The cheapest tub pan on eBay Take 2

[JosephS]

Just starting to fill the holes with jb weld high temp paste

I never worked with this before and I am glad I am using this chassis to learn. This isn’t a pretty job so far.

It much thicker and tackier than I was expecting. It was quite difficult to work it properly into the holes. I would think that the holes here are the largest I could fill with this product.

I am trying to leave the inside without much excess so that I can just sand the bottom flat.

I think I will back the inside with tape on one hole and see if that helps keep the interior smooth and give me less finishing work.

[jwscab]

Yes definitely back the holes with something. Masking tape or cellophane or packing tape works great

[JosephS]

Yes definitely back the holes with something. Masking tape or cellophane or packing tape works great

Does the tape adhere to epoxy or will it pull off clean?

[jwscab]

Yeah it comes off reasonably. At worst you have to touch it up sanding it, but you'd have to do that anyway.

[JosephS]

I was more worried about having the tape fuse with the epoxy and creating an issue that way. I was still going to try it.

[JosephS]

I am starting to get excited about this.
It took way longer than I would have liked to knock down the jb weld. I used some 60 grit and that caused scratches on the aluminum, though that won’t be a problem.

The tape did work very well and made the inside of the chassis a bit easier to handle.

I had some carbon fiber for a t2 chassis project I got stuck on but I have been learning a lot on how to handle the material. Taping the edges is a game changer in terms of cut quality and bias direction. Just tape everything down so the pattern is right and cut though the tape. Clean edges and straight(ish) patterns

I used spray adhesive on the tub and on the back of the fabric

Start from the center leaving slack so the fiber lays lightly. Then push it slowly into all the sides and corners

The adhesive is just to make the fitting easier. I made a small mistake and just cleaned it up with acetone.

It fits great! Now all I need to do is apply the epoxy that will actually bind the carbon fiber to the tub.

After that I will do the same thing to the bottom of the tub.

[JosephS]

Placeholder

[JosephS]

I mixed up a batch of resin and applied it after dropping off the kids and before work.

A single layer of carbon fiber took a whole ounce of epoxy to wet down.

The application didn’t go flawlessly. I tried to wrap the sides as well and I didn’t let the glue dry enough so some of the glue detached from the nose while applying the epoxy. That is a lesson learned.

Once this cures I’ll drill out the holes in the tub and apply the carbon fiber to the bottom of the tub. I’m going to do 2 layers right off the batt there since the single layer is still letting the silver of the tub shine through. I was planning on at least 2 layers top and bottom to help stiffen up the chassis a bit. I am hoping for something in between a stiff cf chassis and a loose aluminum one.

[JosephS]

It looks like I accidentally made a carbon fiber tub trying to wrap my chassis. I managed to hit the internal shape of the tub perfectly, but the outersides did not adhere at all.

I tried to use a vacuum bag that I prepped for my t2 project and that was a no go. The problem I am having with the t2 tub was my vacuum bag setup. I wound up with big wrinkles on the floor of the chassis. I had to sand them down flat and cut off the outside pieces of carbon fiber. That leaves me with a very well formed internal tub.

I think I need to clean off and rough up the aluminum to make sure that the epoxy has a chance to stick. I am going to see of I can get a ceramic tile that will fit in the setup that I have. I am going to try and split the epoxy on the outside bottom layer attaching the bottom then the sides.

[JosephS]

changes for this pass
bottom worked on, not inside.
Cleaned off past attempt
fully scuffed the tub. epoxy doesn't adhere well to smooth aluminum
clamped between 2 flat surfaces, used foam to make the tail of the chassis sit down.
only the bottom surface was epoxied
sides partially wrapped

results
Under pressure epoxy filled holes
good adhesion where mechanical pressure was applied.
smooth finish.
in area of excess pressure epoxy was squeezed out leaving dry area
very flat chassis.

Notes:
previous pass of fiber didn’t adhere as well as I wanted. I started with the bottom of the chassis this time. I wrapped the sides but only but epoxy on the bottom for a first pass then sandwiched it between 2 tiles held down by hand clamps.

It was perfectly flat and well adhered. I don’t think I can take this layer off.

The chassis still flexes but when hit it makes a thud instead of ringing.

This seemed good. I had to throw a foam block under the tail to get it flat against the tile.

The defects don’t show up well on camera . The clamp pressure was excessive and caused some dry spots where the epoxy ran out.

The epoxy also wicked and pooled upwards… there were a laminated section on the top tile and not just the bottom.

Anywhere there was excess fabric it pulled away from the metal. Since only the bottom was resin coated the bunched fabric can come off with scissors.

The next step is to trim all of the excess. Fill in the voids. Then I need to sand that beautiful shine right off so I can add the finishing layer.

I am not sure if I should try an internal layer first before going to another outer layer.

[JosephS]

Update: There will be no next step. This project is over. I learned a bunch and I'm going to put my effort into a better start.

well I sure made a mess of that. I tried to use a vacuum bag pull again on the inside of the chassis.
This time the inside was coated:
Applied epoxy to the base chassis
used 2 layers
apply release film
used a breather

the results were not great but I'm learning
The vacuum was pulled too hard. this is what is creating wrinkles in my parts
far to much epoxy was used. there was a THICK layer on top that became wavy
the chassis warped- The vacuum pulls the chassis to the bag and the tail of the chassis is unsupported
the vacuum seal failed - this didn't seem to matter much honestly.

The layers were properly adhered to each other. The two layers are acting like one.
The layers are very well adhered to the metal. I can't peel this off.
the peel ply left a smooth surface, even if the bag causes waves the surface was smooth and had few wrinkles.
All the screw holes filled in- I think even a thrashed chassis can use this technique with low prep.
The tracer fibers in this cloth are not going translucent. This was 2nd quality carbon fiber but I think I need to make sure to get fiberglass tracers. I think these are kevlar.

Take Away
Use less epoxy- I should just barely be getting the parts wet
Some kind of backing needs to be used under the chassis at all times. The natural tendency is for the tail to kick up. I needs to be held down or the chassis will be reinforced in the wrong position.
peel ply should be used on all parts when a bag is used- the finish was nice.

I'm working on sanding off about an 1/16" of extra epoxy. It's think enough I started with 50 grit then went to 24 paper and I think I may need to be using a respirator instead of the N95 mask I have. The dust is a super fine and sticks to everything.

Next step-
knock down as much as I can of the high spots. file off all the rough edges. then apply epoxy to the sides of the tub. I think I'll just use a bit of black paint on any spots that show through and a bit of clear coat and call this one done. I learned a lot on this even if I was slow on the uptake. The potential for a super nice finish is still there, but It'll take more time than I want to put into this chassis right now. I think I could start a different chassis off a bit better.