Making a carbon fiber chassis the beginner way (part1)

[JosephS]

I learned a lot last year with my carbon fiber chassis.

I am going to start a few projects starting with a carbon fiber rpm8090 tub.

Wrappers Delight

I am starting out by using glossy automotive wrap around the chassis. The wrap will protect the original plastic from chemicals and will release from the plastics. This will also give a scratch free surface for my molds.

[JosephS]

The main way I plan on improving the results is to make better molds for the process.

I am using an orange polyester tooling coat. This will be the surface of the mold. It picks up details on the surface very well and forms a hard surface that should stand up to making a number of pieces
.

I used a special chemical release agent and applied 4 thin coats of it.

Then I mixed up the gel coat making 1.5 oz of coat using 18drop of hardener. It smells like liquid bondo.

26EB10B5-11EA-4D1B-9283-E3DB950C9B50.jpeg (14.3 KiB) Viewed 1026 times

26EB10B5-11EA-4D1B-9283-E3DB950C9B50.jpeg (14.3 KiB) Viewed 1026 times

I painted up the piece and think it’s not correct. I used a chop brush and it didn’t lay down a smooth layer. I have heard that painting technique is critical. I’ll find out.

The orange on the board is so that when I check to see if it’s dry I don’t poke at the actual work piece.


So I’m going to have to do a lot of projects fast. The unopened can has a 3 month shelf life… so I’ll have to use all of the tooling gel and I figure in about a month. It’s a big change from epoxy that I kept for a decade.

[JosephS]

Come together now let’s gel

Tooling gel coat

I got to take my first look at the orange tooling gel coat.

There was a sizable piece in the mixing cup that had cured overnight.

FA280A02-4E52-4E31-9C5E-F637EA9CA9F2.jpeg (32.65 KiB) Viewed 978 times

FA280A02-4E52-4E31-9C5E-F637EA9CA9F2.jpeg (32.65 KiB) Viewed 978 times

The gel shows extremely fine details. It copied the matte texture of the cup. I have a feeling it will reproduce details an thin as finger prints. At this thickness it looks very smooth and continuous.

AE30E4A0-2E82-48CB-9540-D405F1731F6C.jpeg (31.41 KiB) Viewed 978 times

AE30E4A0-2E82-48CB-9540-D405F1731F6C.jpeg (31.41 KiB) Viewed 978 times

The side not facing the cup looks different. It is shiny and has numerous pinholes in the finish. There were none on the mold side, but I think I will need to look out for that.

The material is pretty flexible, not at all rigid. I expect it to get more rigid as it cures longer. It’s strong for it’s thickness but I was able to tear off the piece in the photo by hand.

The problem I was having with a smooth coat may not have been the brush. The chemical have a specific do not use below 70degrees F label. When I was mixing this up it was in the high 60’s at the most. It may flow nicer at a warmer temp.

It’s also highly flammable so I can at best keep it at temp in a water bath. The amount of flame warnings is making me think I can’t use my heat gun to work out pinholes from the finish like you can with epoxy.

The smell of this stuff is strong. Even when working outside in the clear open I think I need a respirator.

[RC10th]

I would think in your profession you would have access to immense knowledge and materials for mold making ?

[JosephS]

I would think in your profession you would have access to immense knowledge and materials for mold making ?

?
Professionally I'm a scientist that works on displays(tv's),film , and digital cameras. I spend most of my time programming. This is all new to me; hence all of the notes and questions. I don't know anyone who does tooling or even engineering in this domain.

I do know the scientist who make the cherries and Cherry Garcia soft, as opposed to frozen solid. It's not relevant in anyway, but is still awesome.

[RC10th]

Maybe I'm just being ignorant but I would have thought being in the film industry you would have access to people who have professional knowledge and/or equipment in molds/models.

I do know the scientist who make the cherries and Cherry Garcia soft, as opposed to frozen solid. It's not relevant in anyway, but is still awesome.

Now that's awesome

[JosephS]

Maybe I'm just being ignorant but I would have thought being in the film industry you would have access to people who have professional knowledge and/or equipment in molds/models.

I do know the scientist who make the cherries and Cherry Garcia soft, as opposed to frozen solid. It's not relevant in anyway, but is still awesome.

Now that's awesome

The film industry has a lot of different trades. I spent time in VFX (computer generated ) the guys who make models are in SFX (physical props) and that is a rare group to run into. They have the uncanny ability to make things that look real on camera. All of that is long done when it's my turn to help people take pictures of what was made.

I'm just learning enough that I can have a reasonable conversation on carbon fiber tooling and manufacture. If I set foot in one of the facilities I would likely just stare in awe at the kind of machines and chemicals they just have access to.

On food science. At the industrial level vanilla extract is a high proof bourbon. At one point we were gifted a liter of industrial vanilla extract. It was something like 16x the strength of what is available for purchase. That was likely the most expensive bottle of liquor I had ever held. It took years before I was shown it could be drank.

