achieve perfection.

I hate sanding, so I decided early on that I was going to do what ever I can to reduce my sanding effort. I started by researching sandpaper to find the best grit types, and buying high quality easy tear-off PSA rolls. I did my research on body filler as well. I found that "Evercoat Rage Ultra" billed itself as the "World's best sanding body filler". Body shops that used it, confirmed it was a high quality filler that was easy to apply and sand. I agree, this is great filler! If you want more working time when skim coating large panels, there is a variant called Evercoat Rage Ultra "Extra".


I used 80 grit sandpaper on the body filler and it seemed to be a good compromise between a smooth finish and minimizing my effort. You should finish sand with a finer grit such as 220 or 320.

Overall, I think I did a pretty good job on building straight and smooth body panels. However, I know that I'm an armature body man and I want a truly professional result. So I decided to let a local body shop finish that last 10% for me.

Here is the next video, Episode #27: Tool Roundup for building a Fiberglass Body -> https://youtu.be/0bpekNZ5rJk

The final list of tools is actually quite short and inexpensive. However, it took a considerable amount of trial and error to find the tools that work best. I'll list the tools in the order they are used in the 8 layers of the body construction. Some of these tools are used in several of the layers.

• Hack Knife - This is the one tool you need to cut foam. Its a homemade tool that starts with a hack saw blade. You cut one end at an angle to form a sharp point for plunge cuts and wrap the other end with some duct tape to create a handle. The hack Knife works great for plunge cuts, straight cuts, and intricate curvy cuts as well.
  
  Attachment:
  Hack Knife.JPG
• Orbital Sander with 36 grit sand paper disk - This is a great tool to do the initial shaping of the foam. It cuts through the foam relatively quickly, but in a very controlled manner.
  
  Attachment:
  tools orbital sander.JPG
• Shop Vacuum - The orbital sander creates a large volume of foam debris. Connecting the orbital sander to the shop vacuum collects 99% of the foam to keep your shop cleaner.
  
  Attachment:
  tools shopvac.JPG
• Sanding blocks - Sanding blocks allow you to fine tune the surface contours and flatten the panels. You will need a variety of sanding blocks to fit the many different contours of your body shape. Stiff long sanding blocks are good for large relatively flat panels, while short flexible foam sanding blocks are better suited to tight curves and intricate details. Between these two extremes, there are many variations in length and stiffness. I recommend buying a variety pack to suit the needs of your body panels. For my project I chose a stiff 16" Dura-block, a variety package of 11" Soft Sanders, and a variety package of 5" Soft Sanders.
  
  Attachment:
  durablock sanding block.jpg
• Sandpaper - Most sanding blocks are made to work with sandpaper with Pressure Sensitive Adhesive (PSA). You will be using a lot of sandpaper so buy it in large rolls. No one likes sanding and cheap sandpaper makes the job even harder. Do yourself a favor and buy a good quality sandpaper. There is very little cost difference between cheap sandpaper and good quality. I used 40 grit sandpaper to block sand the foam, plaster, and epoxy layers. I then used 80 grit for the polyester fiberglass and body filler layers. You should go to finer grits on the high build primer layer.
• Spreader - The spreader is used to apply the plaster and body filler layers. Spreaders are very inexpensive, so its good to have a variety of sizes. It may be handy to cut some spreaders into shapes that are helpful in applying filler to curved surfaces.
  
  Attachment:
  Joint compound and squeegees.JPG
• Body Filler mixing Board - You will be mixing a lot of batches of body filler, so you want a board that is easy to clean. I tried several different styles of mixing boards and found the disposable sheet type saved a lot of time. Once you are finished with a batch of body filler, you simply tear off the top disposable sheet and you are ready for the next batch. A disposable sheet mixing board comes with about 100 sheets.
  
  Attachment:
  mixing board.jpg
• Disposable kitchen containers - These containers are inexpensive easy to steal from your wife. They are great for mixing epoxy resin, polyester resin, and gelcoat because these resins don't stick to the container. Once the resin hardens, flex the container and the resin falls out. You can use a single container over and over again.
• Ribbed roller - Air bubbles tend to get trapped under the fabric when laminating fiberglass. The ribbed roller is rolled over the air bubbles slowly to release the air. Ribbed rollers are inexpensive and can be found at fiberglass suppliers.
  
  Attachment:
  Ribbed Roller.JPG
• Guide coat - Guide coat is used to find the low spots in your final panels. Guide coat is a black powder that is spread over body panels and then block sanded off. The low areas on your panel are not touched by the block sanding and remain black.
• Replicator - This is a homemade tool used to compare the left side of the body to the right to ensure they have the same contour. It is basically a tower with 3 contour gauges attached. The grid on the build table is used to precisely position the replicator in the same coordinate on both sides of the body when doing the comparison.
  
