How to make a carbon fiber bicycle fork
Step 1: Materials
- carbon fiber mat
- 404 High density adhesive filler
- vacuum bag materials
- Trash bags
Step 2: Tools
- CNC router
- vacuum pump
- ban saw
- drill press
- drill bits
- tap and die set
- drill bits
Step 3: Choose Your Setup
Before you start to design your fork you will need to get your hub, rim, decide on what type of brake you want, and the size of your head tube. The fork I made is going to be for a front wheel drive bicycle so I went with a NuVinci hub, 20" wheel, disk brake, and 1 1/8 headset.
Step 4: Design and Cut Out the Wheel Mounts
the wheel mounts need to be strong enough to hold the wheel to the fork during high speed braking. The mounts I will use three bolts for mounting. The left mount has a disk brake attachment and the right mount has an attachment for a chain tensioner.
Step 5: Fork Jig
When assembling the fork you will need the help of a jig to get the wheel mounts in the correct places. When building the jig you will need MDF threaded rod, nuts and washers. Place a fork on a flat table with the steering tube level with the table. measure the distance form the steering tube to the wheel mounts, the distance from the table to the wheel mounts and the diameter of the steering tube. In drawing software plot all the points to establish the mounting locations. The software I used is Autodesk Inventor. Once the three points are in the software then you can design your jig around them.
Step 6: Design the Fork
using the same points as the jig design the fork.
Step 7: Design the Female Molds
You will need a top and bottom female mold that splits in the center of your fork.
Step 8: Cut Out the Molds on the CNC
Step 9: Epoxy Sand and Wax the Molds
Step 10: Vacuum Bag the Carbon Fiber
- lay down a trash bag
- place mastic tape around your mold.
- cut out the vacuum bag materials.
- wet out your mold with epoxy
- wet out your carbon fiber with epoxy
- lay in two layers of wet carbon fiber
- vacuum bag the mold overnight
Step 11: Remove the Part From the Mold and Trim the Edges
- to trim the edges use a band saw and sand paper.
Step 12: Fill With Thickened Epoxy
- I wanted to make sure this part was very strong so I filled most of the fork with thickened epoxy.
- now is the time to glue in the steering tube to one half of the fork
- wax another pipe and glue it to the other half
- once dry pop off the waxed pipe and it will leave space for when you glue the two sides together.
- once dry sand the thickened epoxy
Step 13: Glue Both Sides Together
- use electrical tape to hold both sides together while they dry.
- after your fork is dry sand it smooth.
Step 14: Drill Holes for Your Wheel Mounts
- pick out the bolts you want to use find the tap and drill bit that goes with it
- place the fork in your jig
- clamp your wheel mounts to the outside of the fork
- drill the bolt holes
- don't tap the holes yet
Step 15: Wrap the Perimeter in Carbon Fiber
- wet out the carbon fiber
- wrap the perimeter with a strip of carbon fiber
- vacuum bag the fork
- once dry use a dremel and open the holes on the inside of the fork don't drill all the way through
- tap the holes
Step 16: Make It Shiny
- place electrical tape over the holes
- hang the fork and brush on epoxy to get a nice shine
assemble your fork and bolt it on to your wheel.