[Dadio]

Are you using a vacuum chamber after mixing the gel ? I don't know much about resins but one thing I've seen a lot on YouTube is they all vacuum the resin after mixing to remove bubbles .
I'm loving watching you learn this process , good luck .

[JosephS]

Are you using a vacuum chamber after mixing the gel ? I don't know much about resins but one thing I've seen a lot on YouTube is they all vacuum the resin after mixing to remove bubbles .
I'm loving watching you learn this process , good luck .

Not all resin require vacuum degassing. I had not developed pinholes or air bubbles in any of my epoxy resin work before. I may need it for this polyester, but I'll try to work with the products as it before I add steps and equipment.

[JosephS]

Finally warm enough outside to do a second gel coat on the 8090 and a first on the rc10t4.

I see some wrinkles on the t4 gel coat and I think it’s due to the wrap underneath. I feel like the 8090 got a nice layer. Hopefully it stays warm enough that in an hour I can do another coat of gel on the t4 and a fiberglass layer on the other.

I see why it’s recommended to use a contrasting color for the gel coat. I can easily see any area missed as the black shows through the orange

[JosephS]

There is a non 0 chance that I have encased and rpm 8090 chassis and an excellent condition t4 carbon chassis in a block of polyester resin.

Once the gel coat layer is down the regular fiberglass resin can be used in lower temperatures.

The gel coat was slightly easier to apply than my first go around. I spent some time and heated up the can before I made my first application.

Supposedly you can use some acetone to thin polyester resin. I didn't do this for the inner gel coats because the tooling gelcoat contains other materials and I didn't want to risk the finish. Once the second gel coat was on the t4 I mixed the remaining gel coat with regular resin and a few drops of acetone to thin out the mixture. Hopefully this is fine because it is an intermediate layer.

Instead of using fabric I was using chopped fiberglass mat. This was easier to conform to shapes in the chassis than any fabric i have used. Once it get wetted its extremely pliable. I think I may have some air bubbles between layers. That may weaken the mold in spots when I try and use it. It also was able to wrap around the chassis edge a bit that may make it difficult to remove.

Overall this process was quicker and easier than my previous attempts.

Tomorrow will be exciting, or expensive.

[Dadio]

Fingers crossed for you

[JosephS]

Mixed results.

2 coats of release is insufficient.
The wrap adheres to the gel coat
Any gel coat wrapping edges makes removing the mold impossible without cracking the mold.

The graphite appears to adhere to the gel coat

[JosephS]

D000684A-6E11-40F5-AEFA-EECCE6F9E681.jpeg (25.35 KiB) Viewed 787 times

D000684A-6E11-40F5-AEFA-EECCE6F9E681.jpeg (25.35 KiB) Viewed 787 times

68C82079-ED00-4162-8620-2F41128E35FF.jpeg (30.25 KiB) Viewed 787 times

68C82079-ED00-4162-8620-2F41128E35FF.jpeg (30.25 KiB) Viewed 787 times

3A25DD01-BDE9-426B-AFA2-131581FB1E0A.jpeg (31.53 KiB) Viewed 787 times

3A25DD01-BDE9-426B-AFA2-131581FB1E0A.jpeg (31.53 KiB) Viewed 787 times

1A3C2C29-F0A5-4E77-9DF8-93599DAE7DCC.jpeg (19.02 KiB) Viewed 787 times

1A3C2C29-F0A5-4E77-9DF8-93599DAE7DCC.jpeg (19.02 KiB) Viewed 787 times

61004C14-49F2-4102-B5E6-0B1C5ED55FEA.jpeg (17.12 KiB) Viewed 787 times

61004C14-49F2-4102-B5E6-0B1C5ED55FEA.jpeg (17.12 KiB) Viewed 787 times

Details of the problems.

The t4 stuck was stuck to the gel coat and that is a what wrecked that mold. I had to shatter it places to get it off.

There was some obvious puckering of the wrap under that gel coat. When remolding the wrap pulled away from the chassis before it pulled from the gel coat.

There are some small bubbles in 8090 mold. Over all it looks good. Although it will need a lot of work. The corners aren’t well defined. There are some small bubbles in the surface that I can fill and with gel coat and polish up. I am most worried about the sides bring different heights.

I think I will start again on making the molds with much better flanges. And use some of the gel coat to try and fix the surface of the existing mold.

The clay I used seems to be reusable. So I can start there.

I am not sure if I want to use wrap again or just use the straight nylon chassis.

[JosephS]

Finally a good result.
I went a step easier and went for a blue gt chassis. I ran out of regular wrap and switched up to aluminum foil. I sprayed it with some contact glue and glued it to the chassis and some cardboard backer. I did 2 layers of aluminum to smooth out some wrinkle.

The final mold has some defects around the corner where the motor mounts.

I used 2 layers of fiber glass mat and vacuum bagged the piece for it to cure.

All in all this piece look like it should function. I need to polish the mold since the aluminum left lots of wrinkles but this looks completely useable.

I can actually start making chassis now.