  Attachment:
  Replicator1.JPG
• Laser Level - Laser levels are used in home construction and can be found at your local home improvement store. Like the replicator, they are also useful to ensure the body is symmetrical side to side. The key features to look for in a laser level is that it is self leveling and it uses green lasers (easier to see).
  
  Attachment:
  Tools laser level1.JPG
  Attachment:
  Tools laser level2.JPG

Its been over a year since I posted an update on my project. It been year of Covid craziness and political upheaval, but the Tiger 700 made significant progress! I'll catch up this tread with a series of posts to come.

Here is where I left off...

I had a body shop put the final touches on the body buck. I think it turned out well.

Looks like you got your ‘Schmidt together. Nice job. I can appreciate the amount of work it took to get to this point.
The styling reminds me of octopus meets street rod.

I’m curious about the step in the body at what would be the door jamb line, between the front and rear clips. I’m guessing a lift up body for entry/exit but that can be done without a step using a 30-40 degree parting line or sliding the body forward an inch first to the rotating position like some fiberglass clip drag cars do where the parting line is from the production vehicle and they don’t want to split the fender.

I just remembered the headlight fairing tubes will house the taillights.

A pic next to a normal vehicle would be great to show the scale.

I found the drywall compound to be extremely slow to dry, making a long process with many steps that much longer even though it is just meant to be a thin skim coat to protect the foam from the poly resin. I’ve heard plaster of paris is much faster to cure. It would be nice to have something cheaper than poly filler that cures fast, can go on thick if needed, adheres well but doesn’t clog the paper, and can be used right out of the tub.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

Plaster of Paris cures where premixed drywall compound just dries. And it cures rapidly with an extremely short pot life. There is an in between being 20, 45 or 90 minute quick setting drywall compound that you have to add water and mix. It is, I think, a mix of both gypsum powder and Plaster of Paris in various ratios of both. even though it cures it does take a bit of time for the moisture to evaporate.

_________________
Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE

And don't forget my Cushman Truckster resto Locostusa.com/forums/viewtopic.php?f=36&t=17766

Miatav8,

The vertical step in the middle of the body serves 2 purposes.

• It breaks up the body lines, so the body doesn't seem so long and narrow
• The rear half comes off for access to the engine compartment. The front half of the body is stationary. There is a motorcycle foot peg on the right side that allows you to step up and into the cockpit.

I chose spackling compound because it shrinks less, so fewer cracks. Yes, thick layers can take a couple days to dry here in the humid Carolinas. You tend to get in a daily rhythm of applying a thin layer at the end of the day and then sand it the next morning. Plaster is worth trying. Its a bit harder and that can be a good thing.

I'll take a photo of my Tiger 700 next to regular car for perspective...Good suggestion!

BTW...I think of the exterior design as "squid" meets hot rod

Here is the next video, Episode #28: Building the Body Mold 0-> https://www.youtube.com/watch?v=UiVIrdh_mXE

Preparing the Buck
I sanded and smoothed the body to the best of my ability, but its still only 95% of the way there. I decided to let the professionals at a local body shop (Our Dreams in Mooresville NC) finish the surface. That last 5% takes a considerable amount of skill and time.

The body buck is now ready to lay a mold on top of it. That mold will be used to build the final light weight carbon fiber body panels.



I’ll start by molding the front cowl. The front cowl will be removable so I can service the electrical, brake master cylinders, steering, etc.

I masked off the edges of the cowl and added white foam core board to create a flange along the rear edge. The foam core board is attached using hot glue. You can purchase the foam core board at hobby shops and office supply stores like OfficeMax, OfficeDepot, etc.

When building a mold, be aware of any negative body contours that would lock the mold to the panel. I had 2 negative contours at the front corners that I filled with Plasteline (oil-based clay).

Then I drew an outline of how far I want the mold to extend beyond the edges of the cowl panel. I outline adds a 3” (75mm) border for the mold flange.

