Making a carbon fiber rc10t chassis the Competent way

[JosephS]

Great test results.

Learned a few things as well it is going to be a useful result.



The chassis was resin light. The vacuum held, but the resin from the top did not diffuse to the outside layers.


The cosmetic effect of the 3 piece wasn’t great. There were lots of orphan strands of carbon fiber.

This may be helped with more resin, maybe not.


The carbon fiber is a directional weave. I mean for the bottom to have the major weave be along the chassis and it was across.

The shape Is good geometry is good. The walls are tall enough



The corners are pretty crisp inside and out

The nose plate accidentally has the proper angle that allows for the bumper and a body to be mounted.


Very few wrinkles That may be because of the lack of resin, the breather in multiple layers reduces the problems in bagging,

[JosephS]

This is rigid and impossibly light.

Cosmetically it’s going to need a few hours of clean up but it should be just fine for my oldest who wants to make his rc10t as a model and not a running car.


I’m not sure if it’s the switch in resin, design or better technique.

I think I may trim in some cut down sides for this and add a layer of cosmetic material along the side to clean up the rough spots.

The bottom will need another coat of resin and sanding for appearances.

For the next on that is going to be a basher for a younger kid. I am going to add 1 or 2 more stiffeners and make the internal layers of fiberglass.

[JosephS]

If you must use West, it sounds like 120F for 4 to 8 hours is good. I found it in
the following newsletter from West:
http://www.westsystem.com/ewmag/18/pdf/tanks.pdf
Now, some of that epoxy is mixed slightly different, but not much.
Don't exceed 140F:
http://westsystem.com/webpages/useri...o/coldtemp.htm
(that's a clue that you may not get great thermal properties)

Link of different epoxies
https://www.aircraftspruce.com/categories/building_materials/bm/menus/cm/epoxy.html

[JosephS]

Haven't been documenting again.
Went though a few different ways to mark out chassis holes and cutouts.
I finally went by applying a layer of fiberglass to a chassis to make an external cover. I then drilled out the holes from the actual chassis. These lined up with the holes I drew on the chassis from the CAD model(I couldn't get it to print 1:1)

I started fitting in a rear bulkhead and the mounting tabs of the chassis are cut in as well as the slots for the suspension mounts. I will need to use a file and flatten out the tail by the mounting area.


If you look closely you can see that the chassis curves up in the bottom corner. When the tabs are cut out this causes a high spot at the edge.Not sure how to change this is layup.


I have a stealth mounting guide and will use that drill for the transmission.



To Finish Fitting Out

1. ☑ File Flat Rear Mounting surfaces
   
   Drill
2. ☐ Servo saver holes
3. ☑ Bulk head side supports
4. ☑ Nose tube support
5. ☑ Cut down tub sides
6. ☐ Round edges and corners
   
   Test and Fit
7. ☐ Check alignment for mounted pieces, front and rear
8. ☐ Servo saver bolt
   
   Fixing and Filling
9. ☐ redrill and misaligned holes and fill any gaps and voids
   
   Costmetic
10. ☑ apply cosmetic layer of resin to chassis bottom
11. ☐ apply cosmetic reinforcement to tub sides

[JosephS]

Applied 2 layers to the bottom the chassis.
Prep
Keyed up with 220 sandpaper
dust cleaned with isopropyl alcohol

Layup
1st layer 5.7 oz 2x2 weave adhered with 3m 77 adhesive
edges trimmed out with flush cut scissors to outline of chassis
12ml of resin mixed up and applied by brush to outside
the overall item looked 'dry'
2nd layer of 5.7 oz 2x4 weave with the long warp side running front to back.
12ml more resin applied by brush.

Notes
This stuff is fragile and pulls apart easily. next time remember to fix with 77 before cutting to stabilize the fabric.
The weave was easily disturbed causing stray strands to adhere to the material. They were quite difficult to see and remove. I stopped trimming and will trim when the resin sets.

Hopefully this adds a bit of stiffness and thickness. This will also cover up some of my drilling and cutting mistakes.

[JosephS]

Here is the chassis with the sides and bottom cleaned up. Could have used bagging to get the sides a perfect fit.

Added the sides with the carbon fiber running the long direction. I’d been making these far to dry so I coated with a layer of resin. I mixed up 24 ml and that was far more than needed for the full bottom and sides.

I sanded things down with 1000 grit to smooth things over and added a layer of 2k clear

Here is the newest attempt vs the last one.

Need to finish it up tonight. I’d been working on these way too long and I need to hand it off to my kid so he can build up his 10t.

Wondering if I should give him all titanium/aluminum hardware since he wants to shelf it.