Then you need to prepare the surface of the plug, so the fiberglass mold does not stick to it. There are 3 typical products used to create a barrier between the plug and the mold:
• Chemical release agent – This is the thinnest coating, so it will introduce the least imperfections. The downside is that it is so thin, that it is difficult to see if you have full coverage. It also is the most expensive option.
• Poly Vinyl Alcohol (PVA) – PVA is a water-based solution that can be sprayed or brushed on the plug. It dries to a thin film that protects the plug. Once the mold is released, the PVA can be removed with water. PVA typically has a purple color to ensure full coverage.
• Mold wax – This is a thick paste wax that is applied with pad or cloth. If you want a fine finish, you can polish the wax. If so, you should apply and polish several layers of wax to ensure full coverage. Mold wax can also be applied in a thin layer and not polished. This can introduce some imperfection from the wax, but only 1 layer of wax is needed.

I chose to use both unpolished wax and PVA. This ensures there is no chance of the mold sticking to the plug. The combination of wax and PVA introduced some minor imperfections in the mold, but I knew I would be doing some sanding and bodywork anyway.

Front cowl with masking, Plasteline clay and wax applied

Front cowl with PVA applied on top


Releasing the Mold using Compressed Air
Compressed air can be used to help release the mid sections of the mold. An easy way to create air snorkels is with a ¾” (20mm) length of drinking straw that is half filled with Plasticine clay. Use the blunt end of the drill bit to press the clay into the PVA until it adheres.


Gelcoat
Polyester Gelcoat is the first layer of the mold. Gelcoat is a thick polyester resin that gives the mold a smooth surface. Gelcoat can be applied with a brush. Special care is taken around the fragile air snorkels to ensure they are not disturbed. Once the Gelcoat cures, the air snorkels are firmly affixed.

I found that 1 thick coat of Gelcoat is sufficient.

Some sources say you should apply 2 coats of Gelcoat. On larger panels, I found that the 2nd Gelcoat caused the 1st Gelcoat to wrinkle. This is because Gelcoat shrinks slightly as it cures. This is because as the 2nd coat shrinks, it grabs the 1st coat and makes it wrinkle. Since you cannot see the surface of the 1st coat, you will not know you have a wrinkled gelcoat surface until you release the mold…Yikes!


Fillet to Smooth Sharp edges
Composite fabrics like Fiberglass, carbon fiber, Kevlar, etc each have their own characteristic of “Drape”. Drape is the fabrics ability to bend and follow the contours of the mold. The thickness and the weave also effect the fabrics ability to drape.

If the plug has edges that are too sharp for the fabric you drape over, you need to fill in those edges with fillets to smooth the transition. Fillets are made with either a pre-mixed fillet compound or it can be made by mixing resin with a filler. Typical fillers include:
• Fillet blend like WEST SYSTEM 405 – This produces the smoothest finish, but is the weakest filler material.
• Cabosil (silica powder) – This produces a finish almost as smooth as 405, but adds significant strength.
• Chopped fiberglass strand - This produces a rough finish, but is the highest strength. Strictly speaking, chopped strand is not a filler because it does not absorb resin. It works best when mixed with one of the other two fillers to add strength.
Note: To ensure the resin cures properly, always mix the resin with its catalyst before adding the filler.


Lay the First layer of Fiberglass
The first layer of fabric is to support the gelcoat. So the fabric should be a lighter weight (6 OZ or less) with a tight weave and with good drape. If the fabric does not adhere to very little indentation, the Gelcoat will be weak and it will flake off. A heavy material (more than 6 OZ) can print through the Gelcoat and show its weave pattern on the mold surface.

Lay the Structural Layers of fiberglass.
After the first layer, heavy fabric can be laid in multiple layers to add strength to the mold. If weight is not a concern, chopped strand mat and polyester resin are typically used to quickly build thickness. I used 3-4 layers of chopped strand mat.

If additional strength is needed, foam, cardboard, wood, etc can be used to form ribs within the lamination.

In the photo below, you can see the mold with strengthening ribs and snorkel holes. The amber colored portions indicate a good laminate. The cloudy areas are where the lamination of the last layers is poor. This was my first panel mold and the resin cured quicker than expected on the last layer. Live and learn!


Release the mold
The mold will always stick a little to the plug. I find it helps to give the mold some “percussive love” by banging all over the mold with a rubber mallet. Then drive plastic pry wedges in all the edges to release the mold. The wedges can be purchased from a fiberglass supply store. The wedges are inexpensive. Get 10-15 wedges is varying sizes. If the edges release, but the center does not, use compressed air in the snorkels to release it.

Nice writeup. If applying gelcoat thinned for spraying, it takes multiple coats to reach enough mils. It's supposed to be thin as paper but it's has been much thicker in practice, with every gel-coated part or body I've had experience with.

If you split the mold so no curve is over 90deg, it releases ok without air and just some trimming of the gel at the seam but air would be a great way to separate with minimal effort.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12